*This text was prepared by Kanishka Seneveirathna, Natalie LaForest, and Boyd Mori from the University of Alberta
Under the supervision of Dr. Boyd Mori at the University of Alberta, the ecological and agricultural entomology lab employs diverse molecular methods to tackle pest-related problems and develop integrated pest management approaches. Here we highlight research conducted by two graduate students: Kanishka Seneveirathna and Natalie LaForest.
Kanishka’s research uses population genetics to detect and monitor invasive insects in the prairie ecosystem. His research focuses on reconstructing the invasion routes of wheat midge (Sitodiplosis mosellana) and diamondback moth (Plutella xylostella), two devastating pests, by determining their origins in North America. To understand their invasion patterns, Kanishka employs a genomic approach (RADSeq), which allows for genome-wide population structure analysis.
A pheromone trap (left) used to collect adult wheat midge for population genetic analyses. The adult midge are trapped on a sticky card (right). Pictures by Kanishka Seneveirathna, University of Alberta.
By reconstructing the invasion routes of these pests, Kanishka aims to identify their origins and determine the genetic diversity and structure of different populations. This comprehensive understanding will facilitate the development of integrated pest management strategies, including forecasting systems and insecticide resistance management strategies. Initial findings indicate multiple independent invasion events for wheat midge across North America.
Moving forward, Kanishka and the Mori Lab team will work with members of the PPMN to collect a larger number of samples across the Prairies, ensuring comprehensive coverage. Collaboration with international research groups is also on the agenda, enabling the validation of findings and broader knowledge exchange. The goal is to develop effective management strategies to mitigate the damage caused by these invasive pests and enhance the productivity and quality of canola and wheat crops in the Canadian Prairies.
Pheromone traps (A) are used to collect adult diamondback moths in canola fields. Once trapped, the moths are removed from the sticky cards that are placed on the floor of the pheromone trap (B). To collect diamondback moth larvae for population genetic analyses, canola is sampled using sweep nets (C).Pictures by Kanishka Seneveirathna, University of Alberta.
Natalie’s research focuses on integrated pest management, more specifically the ecosystem service of weed seed predation performed by ground beetles (Coleoptera: Carabidae). Previous research on determining the species of weeds consumed by this group of beneficial insects have used seed cards in the field or cafeteria choice tests in the laboratory. Natalie’s work uses a multiplex-PCR approach, where she uses the DNA found within the gut of field captured ground beetles to determine what the ground beetles are consuming in the field. She is designing species-specific primers of agronomic significant weeds to decipher this significant predator-prey interaction.
Throughout the 2021 and 2022 seasons, the most abundant ground beetle species collected has been Pterostichus melanarius, which is an introduced, opportunist generalist predator. Natalie is focusing on ground beetles in wheat and industrial hemp, but there are other members in the Mori lab looking at the prey items of ground beetles in canola and pulses. Identifying species specific predator-prey interactions will development more sustainable pest management strategies for producers.
A pitfall trap full of adult ground beetles (Coleoptera: Carabidae); pitfall traps are used to collect ground beetles and other insects during the growing season. Picture by Natalie LaForest, University of Alberta.
Wheat midge (Sitodiplosis mosellana) emergence is reduced when soil moisture is insufficient to terminate spring diapause. Dry conditions in southcentral Manitoba as well as central and southern regions of Alberta have likely resulted in reduced emergence of larvae from the soil.
In regions where rainfall was sufficient to trigger the end of wheat midge diapause and the completeion of wheat midge development, we expect that eggs and larvae should be the most abundant life stages (Figs. 1 and 2).
Figure 1. Proportion (%) of the wheat midge (Sitodiplosis mosellana) population that is predicted to be in the egg stage in western Canada, as of July 16, 2023.Figure 2. Proportion (%) of the wheat midge (Sitodiplosis mosellana) population that is predicted to be in the larval stage in western Canada, as of July 16, 2023.
Simulated development at Regina, Saskatchewan and Grande Prairie, Alberta indicates that adult emergence has peaked (Fig. 3). Development in the Peace River region is approximately 1 week behind development of wheat midge in eastern Saskatchewan.
Figure 3. Predicted development of wheat midge (Sitodiplosis mosellana) near Regina, Saskatchewan and in the Peace River region as of July 16, 2023. Note, Sm L1-2 in the legend refers to wheat midge larvae that are feeding in wheat heads. The model used to simulate wheat midge development was developed by Olfert et al. (figure by Ross Weiss, 2023).
It may still be important to be scouting for adult wheat midge in some areas of the prairies. For more information about scouting and economic thresholds for wheat midge, check out the wheat midge monitoring protocol and the Insect of the Week for Week 8, that featured wheat midge. More information is available from Alberta Agriculture and Irrigation, the Saskatchewan Ministry of Agriculture, and Field Crop and Forage Pests and their Natural Enemies in Western Canada available for free download from our Field Guides page.
Wheat midge (Sitodiplosis mosellana) emergence is limited when soil moisture is lacking. Dry conditions in southcentral Manitoba as well as central and southern regions of Alberta have likely resulted in reduced emergence of larvae from the soil. The wheat midge development model indicates that peak emergence of adults is now occurring. Oviposition is predicted to have begun across most of the prairies and eggs should be the most abundant lifestage (Fig. 1).
Figure 1. Percent of the wheat midge (Sitodiplosis mosellana) population that is predicted to be in the egg stage in western Canada, as of July 9, 2023. Note that wheat midge may not be active in all parts of the prairies, for example in regions where populations were absent last year or in regions where it did not rain in May and June.
In fields across Saskatchewan and western Manitoba, if wheat midge are present, model simulations indicate that egg development is progressing and larvae should be present (Fig. 2).
Figure 2. Percent of the wheat midge (Sitodiplosis mosellana) population that is predicted to be in the larval stage (in wheat heads) in western Canada, as of July 9, 2023.
The wheat midge model, run for Regina, Saskatchewan indicates that adult emergence has peaked (Fig. 3) in that area. Oviposition should peak later this week. Larval populations (in wheat heads) should reach peak populations later next week.
Figure 3. Predicted development of wheat midge (Sitodiplosis mosellana) near Regina, Saskatchewan as of July 9, 2023.
Based on the occurrence of wheat midge adults, field monitoring should begin now, if it has not started already. In order to assess wheat midge populations and to take the appropriate action for management, it is recommended that fields should be monitored when wheat is between heading and flowering. Field inspection should be carried out after 8:30 p.m. when the female midge are most active. Females are more active when the temperature is above 15°C and wind speed is less than 10 km/h. Wheat midge populations can be estimated by counting the number of adults present on four or five wheat heads.
Macroglenes penetrans is a beneficial parasitoid wasp from the family Pteromalidae. It is an important natural enemy of wheat midge. This small, black wasp can be seen emerging in large numbers from wheat stubble shortly after wheat midge adults are first sighted. This means that often they are emerging into canola fields and then have to disperse to find wheat fields where their hosts are active. Macroglenes penetrans is a parasitoid that lives inside the wheat midge larva and overwinters within the wheat midge larval cocoon. In the spring, the parasitoid larva develops to emerge from the wheat midge cocoon buried in the soil and then the adult parasitoid seeks out wheat midge eggs.
A very small adult Macroglenes penetrans on a wheat head. Picture credit: Shelby Dufton, AAFC Beaverlodge Research Farm.
Macroglenes penetrans is an important part of wheat midge management – parasitism rates can reach upwards of 70% of the wheat midge population! The numbers of this parasitoid overwintering inside wheat midge cocoons are counted during the fall soil core survey, so that the survey map only includes counts of non-parasitized wheat midge.
Wheat midge (Sitodiplosis mosellana) development is ahead of normal in 2023. Last week, wheat midge pupae were just beginning to appear at the soil surface. This week, where wheat midge populations are present, pupae should be the most abundant lifestage (Fig. 1).
Figure 1. Proportion (%) of the wheat midge (Sitodiplosis mosellana) population that is expected to be in the pupal stage in western Canada, as of July 2, 2023.
First emergence of adults was reported last week and the model indicates that peak emergence has not yet occurred. Model simulations indicate that eggs and larvae should be occurring in fields across Saskatchewan and western Manitoba (Fig. 2).
Figure 2. Proportion (%) of the wheat midge (Sitodiplosis mosellana) population that is expected to be in the egg stage in western Canada, as of July 2, 2023.
Based on the occurrence of wheat midge adults, field monitoring should begin now, if it has not started already. In order to assess wheat midge populations and to take the appropriate action for management, it is recommended that fields should be monitored when wheat is between heading and flowering. Field inspection should be carried out after 8:30 p.m. when the female midge are most active. Females are more active when the temperature is above 15°C and wind speed is less than 10 km/h. Wheat midge populations can be estimated by counting the number of adults present on four or five wheat heads.
Wheat midge (Sitodiplosis mosellana) development is ahead of normal. Last week, wheat midge pupae were just beginning to appear at the soil surface. This week, where wheat midge populations are present, pupae should be the most abundant life-stage (Fig. 1). Recent rainfall in the Peace River region and Edmonton regions may have resulted movement of larvae to the soil surface and subsequent occurrence of pupae. First emergence of adults was reported last week.
Figure 1. Percent of wheat midge (Sitodiplosis mosellana) that is predicted to be in the pupal stage in western Canada, as of June 25, 2023.
Model simulations indicate that adults may be occurring in fields near Saskatoon, Regina, Estevan and Melita (Fig. 2). It is expected that adult populations may peak later next week. Oviposition is predicted to begin over the next few days.
Figure 2. Percent of wheat midge (Sitodiplosis mosellana) that is predicted to be in the adult stage in western Canada, as of June 25, 2023.
Based on the occurrence of wheat midge adults, field monitoring should begin now. In order to assess wheat midge populations and to take the appropriate action, it is recommended that fields should be monitored when wheat is between heading and flowering. Field inspection should be carried out after 8:30 p.m. when the female midge are most active. Females are more active when the temperature is above 15°C and wind speed is less than 10 km/h. Wheat midge populations can be estimated by counting the number of adults present on four or five wheat heads.
Now is the time to get out and scout for wheat midge!
