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.
Ladybird beetle larvae (Fig. 1), pupae (Fig. 2), and adults (Fig. 3) can all be found in fields at this time of year. Take a look at the various stages and the many patterns of native and introduced species to recognize these as Field Heroes! Ladybird beetles are categorized as general predators and will feed on several species of arthropods but are partial to aphids.
Figure 4. An aphid “mummy” adhered to a wheat awn. A “mummy” is the aphid host transformed to enclose a soon-to-emerge parasitoid wasp (photo credit: AAFC-Beaverlodge).
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.
Aphids can cause significant damage to fields and increase crop losses but low densities in a grain field sometimes have little economic impact on production. This is especially true if the aphid’s natural enemies (beneficial insects) are present in the field because they can keep the aphids under control.
The Cereal Aphid Manager is an easy-to-use mobile app that helps farmers and crop advisors control aphid populations in wheat, barley, oat or rye. It is based on Dr. Tyler Wist’s (AAFC-Saskatoon) Dynamic Action Threshold model. The model treats the grain field as an ecosystem and takes into account many complex biological interactions including:
the number of aphids observed and how quickly they reproduce
the number of different natural enemies of aphids in the field and how many aphids they eat or parasitize per day
the lifecycles of aphids and their enemies taking into account developmental stages, egg laying behaviour, population growth rate, lifespan, etc.
Frequent in-field scouting, supported by the app’s dynamic threshold, allows growers to weigh the above factors and the app predicts what the aphid population will be in seven days and the best time to apply insecticide based on economic thresholds.
Reminder This year, wet field conditions contributed to slug issues in cereals and canola. Researchers based at the University of Alberta are seeking live slug samples from field crops. Please take note of their collection protocol and help, if possible please! Watch for feeding channels on the upper surfaces of the flag leaf in wheat and plan to scout in the evening!
Figure 1. Deroceras reticulatum, the “grey field slug”, on wheat growing near Crooked Creek AB (August 2, 2018; det. Lien Luong).
Grey garden slugs were observed when field scouting was performed in the evening from 8:30-10:30pm in 2018 (Fig. 1 and 2). As the temperatures decreased, the slugs moved up the wheat stems, climbing to the topside of the flag leaf and onto the wheat heads although they did not appear to feed at the developing kernels. Wheat was hand-collected by clipping stems ~20cm above the ground and these samples later revealed a density of 1.04 slugs per stem (n=465 stems) causing the above damage (Fig. 2).
Figure 2. Flag leaf feeding damage on wheat caused by the grey field slug (Deroceras reticulatum). Photo taken near Crooked Creek AB on August 2, 2018, by J. Otani.
Specimens were forwarded to L. Luong (U of A) who identified the slugs from the above field as one species, Deroceras reticulatum, the grey field slug. The majority were juveniles. The grey field slug is the most common to occur in the home garden.
Thanks to Dr. John Gavloski (Manitoba Agriculture) who prepared the following in relation to slugs in field crops:
Slugs are a complicated problem because most general insecticides don’t work well on them.
Sluggo Professional (PCP#30025) is registered for slugs in field crops. It is a bait, which must be consumed by the slugs to be effective but it could be expensive on a large field.
Often insecticides don’t work well on slugs and it may be related to the mucous coating slugs exude.
Be wary, if an insecticide is applied, the product will likely not affect the slugs but it will kill the ground beetles and other natural enemies that prey upon or parasitize slugs and could exacerbate the slug problem.
Growers using no-till or minimum till operations may consider tillage to help reduce future levels of slugs.
Health Canada has an overview of snails relating to gardening posted here.
Reminder – Feeding channels on the upper surfaces of the flag leaf in wheat were reported and evening scouting revealed the culprit!
Figure 1. Deroceras reticulatum, the “grey field slug”, on wheat growing near Crooked Creek AB (August 2, 2018; det. Lien Luong).Figure 2. Flag leaf feeding damage on wheat caused by the grey field slug (Deroceras reticulatum). Photo taken near Crooked Creek AB on August 2, 2018, by J. Otani.
Field scouting was performed in the evening from 8:30-10:30pm. As the temperatures decreased, the slugs moved up the wheat stems, climbing to the topside of the flag leaf and onto the wheat heads although they did not appear to feed at the developing kernels. Wheat was hand-collected by clipping stems ~20cm above the ground to later reveal a density of 1.04 slugs per stem (n=465 stems) causing the above damage (Fig. 2).
Specimens were forwarded to L. Luong (U of A) who identified the slugs from the above field as one species, Deroceras reticulatum, the grey field slug. The majority were juveniles. The grey field slug is the most common to occur in the home garden.
Thanks to Dr. John Gavloski (Manitoba Agriculture) who prepared the following in relation to slugs in field crops:
Slugs are a complicated problem because most general insecticides don’t work well on them.
Sluggo Professional (PCP#30025) is registered for slugs in field crops. It is a bait, which must be consumed by the slugs to be effective but it could be expensive on a large field.
Often insecticides don’t work well on slugs and it may be related to the mucous coating slugs exude.
Be wary, if an insecticide is applied, the product will likely not affect the slugs but it will kill the ground beetles and other natural enemies that prey upon or parasitize slugs and could exacerbate the slug problem.
Growers using no-till or minimum till operations may consider tillage to help reduce future levels of slugs.
Health Canada has an overview of snails relating to gardening posted here.
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.
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 cereal leaf beetle versus Collops beetles:
Cereal leaf beetle, Boris Loboda
Cereal leaf beetles (Oulema melanopus), both adults and larva, feed on leaves (oat, barley, wheat, corn, etc), but it is the larval damage that can reduce yield and quality, especially if the flag leaf is stripped. Adults are 6-8 millimeters (.25-.31 inches) long with reddish legs and thorax (middle section between head and abdomen) and metallic bluish-black head and elytra (wing coverings).
Collops beetle, cc-by-nd-nc 1.0 Ashley Bradford
They may be confused with beneficial beetles belonging to the Collops genus (adults feed on aphids, stink bug eggs, moth eggs, small caterpillars, spider mites, whiteflies). Roughly the same size, they may have a red or orange thorax with/without red markings on their elytra, depending on the species. One consistent feature that will help distinguish between the two species is that the cereal leaf beetle elytra are smooth and shiny whereas the Collops’ elytra are covered in hairs.
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.
Reminder and Congratulations! The Cereal Aphid Management (CAM) Mobile Application Team was recognized with an Agriculture and Agri-Food Canada Gold Harvest Award this month! Team members included Ashraf Eid, Paul Faure, John Gavloski, François Jodoin, Elham Karimi, Eric Li, Jackson Macdonald, Nancy MacDonald, Owen Olfert, Chrystel Y. Olivier, Daniel Shen, Erl Svendsen, Gabriel Tobian, Tyler J. Wist.
“The app is a culmination of innovative thinking, extensive research, and most importantly collaboration in order to design a tool that met the needs of the farming community. The team’s ability to work together and build this application will result in economic savings, a greener environment, and increased crop quality in the food production industry.”
The Cereal Aphid Manager is an easy-to-use mobile app that helps farmers and crop advisors control aphid populations in wheat, barley, oat or rye. It is based on Dr. Tyler Wist’s (AAFC-Saskatoon) innovative Dynamic Action Threshold model. The model treats the grain field as an ecosystem and takes into account many complex biological interactions including:
the number of aphids observed and how quickly they reproduce
the number of different natural enemies of aphids in the field and how many aphids they eat or parasitize per day
the lifecycles of aphids and their enemies taking into account developmental stages, egg laying behaviour, population growth rate, lifespan, etc.
By taking into consideration factors like these, the app predicts what the aphid population will be in seven days and the best time to apply insecticide based on economic thresholds.
Note: Cereal aphids can blow up from the South at any time which cannot be predicted by the app. Therefore, farmers and crop advisors should regularly check fields during the growing season regardless of what Cereal Aphid Manager Mobile may recommend.
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).
Congratulations! The Cereal Aphid Management (CAM) Mobile Application Team was recognized with an Agriculture and Agri-Food Canada Gold Harvest Award this month! Team members included Ashraf Eid, Paul Faure, John Gavloski, François Jodoin, Elham Karimi, Eric Li, Jackson Macdonald, Nancy MacDonald, Owen Olfert, Chrystel Y. Olivier,
Daniel Shen, Erl Svendsen, Gabriel Tobian, Tyler J. Wist.
“The app is a culmination of innovative thinking, extensive research, and most importantly collaboration in order to design a tool that met the needs of the farming community. The team’s ability to work together and build this application will result in economic savings, a greener environment, and increased crop quality in the food production industry.”