Wheat midge are small, orange, fragile-looking flies that attack members of the grass family including barley, couch grass, wheat grass, triticale, and spring rye, though their preferred host is wheat.
Adult wheat midge. Picture credit: Shelby Dufton and Amanda Jorgensen, both of AAFC-Beaverlodge.
Adults emerge from mid-June through mid-July and typically coincide with wheat head development and flowering. Wheat midge remain in the humid crop canopy throughout the day and emerge on calm, warm evenings to mate and lay eggs. Eggs are laid singly or in groups of three to five on wheat kernels prior to flowering.
Adult wheat midge. Picture credit: Shelby Dufton and Amanda Jorgensen, both of AAFC-Beaverlodge.
Upon hatching, larvae crawl to developing kernels and feed for two to three weeks. Larval feeding damage results in shriveled, misshapen, cracked, or distorted kernels. Kernels must be inspected within the glume, as damage may not be readily apparent at a glance. Lost or damaged kernels from feeding result in lower crop yield and quality. The Canadian Grain Commission allows midge damage between two and five percent prior to impacting the assigned grade.
Wheat midge larva on a damaged wheat kernel. Picture credit: Amanda Jorgensen, AAFC-Beaverlodge.
After feeding, larvae remain inside the heads until rain or a moisture event occurs, at which point they drop to the soil, bury themselves, and form a cocoon to overwinter. In the spring, if moisture and temperature requirements are met, larvae leave their cocoons and return to the soil surface, pupating for a period of two weeks.
Wheat fields should be inspected for wheat midge in late June and early July, as wheat heads emerge, and females are laying eggs on the developing heads. Scouting should occur in the evening (after 8:30 PM) on calm, warm (15 ˚C) evenings. The number of adults should be counted on four to five wheat heads in three or four locations. Insecticide applications should be considered if economic thresholds are met. To maintain optimum grain grade, the economic threshold is one adult wheat midge per eight to ten heads during susceptible stages (wheat head emergence up until flowering). To prevent yield loss, the economic threshold is one adult wheat midge per four to five heads.
Varieties of midge tolerant wheat are available to help manage this pest! More information on these can be found at www.midgetolerantwheat.ca.
Are there any natural enemies that stand up to wheat midge? Yes! The parasitoids will be featured in an upcoming issue of Insect of the Week.
Wheat midge (Sitodiplosis mosellana) overwinter as larval cocoons in the soil. Soil moisture conditions in May and June largely determine whether or not larvae exit cocoons to move to the soil surface to continue development (i.e., to pupate then emerge as adults this season). Adequate rainfall promotes termination of diapause and movement of larvae to the soil surface where pupation occurs. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Wheat midge emergence may be delayed or erratic if rainfall does not exceed 20-30 mm during May and June.
Cumulative rainfall from May 1-June 18, 2023 across western Manitoba, most of Saskatchewan, and northwestern Alberta now exceeds the threshold (30 mm) required to terminate larval diapause. Though late, the rainfall event last week in the Edmonton region of Alberta may promote movement of larvae to the soil surface.
The wheat midge model indicates that, where wheat midge populations are present, larvae have begun to move to the soil surface (Fig. 1).
Figure 1. Proportion (%) of the larval population of wheat midge (Sitodiplosis mosellana) that is expected to have moved to the soil surface across western Canada, as of June 18, 2023.
Pupae are expected to be in the soil in the Peace River region, localized areas of Saskatchewan, and southwestern Manitoba (Fig. 2).
Figure 2. Proportion (%) of the wheat midge (Sitodiplosis mosellana) population that is predicted to be in the pupal stage in western Canada, as of June 18, 2023.
Model output suggests that first adults may be appearing in fields in southeastern Saskatchewan and southwestern Manitoba this week. Dr. Tyler Wist reports that adult wheat midge have been found on sticky cards baited with pheromone lures, including at the AAFC research farm in Saskatoon.
Scouting for adult wheat midge should start now. Over the next few weeks, the Prairie Pest Monitoring Network will continue to use phenology models to predict the status of wheat midge development and will provide additional updates.
Wheat midge (Sitodiplosis mosellana) overwinter as larval cocoons in the soil. Adequate rainfall in May and June is a signal to larval cocoons to end their diapause and move to the soil surface to pupate. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Wheat midge emergence may be delayed or erratic if rainfall does not exceed 20-30 mm during May. The Olfert et al. (2020) model indicated that dry conditions may result in delayed adult emergence, delayed oviposition by female wheat midge, fewer adults, and fewer eggs laid.
In the last few weeks, rainfall events over parts of the prairies may have provided the cue to end wheat midge larval diapause. Cumulative rainfall from May 1 to June 11 across western Manitoba, most of Saskatchewan and northwestern Alberta now exceeds the threshold of 30 mm of rain required to terminate the larval diapause of wheat midge (Fig. 1).
Figure 1. Areas in western Canada where cumulative rainfall from May 1 to June 11, 2023 is equal to or greater than 30 mm, which is the threshold required to promote movement of wheat midge (Sitodiplosis mosellana) larvae to the soil surface where they will pupate.
The wheat midge model indicates that, where wheat midge populations are present, larvae have begun to move to the soil surface in some areas of the prairies (Fig. 2).
Figure 2. Percent of the wheat midge larval population (Sitodiplosis mosellana) that has moved to the soil surface across western Canada, as of June 11, 2023.
In contrast to the wet areas on the prairies, wheat midge adult emergence might be delayed in 2023 in areas that have not yet received much rain. It is also possible that the wheat midge larval cocoons will remain in a diapause state in the dry areas of the prairies until a future year when spring moisture is more suitable for wheat midge development.
Scouting for adult wheat midge usually starts in late June or early July. Over the next few weeks, the Prairie Pest Monitoring Network will continue to use phenology models to predict that status of wheat midge development and provide additional updates.
Insect scouting and monitoring season is getting into full swing!
Weather patterns in May and so far in June have been perfect for the development of some insect pests, but suboptimal for others. However, it is hard to generalize, as some parts of the prairies have been wet and others dry. Similarly, some areas have been very warm, while others have been cooler. This year it will be very important to scout and to monitor insect populations at the field-scale.
Grasshoppers thrive in warm, dry conditions. This week, some 4th instar nymphs were spotted in ditches in southwestern Saskatchewan, although there are many first, second and some third instar nymphs as well. Signs of damage are starting to appear. Overall grasshopper development continues to be ahead of schedule and two-striped grasshoppers continue to be prevalent.
Diamondback moths that arrived in early May have likely reproduced and adult moths found now could be from the first generation produced on the prairies. Diamondback moths develop rapidly when it is warm and their population densities can build up quickly with each generation. Be ready to scout if pheromone traps in your area have detected diamondback moths this spring.
Bertha armyworm development is also well ahead of schedule – pupal development could be 90% complete in some areas and adult moths could already be flying around. Watch the provincial websites in Alberta, Saskatchewan, and Manitoba for reports on bertha armyworm pheromone trap captures for your area over the next few weeks.
This week, the Insect of the Week featured ground beetles and rove beetles! Both can prey on different life stages of the pea leaf weevil and on other insect pests (and slugs!).
Please read this week’s posts in the Weekly Update for more information about the insects listed above and for a sneak peak of wheat midge development!
Remember, insect Monitoring Protocols containing helpful insect pest biology, how and when to plan for in-field scouting, and economic thresholds to help support in-field management decisions. All are available to read or download for free!
Questions or problems accessing the contents of this Weekly Update? Please contact Dr. Meghan Vankosky (meghan.vankosky@agr.gc.ca) to get connected to our information. Past Weekly Updates, full of information and helpful links, can be accessed on our Weekly Update page.
Wheat midge (Sitodiplosis mosellana) overwinter as larval cocoons in the soil. Adequate rainfall in May and June is a signal to larval cocoons to end their diapause and move to the soil surface to pupate. where pupation occurs. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Wheat midge emergence may be delayed or erratic if rainfall does not exceed 20-30 mm during May. The Olfert et al. (2020) model indicated that dry conditions may result in: a. Delayed adult emergence and oviposition b. Reduced numbers of adults and eggs
Figure 1. Areas in western Canada where cumulative rainfall (mm) from May 1 to June 4, 2023 is sufficient (greater than 30 mm) to promote movement of wheat midge (Sitodiplosis mosellana) larvae to the soil surface.
In the last few weeks, rainfall events over parts of the prairies may have provided the cue to end wheat midge larval diapause. From May 1 to June 4, cumulative rainfall was normal or above normal in the Peace River region and parts of Saskatchewan (Fig. 1). Larvae, if present, are likely moving towards the soil surface in the Peace River region and in wet areas of Saskatchewan (Fig. 2).
Figure 2. The proportion of the wheat midge (Sitodiplosis mosellana) larval population that has moved to the soil surface across western Canada, as of June 4, 2023.
In contrast to the wet areas on the prairies, wheat midge adult emergence might be delayed in dry areas 2023. It is also possible that the wheat midge larval cocoons will remain in a diapause state until a future year when spring moisture is more suitable for wheat midge development.
Scouting for adult wheat midge usually starts in late June or early July. Over the next few weeks, the Prairie Pest Monitoring Network will continue to use phenology models to predict that status of wheat midge development and provide additional updates.
The Field Heroes campaign continues to raise awareness of the role of beneficial insects in western Canadian crops. Check the recently updated Field Heroes website for scouting guides, downloadable posters, and videos. Learn about these important organisms at work in your fields!
Two NEW Field Heroes resources for 2021 include:
The NEW Pests and Predators Field Guideis filled with helpful images for quick insect identification and plenty of tips to manage the pests AND natural enemies in your fields. Claim your free copy at http://fieldheroes.ca/fieldguide/ or download for free to arm your in-field scouting efforts!
Cool, wetter growing seasons generally favour wheat midge development. Wheat midge larvae overwinter in the soil in larval cocoons. Adequate soil moisture (May-June) is required to terminate diapause, resulting in movement of larvae to the soil surface. The wheat midge model was run to determine potential numbers of overwintering wheat midge larvae.
During May and June weather conditions were cooler and wetter than normal across most of Alberta. These model runs indicated that weather conditions that would promote diapause termination and movement of larvae to the soil surface were favourable, and may have resulted in higher than average adult populations in early July. Conversely, warm, dry conditions occurred across most of Manitoba and were not suitable for larval development during May and June. Figure 1 represents the potential number of larval cocoons (as of August 17, 2020). Densities of wheat midge larval cocoons were predicted to be greater across Alberta than Saskatchewan and Manitoba (Fig. 1). Figure 2 provides a comparison of densities for the same time period in 2019. Low densities in 2019 were attributed to well below normal precipitation during the period of April to June (Fig. 2).
Figure 1. Predicted number of larval cocoons of wheat midge (Sitodiplosis mosellana) across the Canadian prairies as of August 17, 2020.Figure 2. Predicted number of larval cocoons of wheat midge (Sitodiplosis mosellana) across the Canadian prairies as of August 17, 2019.
Review information supporting in-field monitoring for wheat midge (Fig. 3) and its parasitoid, Macroglenes penetrans (Fig. 4), posted back on Week 14 of the 2020 growing season.
Figure 3. Wheat midge (Sitodiplosis mosellana) laying their eggs on the wheat heads (Photo: AAFC-Beaverlodge-S. Dufton & A. Jorgensen).Figure 4. Macroglenes penetrans, a parasitoid wasp that attacks wheat midge, measures only ~2 mm long. (Photo: AAFC-Beaverlodge-S. Dufton).
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Click to link to last week’s information posted for Wk 13 (released 23Jul2020) to review the predictive model outputs for this insect pest.
Monitoring:When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15 ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (Fig. 1). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
Figure 1. Wheat midge (Sitodiplosis mosellana) laying their eggs on the wheat heads (Photo: AAFC-Beav-S. Dufton & A. Jorgensen).
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (Fig. 2), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Figure 2. Macroglenes penetrans, a parasitoid wasp that attacks wheat midge, measures only ~2 mm long. (Photo: AAFC-Beav-S. Dufton).
Economic Thresholds for Wheat Midge:
a) To maintain optimum grade:1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) For yield only:1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
Wheat midge and its doppelganger, the lauxanid fly, were featured as the Insect of the Week in 2019 (for Wk11). Review that post for descriptions and photos to help with in-field scouting for this economic pest of wheat! Additionally, the differences between midges and parasitoid wasps were featured as the current Insect of the Week in 2019 (for Wk12). Not all flying insects are mosquitoes nor are they pests – many are important parasitoid wasps that actually regulate insect pest species in our field crops.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
This week (as of July 19, 2020), regions of the Canadian prairies are either at a sensitive time for wheat midge monitoring OR the opportunity to scout and apply insecticides to prevent adult midge from laying eggs may have passed. Scouting remains essential now, especially in areas where wheat midge development was slightly delayed according to last week’s model output (Table 1). Note that the model predicted populations near Lethbridge, Grande Prairie and Lacombe would be at 90% emergence on July 23, July 25, and July 26, respectively.
This week, wheat midge model runs indicate that, where wheat midge are present and rainfall has been adequate, adult emergence is well underway and oviposition is occurring, and early instar larvae may be present and beginning to feed on developing wheat kernels. Low rainfall amounts across large areas of Manitoba and Saskatchewan has resulted in delayed adult emergence, resulting in lower egg densities, according to our model.
Figure 1. Predicted wheat midge (Sitodiplosis mosellana) phenology at Saskatoon SK. Values are based on model simulations (April 1-July 19, 2020).Figure 2. Predicted wheat midge (Sitodiplosis mosellana) phenology at Lacombe AB. Values are based on model simulations (April 1-July 19, 2020).
Figure 3 compares synchrony between wheat midge and wheat development for fields near Saskatoon. The graph indicates that peak adult emergence and oviposition are likely to occur during anthesis; wheat susceptibility decreases once the crop is flowering (Fig. 3). Figure 4 compares the predicted phenology near Saskatoon of wheat midge adults with Macroglenes penetrans, a parasitoid of wheat midge. The parasitoid wasp seeks out and lays eggs in wheat midge eggs. The graph shows that emergence/oviposition of wheat midge adults and M. penetrans are similar (Fig. 4). Taken together, this information can be used as a guide to determine when fields should be monitored.
Figure 3. Comparison of predicted phenology of wheat midge (Sitodiplosis mosellana) and wheat at Saskatoon SKas of July 19, 2020.Figure 4. Comparison of predicted phenology of wheat midge (Sitodiplosis mosellana) and its parasitoid, Macroglenes penetrans, at Saskatoon SK as of July 19, 2020.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat midge model runs indicate that, where wheat midge are present, adult emergence is well underway and oviposition is occurring across most prairie locations. The map suggests that, as of July 12, 2020, populations are primarily in the egg stage (Fig. 1). Low rainfall amounts across large areas of Manitoba and Saskatchewan has resulted in delayed adult emergence, resulting in lower egg densities.
Figure 1. Predicted percent of population of wheat midge (Sitodiplosis mosellana) at adult stage across the Canadian prairies (as of July 12, 2020).
The next 10-14 days are very important for monitoring wheat midge populations for the purpose of making management decisions. Simulations were run to July 26 to assess population development over the next 10 days (Table 1). The following table indicates that 50% emergence of adults should occur this week at Saskatoon and next week at Lacombe (Table 1). This week populations in Manitoba are predicted to be at 90% adult emergence (Table 1).
The two graphs below illustrate the development of wheat midge populations near Saskatoon (Fig. 2) and Lacombe (Fig. 3). Adult numbers are currently peaking near Saskatoon while adult emergence near Lacombe is not expected to peak until next week.
Figure 2. Predicted wheat midge (Sitodiplosis mosellana) phenology at Saskatoon SK projected to July 21, 2020.Figure 3. Predicted wheat midge (Sitodiplosis mosellana) phenology at Lacombe AB projected to July 21, 2020.
The next two graphs compare the synchrony between wheat midge and wheat for fields near Lacombe (Fig. 4). The graph indicates that peak adult emergence and oviposition may occur during anthesis; wheat susceptibility decreases once the crop is flowering (Fig. 4).
Figure 4. Comparison of predicted phenology of wheat midge (Sitodiplosis mosellana) and wheat at Lacombe ABprojected to July 21, 2020.
The last graph compares phenology (Saskatoon) of wheat midge adults with Macroglenes penetrans, a parasitoid of wheat midge (Fig. 5). The parasitoid wasp lays eggs in wheat midge eggs. The graph shows that emergence/oviposition of wheat midge adults and M. penetrans are similar (Fig. 5). This information can be used as a guide to determine when fields should be monitored.
Figure 5. Comparison of predicted phenology of wheat midge (Sitodiplosis mosellana) and its parasitoid, Macroglenes penetrans, at Saskatoon SK projected to July 21, 2020.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat midge overwinter as larval cocoons in the soil. Soil moisture conditions in May and June can have significant impact on wheat midge emergence. Adequate rainfall promotes termination of diapause and movement of larval to the sol surface where pupation occurs. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Elliott et al. (2009) reported that wheat midge emergence was delayed or erratic if rainfall did not exceed 20-30 mm during May. Olfert et al. (2016) ran model simulations to demonstrate how rainfall impacts wheat midge population density. Our wheat midge model (Olfert et al. 2020) indicates that dry conditions may result in: (a) Delayed adult emergence and oviposition, (b) Reduced numbers of adults and eggs.
Wheat midge model runs indicate that, where wheat midge are present, pupation is occurring across Alberta, northwest Saskatchewan and southern Manitoba (Fig. 1). Simulations suggest that, though still less than 15%, adult emergence has begun, most notably across Alberta (Fig. 1). Females lay eggs on developing wheat heads. This typically occurs in evenings when winds are calm. Wheat midge monitoring protocol suggests that wheat fields should be inspected for adults in late June and early July as wheat heads are emerging. The next three weeks are very important for monitoring wheat midge populations for the purpose of making management decisions.
Figure 1. Predicted percent of population of wheat midge (Sitodiplosis mosellana) at adult stage across the Canadian prairies (as of July 5, 2020).
Simulations were run to July 21 to assess population development over the next two weeks (Figs. 2-4). The first graph illustrates development of wheat midge populations near Saskatoon (Fig. 2). Adult emergence has begun and should peak next week, suggesting that monitoring fields for adults should begin in the next few days. Oviposition has just started and larvae will occur soon after.
Figure 2. Predicted wheat midge (Sitodiplosis mosellana) phenology at Saskatoon SK projected to July 21, 2020.
The second graph compares synchrony between wheat midge and wheat for fields near Lacombe (Fig. 3). The graph indicates that adult emergence and oviposition may occur this year when the crop is most susceptible.
Figure 3. Comparison of predicted phenology of wheat midge (Sitodiplosis mosellana) and wheat at Lacombe AB projected to July 21, 2020.
The last graph compares phenology of wheat midge adults near Saskatoon with the phenology of Macroglenes penetrans, a parasitoid of wheat midge (Fig. 4). The parasitioid wasp lays is eggs inside wheat midge eggs. The graph shows that the timing of emergence and oviposition of wheat midge adults is similar to the emergence and oviposition timing of M. penetrans. All of this information can be used as a guide to determine when fields should be monitored.
Figure 4. Comparison of predicted phenology of wheat midge (Sitodiplosis mosellana) and its parasitoid, Macroglenes penetrans, at Saskatoon SK projected to July 21, 2020.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Reminder – Based on fall surveys in 2018, wheat midge populations were expected to be low across most of AB and SK this season. Dry conditions in May and June have resulted in reduced emergence of adult populations across most of SK.
Review last week’s predictive model update (Wk 16) regarding the development for this pest. This week, the percent of adult emergence is depicted across the Canadian prairies as of July 28, 2019 (Fig. 1). The map below predicts the geographic distribution and corresponding accumulation of heat units necessary for wheat midge to emerge from puparia developing in the soil. Midge emergence is 100% complete in areas highlighted red, 90% complete in areas highlighted orange, and ≤50% in areas highlighted light orange or yellow (Fig. 1).
Figure 1. Accumulation of heat units necessary for wheat midge (Sitodiplosis mosellana) to emerge from puparia in the soil and corresponding estimated percent of midge emerged across the Canadian prairies as of July 28, 2019.
Monitoring: When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge: a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage. b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
Wheat midge and its doppelganger, the lauxanid fly, were featured as the Insect of the Week (for Wk10). Check that post for help with in-field scouting for this economic pest of wheat! The differences between midges and parasitoid wasps are featured as the current Insect of the Week (for Wk11). Not all flying insects are mosquitoes nor are they pests – many are important parasitoid wasps that actually regulate insect pest species in our field crops.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Dry conditions in May and June have resulted in reduced emergence of adult populations across most of SK. Oviposition is well underway and larvae should be developing in wheat heads. Where wheat midge are present, the following maps indicate potential occurrence of eggs (Fig. 1) and larvae (present in wheat heads) across the prairies (Fig. 2). It should be noted that, based on fall surveys in 2018, wheat midge populations were expected to be low across most of AB and SK.
Figure 1. Predicted potential occurrence of eggs laid by wheat midge (Sitodiplosis mosellana) across the Canadian prairies (as of July 21, 2019). Figure 2. Predicted potential occurrence of larvae of wheat midge (Sitodiplosis mosellana) across the Canadian prairies (as of July 21, 2019).
Monitoring: When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge: a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage. b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
Wheat midge and its doppelganger, the lauxanid fly, were featured as the Insect of the Week (for Wk10). Check that post for help with in-field scouting for this economic pest of wheat! The differences between midges and parasitoid wasps are featured as the current Insect of the Week (for Wk11). Not all flying insects are mosquitoes nor are they pests – many are important parasitoid wasps that actually regulate insect pest species in our field crops.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Where wheat midge are present, cool, dry conditions in May and June have resulted in delayed emergence of adults. Wheat midge larvae have moved to the soil surface and pupae are appearing. In some locations adults should be beginning to emerge. The wheat midge model predicts that 44% (45% last week) of the population are in the larval cocoon stage and 37% (47% last week) of the population is predicted to have moved to the soil surface. This week 12% (7% last week) is predicted to be in the pupal stage. Adults continue to emerge in localized areas in localized areas across all three provinces.
The first map (Fig. 1) indicates the percent of the population that is in the pupal stage. The second map (Fig. 2) indicates that less than 10% of the adult population has emerged. The last map (Fig. 3) indicates that oviposition may be occurring in localized areas. It should be noted that, based on fall surveys in 2018, wheat midge populations were expected to be low across most of AB and SK.
Figure 1. Predicted percent of wheat midge (Sitodiplosis mosellana) populations at PUPAL STAGE across the Canadian prairies (as of July 15, 2019). Figure 2. Predicted percent of wheat midge (Sitodiplosis mosellana) populations at ADULT STAGE across the Canadian prairies (as of July 15, 2019). Figure 3. Predicted percent of wheat midge (Sitodiplosis mosellana) populations where egg laying has begun across the Canadian prairies (as of July 15, 2019).
Monitoring: When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge: a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage. b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
Wheat midge and its doppelganger, the lauxanid fly, were featured as the Insect of the Week (for Wk10). Check that post for help with in-field scouting for this economic pest of wheat! The differences between midges and parasitoid wasps are featured as the current Insect of the Week (for Wk11). Not all flying insects are mosquitoes nor are they pests – many are important parasitoid wasps that actually regulate insect pest species in our field crops.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Where wheat midge are present, cool, dry conditions have resulted in delayed emergence of adults. Wheat midge larvae have moved to the soil surface and pupae are appearing. In some locations adults should be beginning to emerge. The wheat midge model predicts that 45% (54% last week) of the population are in the larval cocoon stage and 47% (42% last week) of the population is predicted to have moved to the soil surface. This week 7% (3.4% last week) is predicted to be in the pupal stage. Adults have begun to emerge in localized areas in southern AB and MB.
The first map indicates the percent of the population that is in the larval stage, at the soil surface. Midge development in SK was reduced due to dry soil moisture conditions. The second map indicates that pupae may be present in some fields in southern AB and MB. It should be noted that, based on fall surveys in 2018, wheat midge populations were expected to be low across most of AB and SK.
Figure 1. Percent of larval population at the soil surface (as of July 8, 2019) across the Canadian prairies. Figure 2. Percent of population AT PUPAL STAGE (as of July 8, 2019) across the Canadian prairies. Figure 3. Percent of population AT ADULT STAGE (as of July 8, 2019) across the Canadian prairies.
Monitoring: When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge: a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage. b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
Wheat midge and its doppelganger, the lauxanid fly, were featured as the Insect of the Week (for Wk10). Check that post for help with in-field scouting for this economic pest of wheat! The differences between midges and parasitoid wasps are featured as the current Insect of the Week (for Wk11). Not all flying insects are mosquitoes nor are they pests – many are important parasitoid wasps that actually regulate insect pest species in our field crops.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Wheat midge adults generally emerge during the first week of July. Compared to long term normal values for temperature and rainfall, May and June in the Saskatoon region has been approximately 1 °C cooler and rainfall is 40-60% less than normal. Dry conditions in May and June can have significant impact on wheat midge emergence. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Elliott et al (2009) reported that wheat midge emergence was delayed or erratic if rainfall did not exceed 20-30 mm during May. Olfert et al. 2016 ran model simulations to demonstrate how rainfall impacts wheat midge population density. Our wheat midge model indicates that dry conditions may result in:
Delayed adult emergence and oviposition
Reduced numbers of adults and eggs
The wheat midge model indicates that 54% (70% last week) of the population are in the larval cocoon stage and 42% (29% last week) of the population is predicted to have moved to the soil surface. This week 3.4% (less than 1% last week) is predicted to be in the pupal stage. Adults may begin to emerge later this week, or earlier next week.
The first map indicates the percent of the population that is in the larval stage, at the soil surface. The second map indicates that pupae may be present in some fields in southern AB and MB. It should be noted that, based on fall surveys in 2018, wheat midge populations were expected to be low across most of AB and SK.
Figure 1. Percent of larval population at the soil surface (as of July 1, 2019) across the Canadian prairies. Figure 2. Percent of population AT PUPAL STAGE (as of June 24, 2019) across the Canadian prairies.
Monitoring: When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge: a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage. b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
Wheat midge and its doppelganger, the lauxanid fly, were featured as the Insect of the Week (for Wk10). Check that post for help with in-field scouting for this economic pest of wheat! The differences between midges and parasitoid wasps are featured as the current Insect of the Week (for Wk11). Not all flying insects are mosquitoes nor are they pests – many are important parasitoid wasps that actually regulate insect pest species in our field crops.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Wheat midge and its doppelganger, the lauxanid fly, were featured as the Insect of the Week (for Wk10). Check that post for help with in-field scouting for this economic pest of wheat! The differences between midges and parasitoid wasps are featured as the current Insect of the Week (for Wk11). Not all flying insects are mosquitoes nor are they pests – many are important parasitoid wasps that actually regulate insect pest species in our field crops.
Wheat midge adults generally emerge during the first week of July. Compared to long term normal values for temperature and rainfall, May and June in the Saskatoon region has been approximately 1 °C cooler and rainfall is 40-60% less than normal. Dry conditions in May and June can have significant impact on wheat midge emergence. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Elliott et al (2009) reported that wheat midge emergence was delayed or erratic if rainfall did not exceed 20-30 mm during May. Olfert et al. 2016 ran model simulations to demonstrate how rainfall impacts wheat midge population density. Our wheat midge model indicates that dry conditions may result in:
Delayed adult emergence and oviposition
Reduced numbers of adults and eggs
The wheat midge model indicates that 70% (82% last week) of the population are in the larval cocoon stage and 29% (18% last week) of the population is predicted to have moved to the soil surface. The first map presents wheat midge development as of last week (Fig. 1).
Figure 1. Percent of larval population at the soil surface (as of June 17, 2019) across the Canadian prairies.
Results indicate that dry conditions delayed development of larval cocoons in SK. Adequate precipitation in AB and MB should have resulted in movement of larvae to the soil surface. The model indicates that recent rain has resulted in larval development (larval cocoons) across SK.The second map indicates that recent rain in SK should result in development of larval cocoons and subsequent movement of larvae to the soil surface (Fig. 2). The third map (Fig. 3) indicates that pupae may be present in some fields in southern AB and MB.It should be noted that, based on fall surveys in 2018, wheat midge populations were expected to be low across most of AB and SK.
Figure 2. Percent of larval population at the soil surface (as of June 24, 2019) across the Canadian prairies. Figure 3. Percent of population AT PUPAL STAGE (as of June 24, 2019) across the Canadian prairies.
Monitoring: When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge: a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage. b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Wheat midge adults generally emerge during the first week of July. Compared to long term normal values for temperature and rainfall, May and June in the Saskatoon region has been approximately 1 °C cooler and rainfall is 40-60% less than normal. Dry conditions in May and June can have significant impact on midge emergence. Elliott et al (2009) reported that wheat midge emergence was delayed or erratic, if rainfall did not exceed 20-30 mm during May.
Olfert et al. 2016 ran model simulations to demonstrate how rainfall impacts wheat midge population density. Two simulations were run to demonstrate the impact of rainfall and temperature on adult emergence and oviposition. The first graph illustrates adult emergence and oviposition based on long term (climate) data for Saskatoon (Fig. 1). The model indicates that emergence should begin in early July with oviposition beginning a few days later.
Figure 1. Predicted adult emergence and oviposition of wheat midge (Sitodiplosis mosellana) based on LONG TERM DATA for Saskatoon SK.
The second graph (Fig. 2) shows how DRYER, COOLER conditions would result in:
Delayed adult emergence and oviposition.
Reduced numbers of adults and eggs.
Figure 2. Predicted adult emergence and oviposition of wheat midge (Sitodiplosis mosellana) using LONG TERM DATA manipulated to both DRYER and COOLER conditions for Saskatoon SK.
Monitoring: When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active.
On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (Fig. 3).
Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads.
Inspect the field daily in at least 3 or 4 locations during the evening.
Figure 3. Adult wheat midge (Sitodoplosis mosellana) active on wheat head at anthesis stage (Photo: AAFC-Beaverlodge; S. Dufton and A. Jorgensen).
REMEMBER in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember the parasitoid, Macroglenes penetrans (Fig. 4), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill beneficial insects that help regulate midge populations.
Figure 4. The tiny parasitoid wasp, Macroglenes penetrans, is synchronized to emerge when wheat midge adults are present and the wasp seeks and oviposits on wheat midge eggs (Photo: AAFC-Beaverlodge; S. Dufton).
Economic Thresholds for Wheat Midge:
a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
The case of the innocuous versus the evil twin: When making pest management decisions, be sure that the suspect is actually a pest. This can be challenge since insects often mimic each other or look very similar. An insect that looks, moves and acts like a pest may in fact be a look-alike or doppelganger.
Doppelgangers may be related (e.g. same genus) or may not be related, as in the case of monarch butterflies (Danaus plexippus) and viceroys (Limenitis achrippus). Doppelgangers are usually relatively harmless but sometimes the doppelganger is a pest yet their behaviour, lifecycle or hosts may be different.
Correctly identifying a pest enables selection of the most accurate scouting or monitoring protocol. Identification and monitoring enables the application of economic thresholds. It also enables a producer to select and apply the most effective control option(s) including method and timing of application. For the rest of the growing season, the Insect of the Week will feature insect crop pests and their doppelgangers.
The case of the wheat midge vs. Lauxanid fly:Wheat midge larvae, in high enough numbers, can significantly reduce yield and quality of a wheat crop. The time to control this pest is at the adult stage. The key to determining whether adult numbers exceed the economic threshold for control is to follow the recommended insect pest monitoring protocol.
One hiccup is that it can be easy to mistake lauxanid flies for wheat midge adults when doing in-field scouting. But their size, general body shape and colour differences will help enable a person to tell them apart.
Wheat midge:
Thinner “mosquito-like” body (Image 1, left)
Long, thin legs
Between 1.5- 2 mm long
Dark, vibrant orange when alive
Large, black eyes that proportionally make up approximately 9/10’s of head
Lauxanid fly:
Bulkier body (Image 1, right)
Shorter, compact legs
Between 2 and 4 mm long
Paler, less vibrant orange colour
Smaller eyes that may be black, brown or red. Eyes proportionally make up approximately ½ of head
Image 1: Wheat midge (left) and Lauxanid (right). Photo Credit: Bob Elliott (ret.), AAFC
Wheat midge larvae (Image 2) will feed on developing wheat kernels and can be found inside the wheat head. Lauxaniid larvae are not recorded as pests of any field crop and tend to be found in decaying leaf litter. Wheat midge larvae can be identified by their bright orange colour, and presence of spatula structure (Fig. 2; y-shaped structure circled below).
Economically significant insect pests are monitored across the Canadian prairies each year, thanks to extensive networks of collaborators and cooperators. In 2018, that effort culminated in 5764 survey stops across Manitoba, Saskatchewan, Alberta and the BC Peace!
Here’s what’s included in the PDF file:
Average tempature, average precipitation, and modeled soil moisture for 2018.
A series of geospatial maps are included for each of the target species; the current map is followed by the previous 4 years.
For some species, the geospatial maps represent 2018 distributions used to infer risk in the coming 2019 growing season. Data is included for bertha armyworm, cabbage seedpod weevil, pea leaf weevil, wheat stem sawfly and diamondback moth.
For wheat midge and grasshoppers, the geospatial maps forecast or predict expected populations or risk for the 2019 growing season.
These maps help the agricultural industry prepare to manage insect pests across the prairies and helps growers make crop choices and anticipate scouting priorities within their growing region. From May to July, the Weekly Updates will provide in-season updates, predictive model outputs plus scouting tips and links to relevant information.
Thank you to the many people who monitor each growing season!
Wheat Midge (Sitodiplosis mosellana) – Warm, moist conditions in Manitoba are predicted to be favourable for development wheat midge larvae (Fig. 1A). In Manitoba and eastern Saskatchewan larvae should be dropping into the soil (Fig. 1B).
Figure 1. Percent wheat midge in the early larval stage (A) and larval cocoons (B) based on model simulations for April 1 – July 23, 2018.
Model runs for Saskatoon indicate the midge development, due to dryer conditions in June, is slower than predicted emergence at Brandon and Edmonton (Fig. 2).
Figure 2. Predicted wheat midge phenology at Brandon, Saskatoon and Edmonton. Values are based on model simulations, for April 1 – July 16, 2018.
Monitoring:
When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge:
a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011. Additionally, more information can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – The warm, moist conditions in Manitoba are predicted to be favourable for emergence of adults (Fig. 1) while dry conditions in Alberta and Saskatchewan should result in reduced emergence (Fig. 2).
Figure 1. Predicted wheat midge emerged based on degree-days accumulated across the Canadian prairies (as of July 15, 2018).Figure 2. Percent wheat midge in the early larval stage based on model simulations for April 1 – July 16, 2018.
In Manitoba and eastern Saskatchewan, populations should be primarily in the early larval stage (80%). Model runs for Saskatoon indicate the midge development, as a result of dryer conditions in June, is slower than predicted emergence at Brandon and Edmonton (Fig. 3).
Figure 3. Predicted wheat midge phenology at Brandon, Saskatoon, and Edmonton. Values are based on model simulations, for April 1 – July 16, 2018.
Monitoring:
When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge:
a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage. b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011. Additionally, more information can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – As of July 9, 2018, the model runs indicate that wheat midge oviposition is well underway across a large area of Manitoba and Saskatchewan. Populations in this region are primarily in the egg stage (Fig. 1) with larvae appearing as well.
Figure 1. Percent wheat midge in the egg stage based on model simulations for April 1 – July 9, 2018.
Monitoring:
When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge:
a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011. Additionally, more information can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – As of July 2, 2018, the warm, moist conditions in Manitoba are predicted to be favourable for emergence of wheat midge adults, while dry conditions in Alberta and Saskatchewan should result in delayed emergence (Fig. 1). Some populations may have greater than 50% emergence. Oviposition is predicted to have begun and larvae may be appearing in wheat heads.
Figure 1. Percent wheat midge adult emergence based on model simulations for April 1-July 2, 2018.
Model runs for Saskatoon SK (Fig. 2) indicate the midge emergence is slower than predicted emergence at Brandon MB (Fig. 3). The delay in midge emergence is related to dryer dryer conditions in June 2018 in Saskatchewan.
Figure 2. Predicted wheat midge phenology for April 1-July 2, 2018, at Saskatoon SK. Figure 3. Predicted wheat midge phenology for April 1-July 2, 2018, at Brandon MB.
Monitoring:
When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge:
a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011. Additionally, more information can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – As of June 24, 2018, the recent dry conditions near Saskatoon SK have resulted in delayed emergence of adult wheat midge (Figs. 1 and 2). Predictions for 2018 are similar to average values (Figs. 2 and 3).
Figure 1. Predicted wheat midge emerged based on degree-days accumulated across the Canadian prairies (as of June 24, 2018).Figure 2. Predicted wheat midge phenology at Saskatoon SK. Values are based on model simulations for April 1 – June 24, 2018. Model projections to July 15 are based on long term climate normal values for temperature and precipitation.Figure 3. Predicted wheat midge phenology at Saskatoon SK. Values are based on model simulations for Long Term Climate Normals (LTCN). Model projections to July 15 are based on long term climate normal values for temperature and precipitation.
Monitoring:
When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge:
a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011. Additionally, more information can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Recent dry conditions near Saskatoon have resulted in slower wheat midge development (compared to last week’s model output). Predictions for 2018 (Fig. 1) are similar to long term average values (Fig. 2).
Figure 1. Predicted wheat midge phenology at Saskatoon SK. Values are based on model simulations for April 1 – June 18, 2018.Figure 2. Predicted wheat midge phenology at Saskatoon SK. Values are based on model simulations for Long Term Climate Normals.
Monitoring:
When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge:
a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
The 2018 wheat midge forecast map was circulated in January and is posted below for reference. Note that areas highlighted orange or red in the map below included surveyed fields with comparatively higher densities of wheat midge cocoons last fall.
Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011. Additionally, more information can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Simulation modelling is used to predict wheat midge emergence across the Canadian prairies. The wheat midge model indicates that wheat midge larvae should be moving to the soil surface (Fig. 1). Adequate moisture has resulted in expected emergence patterns.
Figure 1. Predicted wheat midge phenology at Saskatoon SK. Values are based on model simulations, for April 1 – June 11, 2018 (projected to July 15, 2018).
The 2018 wheat midge forecast map was circulated in January and is posted below for reference. Note that areas highlighted orange or red in the map below included surveyed fields with comparatively higher densities of wheat midge cocoons last fall.
Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry). A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011. Additionally, more information can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat surveying – As wheat is harvested, monitoring can begin for two wheat pests including wheat midge and wheat stem sawfly. As soon as the combine passes through, in-field monitoring can commence with: ● Soil core sampling is used to assess the densities of wheat midge cocoons set to overwinter, PLUS ● The number of cut stems can be counted to determine the density of wheat stem sawfly.
By January, forecast and risk maps summarizing surveying efforts for the above pests will be available (e.g., check the Risk Map Page).
More information about these pests can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages or ONLY the Wheat stem sawfly pages. Remember the entire guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat surveying – As wheat is harvested, monitoring can begin for two wheat pests including wheat midge and wheat stem sawfly. As soon as the combine passes through, in-field monitoring can commence with: ● Soil core sampling is used to assess the densities of wheat midge cocoons set to overwinter, PLUS ● The number of cut stems can be counted to determine the density of wheat stem sawfly.
By January, forecast and risk maps summarizing surveying efforts for the above pests will be available (e.g., check the Risk Map Page).
More information about these pests can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages or ONLY the Wheat stem sawfly pages. Remember the entire guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Reminder – The previous Insect of the Week (Week 7) features wheat midge!
Model output indicates that the emergence of adults is well underway across the prairies. Oviposition should be underway and larvae should be present. Dry conditions in Saskatchewan appear to have reduced potential adult emergence.
Monitoring: When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis. In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge: a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage. b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled. Inspect the developing kernels for the presence of larvae and the larval damage.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Reminder – The previous Insect of the Week (Week 7) features wheat midge!
Model output indicates that wheat midge adult emergence has begun across the prairies. Cooler, dryer conditions in 2017 have resulted in lower emergence than the same time last year. Elliott et al. (2009) reported that adult emergence was delayed by inadequate rainfall amounts (May and June). The model was parameterized to take rainfall into account. Model output indicates that midge emergence across most of SK has been limited by inadequate rainfall during June.
Monitoring: When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis. In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge: a)To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage. b)For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled. Inspect the developing kernels for the presence of larvae and the larval damage.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Reminder – The previous Insect of the Week (Week 7) features wheat midge! Simulation modelling is used to predict wheat midge emergence across the Canadian prairies. Predicted adult emergence for Saskatoon and Melfort is very similar to last week. Elliott et al. (2009) reported that adult emergence was affected by inadequate rainfall amounts (May and June). The model was parameterized to take rainfall into account. Output indicates that emergence at Saskatoon has been limited by inadequate rainfall during June. Rainfall for Saskatoon in June was 37 mm compared to long-term average of 61 mm. Emergence at Melfort is predicted to be more advanced. June rainfall was 61 mm.
Monitoring: When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis. In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge: a)To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage. b)For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled. Inspect the developing kernels for the presence of larvae and the larval damage.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Reminder – The previous Insect of the Week (Week 7) features wheat midge! Simulation modelling is used to predict wheat midge emergence across the Canadian prairies. The model has not changed significantly from last week. The map below predicts the geographic distribution and corresponding accumulation of heat units necessary for wheat midge to emerge from puparia developing in the soil.
Monitoring: When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis. In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge: a)To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage. b)For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled. Inspect the developing kernels for the presence of larvae and the larval damage.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
This week’s Insect of the Week is a beneficial wasp from the Family Pteromalidae named Macroglenes penetrans. It is an important natural enemy of wheat midge. The wasp is a parasitoid that lives within the wheat midge larva and overwinters within the host. In the spring, the parasitoid larva develops to emerge from the wheat midge cocoon buried in the soil and seeks out wheat midge eggs.
For more information about M. penetrans, see our Insect of the Week page.
Macroglenes penetrans – adult (AAFC)
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Wheat Midge (Sitodiplosis mosellana) – Reminder – The previous Insect of the Week (Week 7) features wheat midge!
Simulation modelling is used to predict wheat midge emergence across the Canadian prairies. The model has not changed significantly from last week. The map below predicts the geographic distribution and corresponding accumulation of heat units necessary for wheat midge to emerge from puparia developing in the soil.
Monitoring: When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis. In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge:
a)To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b)For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
This week’s Insect of the Week is the wheat midge. Larvae feed on the surface of developing wheat kernels in spring and winter wheat, durum wheat, triticale and occasionally spring rye. Damage includes aborted, shrivelled, misshapen, cracked, or scared kernels. This lowers grain yield, quality and grade.
For more information on the wheat midge, visit our Insect of the Week page.
Wheat Midge (Sitodiplosis mosellana) – TheInsect of the Week features wheat midge!
Simulation modelling is used to predict wheat midge emergence across the Canadian prairies. The model predicted that wheat midge adults should emerge in July. The following graphs indicate that adult emergence at Saskatoon (Fig. 1) could be two weeks later than at Melfort (Fig. 2). Though average temperatures have been similar for both locations, model output indicates that dry conditions at Saskatoon (6 mm since June 1) may result in delayed emergence. Adequate moisture at Melfort (20 mm since June 1) has resulted in expected emergence patterns. Predicted rainfall for this week should result in emergence patterns that are more typical.
Figure 1. Predicted wheat midge development at Saskatoon SK.
Figure 2. Predicted wheat midge development at Melfort SK.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Predictive modelling will be used again to help forecast wheat midge emergence across the Canadian prairies.
The wheat midge model indicates that midge larvae should be at the soil surface this week. However, sub-optimal rainfall amounts may result in delayed emergence of adults.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Predictive modelling will be used again to help forecast wheat midge emergence across the Canadian prairies. The maps below predicts the geographic distribution and corresponding accumulation of heat units necessary for wheat midge to emerge from puparia developing in the soil.
Since last week, the wheat midge model indicates that wheat midge larvae should be moving to the soil surface this week and the adult emergence has been delayed by 5-7 days (i.e., now predicted to start the first week of June).
Review the 2017 wheat midge forecast map circulated in January by accessing the Risk and Forecast Maps Post.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Predictive modelling will be used again to help forecast wheat midge emergence across the Canadian prairies. The maps below predicts the geographic distribution and corresponding accumulation of heat units necessary for wheat midge to emerge from puparia developing in the soil.
For the week of May 24, 2017, soil moisture and temperature conditions appear to be conducive for wheat midge development. The wheat midge model indicates that wheat midge larvae should be moving to the soil surface by the end of May.
Reminder – Back in January, the 2017 Wheat midge forecast map was released along with the other Risk and Forecast maps. It’s posted again below for reference.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
The 2017 Prairie-Wide Risk and Forecast Maps can be viewed and downloaded here. Maps are generated for bertha armyworm, grasshoppers, wheat midge, cabbage seedpod weevil, pea leaf weevil, wheat stem sawfly, diamondback moth as well as average temperature, average precipitation, and modeled soil moisture for the Canadian prairies.
Thank you to the many people who monitor each growing season! An astonishing 6414 survey stops were involved in the insect monitoring performed across the Canadian prairies in 2016!
All the Saskatchewan Insect Survey and Forecast Maps and more can be found on Saskatchewan.ca ! To view all our agriculture maps check out our Maps for Farmers and Agribusiness section.
Alberta has posted their forecast and survey maps for several insect pest species occurring in field crops. Visit their home page to view all the Alberta maps.
The following list and hyperlinks were provided by Shelley Barkley via the Alberta Insect Pest Monitoring Network.
Scott Meers, entomologist with Alberta Agriculture and Forestry, was interviewed and spoke about Alberta insect forecasts for 2017. That series of five interviews can be access with the following hyperlinks:
Additionally, Alberta Agriculture and Forestry has updated their webpages with the following:
They have created a graphic that illustrates the “range expansion” of 2 evil weevils in Alberta: pea leaf and cabbage seedpod.
Similar graphics have been added to their bertha armyworm page. Check out the past “six years of bertha armyworm moth” in Alberta which can be accessed via an hyperlink positioned on their bertha armyworm web page.
Their grasshopper page has been updated too – check out the “historic grasshopper maps” for Alberta via a hyperlinklocated on their grasshopper web page.
The past “eight years of sawfly” in Alberta can be accessed via a hyperlink located on their wheat stem sawfly web page.
Each fall, soil core sampling is carried out across the Canadian prairies to assess wheat midge densities and parasitism levels of the overwintering cocoon stage. Soil collected from wheat fields is collected then the samples are washed to retrieve the tiny cocoons, each measuring only ~2-3mm in diameter (Fig. 1).
After washing, each cocoon is carefully dissected under the microscope to determine if a parasitoid larva has attacked the wheat midge larval host. The densities of the cocoons, and the percent parasitism by the biological control agents (Macroglenes penetrans, Platygaster sp., Euxestonotus error), are compiled and used to generate the geospatial forecast map below.
The Albertan 2017 wheat midge forecast is posted below (Fig. 2) and you can review previous maps for that province further down the page. Be sure to review Alberta Agriculture & Forestry’s full wheat midge forecast map posting and how they conduct their survey by linking here.
Figure 2. Alberta wheat midge forecast map for 2017.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Predictive modelling will be used again to help forecast wheat midge emergence across the Canadian prairies. The map below predicts the geographic distribution and corresponding accumulation of heat units necessary for wheat midge to emerge from puparia developing in the soil.
Monitoring: When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis. In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge: a)To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage. b)For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
Wheat growers in Alberta can access mapped cumulative counts from wheat midge pheromone traps. A screen shot of the map is provided below (retrieved August 3, 2016).
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Predictive modelling will be used again to help forecast wheat midge emergence across the Canadian prairies. The map below predicts the geographic distribution and corresponding accumulation of heat units necessary for wheat midge to emerge from puparia developing in the soil.
Monitoring: When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis. In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge: a)To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage. b)For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
Wheat growers in Alberta can access mapped cumulative counts from wheat midge pheromone traps. A screen shot of the map is provided below (retrieved 27Jul2016).
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Predictive modelling will be used again to help forecast wheat midge emergence across the Canadian prairies. The map below predicts the geographic distribution and corresponding accumulation of heat units necessary for wheat midge to emerge from puparia developing in the soil.
Monitoring: When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
Economic Thresholds for Wheat Midge: a)To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage. b)For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
Wheat growers in Alberta can access mapped cumulative counts from wheat midge pheromone traps. A screen shot below confirms that wheat midge are flying beyond the predicted model mapped above.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Predictive modelling will be used again to help forecast wheat midge emergence across the Canadian prairies. The map below predicts the geographic distribution and corresponding accumulation of heat units necessary for wheat midge to emerge from puparia developing in the soil.
Monitoring: When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (shown below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads. Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
Economic Thresholds for Wheat Midge: a)To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b)For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
Wheat growers in Alberta can access mapped cumulative counts from wheat midge pheromone traps. A screen shot below confirms that wheat midge are flying beyond the predicted model mapped above.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Wheat Midge (Sitodiplosis mosellana) – Predictive modelling will be used again to help forecast wheat midge emergence across the Canadian prairies. The map below predicts the geographic distribution and corresponding accumulation of heat units necessary for wheat midge to emerge from puparia developing in the soil.
Wheat Midge (Sitodiplosis mosellana) – Predictive modelling will be used again to help forecast wheat midge emergence across the Canadian prairies. The maps below predicts the geographic distribution and corresponding accumulation of heat units necessary for wheat midge to emerge from puparia developing in the soil.
For the week of May 23, 2016, model runs for Saskatoon SK and Fairview AB presented similar results. Unlike last year when dry soil moisture limited development, soil moisture conditions appear to be suitable for wheat midge development in the soil. Output indicates that larvae should be moving to the soil surface later this week.
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Prairie Pest Monitoring Network Weekly Updates – July 15, 2015
Otani, Giffen, Svendsen, Olfert
Greetings! This week grasshoppers, cabbage seedpod weevil and wheat midge were important pests based on provincial reports and reminders for in-field scouting. Rain fell in some areas of the prairies but many continue to wait for moisture. Remember, a downloadable version of this Weekly Update can beaccessed here.
Weather synopsis – Thanks to the folks who compile and manage the agroclimate maps posted by AAFC! The map below shows the Accumulated Precipitation the past 7 days (i.e., July 7-13, 2015):
While the map below reflects the Accumulated Precipitation for the Growing Season (i.e., April 1-July 13, 2015):
The map below reflects the Percent of Normal Precipitation for the Growing Season (i.e., April 1-July 13, 2015) for comparison:
The map below shows the Lowest Temperatures the Past 7 Days (July 7-13, 2015) across the prairies:
While the map below shows the Highest Temperatures the Past 7 Days (July 7-13, 2015) across the prairies:
The updated growing degree day (GDD) (Base 5ºC, March 1 – July 12, 2015) map is below:
While the growing degree day (GDD) (Base 10ºC, March 1 – July 12, 2015) map is included below:
Bertha armyworm (Mamestra configurata) –Low cumulative counts of BAW moths were again reported in pheromone traps throughout the prairies this week.
Growers in Alberta can refer to the live 2015 Bertha armyworm map which is posted by Alberta Agriculture and Forestry that reflects cumulative counts of moths intercepted.
Growers in Manitoba can refer to the latest Insect and Disease Report (updated July 10, 2015) for BAW cumulative count updates.
In-field monitoring for egg masses (Refer to photo below) and newly emerged larvae (photo below) should initially focus on the undersides of leaves plus watch the margins of leaves for feeding. Bertha armyworm larvae will also feed on newly developing pods so the whole plant should be examined. Watch for the following life stages:
Reminder: Some bertha armyworm larvae remain green or pale brown throughout their larval life. Large larvae may drop off the plants and curl up when disturbed, a defensive behavior typical of cutworms and armyworms. Young larvae chew irregular holes in leaves, but normally cause little damage. The fifth and sixth instars cause the most damage by defoliation and seed pod consumption. Crop losses due to pod feeding will be most severe if there are few leaves. Larvae eat the outer green layer of the stems and pods exposing the white tissue. At maturity, in late summer or early fall, larvae burrow into the ground and form pupae.
Monitoring:
Larval sampling should commence once the adult moths are noted. Sample at least three locations, a minimum of 50 m apart. At each location, mark an area of 1 m2 and beat the plants growing within that area to dislodge the larvae. Count them and compare the average against the values in the economic threshold table below:
Table 1. Economic thresholds for Bertha armyworm in canola (courtesy Manitoba Agriculture, Food and Rural Initiatives).
Expected Seed Value – $ / bushel*
Spraying cost –
$ / acre
6
7
8
9
10
11
12
13
14
15
16
Number of Larvae / metre2 *
7
20
17
15
13
12
11
10
9
9
8
8
8
23
20
17
15
14
13
11
11
10
9
9
9
26
22
19
17
16
14
13
12
11
10
10
10
29
25
22
19
17
16
14
13
12
11
11
11
32
27
24
21
19
17
16
15
14
13
12
12
34
30
26
23
21
19
17
16
15
14
13
13
37
32
28
25
22
20
19
17
16
15
14
14
40
35
31
27
24
22
20
19
17
16
15
15
43
37
32
29
26
23
22
20
19
17
16
* Economic thresholds for bertha armyworm are based on an assumed yield loss of 0.058 bu/acre for each larva/metre2 (Bracken and Bucher. 1977. Journal of Economic Entomology. 70: 701-705).
Grasshoppers (Camnulla pellucida, Melanoplus sanguinipes, M. bivittattus, M. packardii) – In-field scouting along field margins and in ditches AND within the field is critical now with the exceedingly dry growing conditions!
Scouting – Remember only five or six grasshopper species of the 80+ that occur on the prairies are regarded as crop pests. The lifecycles of these six economically important species are similar. Nymphs hatch from overwintered eggs in the spring. Nymphs develop through five stages or instars before becoming adults. Typically, the most serious economic damage will occur from the third to fifth instar stages but all stages need to be monitored. The life stages of the clearwinged grasshopper (Camnulla pellucida) are shown below. Note that adults possess fully formed wings that extend the entire length of the abdomen.
Life stages of the clearwinged grasshopper include (left to right) eggs which overwinter, first instar nymphs that hatch in the spring followed by second, third, fourth and fifth instar nymphs which finally develop into the adult stage.
Need help distinguishing grasshopper nymph stages? Saskatchewan Agriculture’s latest Insect Update includes line drawings to help! It also includes a summary of economic thresholds for grasshoppers in various crops.
Diamondback Moth (Plutella xylostella) – In-field monitoring for DBM larvae should continue this week.
Larval Monitoring:
Once the diamondback moth is present in the area, it is important to monitor individual canola fields for larvae. Remove the plants in an area measuring 0.1 m2 (about 12″ square), beat them on to a clean surface and count the number of larvae dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.
Remember, parasitoid wasps attacking DBM larvae (Refer to photo below) are already present in fields. Use the economic thresholds to preserve these beneficial wasps by NOT applying insecticide until DBM larval densities exceed the threshold.
Diamondback larva (upper left) and pupal silk cocoon (upper right), Diadegma insulare adult and early instar Diamondback moth larvae on canola leaf (lower left) and D. insulare pupae (N=2) within Diamondback moth pupal silk cocoons (lower right).
Economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1 m2 (approximately 2-3 larvae per plant). Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m2 (approximately 1-2 larvae per plant).
Wheat Midge (Sitodiplosis mosellana) – This season, predictive modelling was used in an attempt to forecast wheat midge emergence. In 2014, the degree-day model proposed by German researchers (Basedow) was used to predict adult midge emergence in the Peace River region compared to the 5°C base temperature model which corresponds well to midge emergence throughout central and southern areas of the prairies. The map below predicts the geographic distribution and corresponding accumulation of heat units necessary for wheat midge to emerge from puparia developing in the soil.
The map below indicates the predicted status of wheat midge emergence with 10% of resident midge population emerged in areas highlighted yellow (600-693 DD), 50% in areas highlighted gold (693-784 DD), and 90% of resident midge emerged in areas highlighted orange (784-874 DD) using current weather data (up to July 12, 2015). Wheat midge emergence is predicted to be 100% completed (as of July 12, 2015) with the initial midge larvae now expected to be found within wheat heads growing in southern Alberta, southeast Saskatchewan, southwest Manitoba and to the south of Winnipeg. Wheat midge emergence is predicted to be 90% completed (as of July 12, 2015) throughout most of the boreal region of the prairies and in the north Peace. Wheat midge emergence is predicted to be 50% completed (as of July 12, 2015) throughout the remaining portions of the prairies.
When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis. Additional wheat midge biology and monitoring information can be located by clicking here or linking to your provincial fact sheet (Saskatchewan Agricultureor Alberta Agriculture and Forestry). More information related to wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.
REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (shown below), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.
In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads. Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.
Economic Thresholds for Wheat Midge:
To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.
Inspect the developing kernels for the presence of larvae and the larval damage.
Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Refer to figure below). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than the males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelterbelts, deciduous and conifer forests. They emerge in the spring once temperature reaches 10-5ºC and are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals.
Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the mid vein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching.
Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Refer to figure below). When the larva completes its growth, it drops to the ground and pupates in the soil.
Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 – 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.
Cereal leaf beetle adult (left) and larva (right).
Leaf damage resulting from feeding by cereal leaf beetle larvae.
Monitoring:
Give priority to following factors when selecting monitoring sites:
□ Choose fields and sections of the fields with past or present damage symptoms.
□ Choose fields that are well irrigated (leaves are dark green in color), including young, lush crops. Areas of a field under stress and not as lush (yellow) are less likely to support CLB.
□ Monitor fields located along riparian corridors, roads and railroads.
□ Survey field areas situated near brush cover or weeds, easy to access, or are nearby sheltered areas such as hedge rows, forest edges, fence lines, etc.
Focus your site selection on the following host plant priorities:
● First – winter wheat. If no winter wheat is present then;
● Second – other cereal crops (barley, wheat, oats, and rye). If no cereal crops are present then;
● Third – hay crops. If no hay crops or cereal crops are present then;
● Fourth – ditches and water corridors
Sweep-net Sampling for Adults and Larvae:
A sweep is defined as a one pass (from left to right, executing a full 180 degrees) through the upper foliage of the crop using a 37.5 cm diameter sweep-net. A sample is defined as 100 sweeps taken at a moderate walking pace collected 4-5 meters inside the border of a field. At each site, four samples should be collected, totaling 400 sweeps per site. The contents of each sample should be visually inspected for life stages of CLB and all suspect specimens should be retained for identification. Please note that, because the CLB larvae are covered in a sticky secretion, when they are caught in a sweep-net they are often covered in debris and are very difficult to see. To help determine the presence of CLB, place the contents of the sweep net into a large plastic bag for observation.
Visual Inspection:
Both the adults and larvae severely damage plants by chewing out long strips of tissue between the veins of leaves, leaving only a thin membrane. When damage is extensive, leaves turn whitish (Figure 14). The plant may be killed or the crop may be seriously reduced. In addition to feeding damage, inspectors should be looking for all life stages of the CLB. In a field of host material the visual survey should be conducted between “sweep samples”. Other locations to be examined include grass covered ditch banks and young host crops that are too low to sweep. Experienced surveyors should spend 15 minutes on visual inspection. Less experience surveyors should spend an additional 10 minutes on the visual component.
Swede midge (Contarinia nasturtii) – Reminder – This season we again include scouting tips for in-field monitoring:
□ Watch for unusual plant structures and plant discolourations then follow-up by closely scrutinizing the plant for larvae (Refer to Figure below).
□ The growing tip may become distorted and produce several growing tips or none at all, young leaves may become swollen, crinkled or crumpled and brown scarring caused by larval feeding may be seen on the leaf petioles and stems.
□ Flowers may fail to open.
□ Youngplants that show unusual growth habits should be examined carefully for damageand larvae, especially if the sticky liners have many flies resembling midges (swede midges are about the size of orange blossom wheat midge but are not orange).
□ Larvae can be seen with a hand lens.
In 2014, Canola School posted a swede midge update entitled “ Swede midge a pest on the rise”, featuring Dr. Julie Soroka (AAFC-Saskatoon). The Ontario Canola Growers post swede midge information here. Dr. Rebecca Hallett has posted a very helpful swede midge identification guide for those performing in-field monitoring and pheromone trapping. Finally, canola management recommendations for swede midge in Ontario are posted by Rebecca Hallett and Brian Hall.
Cabbage seedpod weevil (Ceutorhynchus obstrictus) – There is one generation of CSPW per year and the overwintering stage is the adult which is an ash-grey weevil measuring 3-4mm long (Refer to lower left photo). Adults typically overwinter in soil beneath leaf litter within shelter belts and roadside ditches. They emerge from overwintering in the spring as soil temperatures warm to ~15°C. CSPW utilize several flowering hosts including wild mustard, flixweed, hoary cress, stinkweed and volunteer canola. CSPW move to canola during the bud to early flower stages and will feed on pollen and buds, causing flowers to die. Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss. Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo). Eggs are oval and an opaque white, each measuring ~1mm long. Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.
There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo). The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds. A single larva consumes about 5 canola seeds. The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell. Approximately 10 days later, the new adult emerges to feed on maturing canola pods. Later in the season these new adults migrate to overwintering sites beyond the field.
Monitoring: Begin sampling when the crop first enters the bud stage and continue through the flowering. Sweep net samples should be taken at ten locations within the field with ten 180° sweeps per location. Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field. Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur. An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). Consider making insecticide applications late in the dayto reduce the impact on pollinators. Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators. High numbers of adults in the fall may indicate the potential for economic infestations the following spring.
Cabbage root maggot (Delia spp.) – Among root feeding pests of canola, historically five species of Delia flies have been identified across the Canadian prairies; Delia radicum (L.), D. floralis (Fallén), D. platura (Meigan), D. planipalpis (Stein), and D. florilega (Zett.) have been observed in canola over 30 years of research (Liu and Butts 1982, Griffiths 1986a, Broatch and Vernon 1997; Soroka and Dosdall 2011). A summary of root maggot biology, research, and pest management recommendations for canola production was published by Soroka and Dosdall (2011).
Root maggots continue to be a problematic in canola production largely owing to the fact that (i) the species is composition varies by geographic latitude and local conditions, plus (ii) one or two generations per year will occur but varies by species. The species complex is typically characterized by multiple, overlapping generations of Delia resulting in adults laying eggs in canola (Refer to upper left photo for adult and eggs) from late Spring to October and maggots feeding on roots from late rosette until late fall (Refer to upper right photo). Root maggots pupate and overwinter within cigar-shaped, reddish-brown puparia 5-20 cm below the soil surface (Soroka and Dosdall 2011) so canola-on-canola rotations should be avoided. In the spring, adults emerge from mid-May to mate and females lay oval, white eggs singly or in batches near the base of cruciferous host plants over a 5-6 week period. The larvae develop through three instar stages which feed on root hairs then secondary roots initially whereas older maggots will feed into the taproot of a canola plant.
Remember there is no registered insecticide for root maggot control in canola.
Lygus bugs (Lygus spp.) – The economic threshold for Lygus in canola is applied at late flower and early pod stages. Biological and monitoring information can be linked by clicking here or you can access the Manitoba, or Alberta fact sheets or the Prairie Pest Monitoring Network’s monitoring protocol.
Adult L. lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
Fifth instar lygus bug nymph (3-4 mm long) (photo: AAFC-Saskatoon).
Damage: Lygus bugs have piercing-sucking mouthparts and physically damage the plant by puncturing the tissue and sucking plant juices. The plants also react to the toxic saliva that the insects inject when they feed. Lygus bug infestations can cause alfalfa to have short stem internodes, excessive branching, and small, distorted leaves. They feed on buds and blossoms and cause them to drop. They also puncture seed pods and feed on the developing seeds causing them to turn brown and shrivel.
Begin monitoring canola when it bolts and continue until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.
Sample the crop for lygus bugs on a sunny day when the temperature is above 20°C and the crop canopy is dry. With a standard insect net (38 cm diameter), take ten 180° sweeps. Count the number of lygus bugs in the net.
Repeat the sampling in another 14 locations. Samples can be taken along or near the field margins. Calculate the cumulative total number of lygus bugs and then consult the sequential sampling chart (Figure C). If the total number is below the lower threshold line, no treatment is needed. If the total is below the upper threshold line, take more samples. If the total is on or above the upper threshold line, calculate the average number of lygus bugs per 10-sweep sample and consult the economic threshold table.
Sequential sampling for lygus bugs at late flowering stage in canola.
The economic threshold for lygus bugs in canola covers the end of the flowering (Table 1) and the early pod ripening stages (Table 2). Once the seeds have ripened to yellow or brown, the cost of controlling lygus bugs may exceed the damage they will cause prior to harvest, so insecticide application is not warranted.
Consider the estimated cost of spraying and expected return prior to making a decision to treat a crop. Remember that insecticide applications at bud stage in canola have not been proven to result in an economic benefit in production. The exception to this is in the Peace River region where early, dry springs and unusually high densities of lygus bug adults can occasionally occur at bud stage. In this situation, high numbers of lygus bugs feeding on moisture-stressed canola at bud stage is suspected to result in delay of flowering so producers in that region must monitor in fields that fail to flower as expected.
Table 1. Economic thresholds for lygus bugs in canola at late flowering and early pod stages (Wise and Lamb 1998).
1 Canola crop stage estimated using Harper and Berkenkamp 1975).
2 Economic thresholds are based on an assumed loss of 0.1235 bu/ac per lygus bug caught in 10 sweeps (Wise and Lamb. 1998. The Canadian Entomologist. 130: 825-836).
Table 2. Economic thresholds for lygus bugs in canola at pod stage (Wise and Lamb 1998).
3 Economic thresholds are based on an assumed loss of 0.0882 bu/ac per lygus bug caught in 10 sweeps (Wise and Lamb. 1998. The Canadian Entomologist. 130: 825-836).
Provincial Insect Pest Updates – The following provincial websites have their pest updates posted so click the links to access their reports:
● Alberta’s Insect Update (Call of the Land audio report of July 16, 2015)
Insect of the Week – Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide (2015) by Hugh Philip is a new publication from Agriculture and Agri-Food Canada. This growing season we will post an “Insect of the Week” in the form of short excerpts from the field guide. This week features several species of aphids (i.e., corn leaf, English grain, green peach, oat-birdcherry, pea, potato, soybean, turnip, greenbug).
Additionally, ladybird beetles were also featured in the Insect of the Week.
Crop Reports – The following provincial websites now have their Crop Reports posted so click the links to find their weekly updates:
West Nile Virus Risk – Reminder – Now is the time for DEET!The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. Areas yet to be highlighted in red on the map below will have accumulated sufficient heat for C. tarsalis to fly. As of July 12, 2015, the predicted development of C. tarsalis is most advanced in the southern areas of our prairie provinces with adults predicted to emerge from 350-400 DD in the map below ( will be highlighted in red).
The Public Health Agency of Canada posts information related to West Nile Virus in Canada and their website is located here. The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance. As of this week, one bird in New Brunswick and one bird in Ontario tested positive for West Nile-related deaths (click here to view the report).
Questions or problems accessing the contents of this Weekly Update? Please e-mail or call either Owen.Olfert@agr.gc.ca (tel. 306-385-9355) or Jennifer.Otani@agr.gc.ca (tel. 780-354-5132). Past and present “Weekly Updates” are very kindly posted to the Western Forum website by webmaster, Dr. Kelly Turkington. Please click here to link to that webpage.
Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide – The NEW Field Guide to Support Integrated Pest Management (IPM) in Field and Forage Crops is NOW available for download from www.publications.gc.ca. Two downloadable (~8 MB) versions of the complete field guide are available as either a ‘Regular’ (i.e., best for printing: English, French) or ‘Enhanced’ (i.e., best for viewing electronically with active internal and external hyperlinks: English-enhanced, French-enhanced).
Wind trajectories Related to Diamondback Moth (DBM) and Aster Leafhopper Introductions – Completed for the season. Please refer to earlier Weekly Updates for details related to backward and forward trajectories associated with air parcels moving over western Canadian locations.
Flea Beetles (Chrysomelidae: Phyllotreta species) – Helpful images produced by Dr. Julie Soroka (AAFC-Saskatoon) exemplifying percent of cotyledon leaf area consumed by flea beetles are posted at Canola Watch.
Cutworms (Noctuidae) – Cutworm biology, species information, plus monitoring recommendations are available at the Prairie Pest Monitoring Network’s Cutworm Monitoring Protocol. Also refer to these cutworm-specific fact sheets (Manitoba Agriculture and Rural Initiatives, Alberta Agriculture, Food and Rural Development). If cutworms are spotted in Albertan fields, please also consider using the Alberta Pest Surveillance Network’s “2015 Cutworm Reporting Tool” for online reporting located by clicking here. Data entered at that website uploads to a live “Cutworm Map”.
Canola Insect Scouting Chart – Reminder – The Canola Insect Scouting Chart has been updated with hyperlinks now directing growers to downloadable pages from the NEW Field Guide!
Alfalfa Weevil (Hypera postica) – Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon).
The map below is
the first of the predicted emergence maps for the wheat midge for
the 2015 growing season. Remember, wheat midge emergence and flight will also be affected by precipitation events and wind. Even so, if you are hoping
to catch the very first wheat midge as they start to emerge, keep watching the map below for areas
that will be highlighted below as lime-green (i.e., 600-693 DD).
Rain fell over
the past five days so watch for the updated map in the Weekly Update which
should be available by Thursday.
In 2014, the PPMN compiled data for the following sites highlighted in the map below. The monitoring data collected from these sites forms invaluable sources of information both now and into the future.
Agricultural people from federal, provincial, regional and industry sectors all contribute to this tremendous effort! Monitoring at sites like these below provides crucial information on insect pest risk before and during the growing season. Some sites are visited annually while others are checked weekly and all that data enables the synthesis and generation of risk and forecast maps like those posted here.
THANK YOU to all who contribute!
Please contact Dr. Owen Olfert at AAFC-Saskatoon for more information about this map.