The Cereal Aphid Manager is an easy-to-use mobile app that helps farmers and crop advisors control aphid populations in wheat, barley, oat or rye. It is based on Dr. Tyler Wist’s (AAFC-Saskatoon) innovative Dynamic Action Threshold model. The model treats the grain field as an ecosystem and takes into account many complex biological interactions including:
the number of aphids observed and how quickly they reproduce
the number of different natural enemies of aphids in the field and how many aphids they eat or parasitize per day
the lifecycles of aphids and their enemies taking into account developmental stages, egg laying behaviour, population growth rate, lifespan, etc.
By taking into consideration factors like these, the app predicts what the aphid population will be in seven days and the best time to apply insecticide based on economic thresholds.
Note: Cereal aphids can blow up from the South at any time which cannot be predicted by the app. Therefore, farmers and crop advisors should regularly check fields during the growing season regardless of what Cereal Aphid Manager Mobile may recommend.
Earlier this month, feeding channels on the upper surfaces of the flag leaf in wheat were reported and evening scouting revealed this culprit!
Figure 1. Deroceras reticulatum, the “grey field slug”, on wheat growing near Crooked Creek AB (August 2, 2018; det. Lien Luong).Figure 2. Flag leaf feeding damage on wheat caused by the grey field slug (Deroceras reticulatum). Photo taken near Crooked Creek AB on August 2, 2018, by J. Otani.
Field scouting was performed in the evening from 8:30-10:30pm. As the temperatures decreased, the slugs moved up the wheat stems, climbing to the topside of the flag leaf and onto the wheat heads although they did not appear to feed at the developing kernels. Wheat was hand-collected by clipping stems ~20cm above the ground to later reveal a density of 1.04 slugs per stem (n=465 stems) causing the above damage (Fig. 2).
Specimens were forwarded to L. Luong (U of A) who identified the slugs from the above field as one species, Deroceras reticulatum, the grey field slug. The majority were juveniles. The grey field slug is the most common to occur in the home garden.
Thanks to Dr. John Gavloski (Manitoba Agriculture) who prepared the following in relation to slugs in field crops:
Slugs are a complicated problem because most general insecticides don’t work well on them.
Sluggo Professional (PCP#30025) is registered for slugs in field crops. It is a bait, which must be consumed by the slugs to be effective but it could be expensive on a large field.
Often insecticides don’t work well on slugs and it may be related to the mucous coating slugs exude.
Be wary, if an insecticide is applied, the product will likely not affect the slugs but it will kill the ground beetles and other natural enemies that prey upon or parasitize slugs and could exacerbate the slug problem.
Growers using no-till or minimum till operations may consider tillage to help reduce future levels of slugs.
Health Canada has an overview of snails relating to gardening posted here.
Reminder – While scouting, you may encounter these fascinating organisms…..
Figure 1. Ladybird beetle larva (photo credit: AAFC-Beaverlodge)Figure 2. Ladybird beetle pupa (Left) and larva (Right) (photo credit: AAFC-Beaverlodge)Figure 3. Ladybird beetle pupa (photo credit: AAFC-Beaverlodge)Figure 4. Ladybird beetle (Coccinella septempunctata) (photo credit: AAFC-Beaverlodge)Figure 5. Aphids nestled on wheat head (photo credit: AAFC-Beaverlodge)Figure 6. An aphid “mummy” adhered to a wheat awn. Mummy is the aphid host converted to enclose a soon-to-emerge parasitoid wasp (photo credit: AAFC-Beaverlodge)
Ladybird beetle larvae (Fig. 1-2), pupae (Fig. 2-3), and adults (Fig. 4) can all be found in fields at this time of year. Take a look at the various stages and the many patterns of native and introduced species to recognize these as Field Heroes! Ladybird beetles are categorized as general predators and will feed on several species of arthropods but are partial to aphids (Fig. 5).
The English grain aphid (Sitobion avenae) has started to appear across the Prairies in various cereal crops this past week so the time to scout is now. Look for this aphid infesting wheat heads (favourite host) as well as barley, oat, rye, Timothy and canaryseed.
This aphid can also be a vector for barley yellow dwarf virus. You might see the green, red colour morph or both morphs in fields this year (Fig. 1). You will probably also see ladybeetle (@FieldHeroes) adults and larvae hunting the aphids (Fig. 2). The economic threshold for aphids in spring wheat in Western Canada is 12-15 aphids per head prior to the soft dough stage.
Agriculture and Agri-Food Canada, with funding from the Pest Management Centre, has developed a smartphone app called Cereal Aphid Manager (CAM) to facilitate scouting for aphids in cereals that also allows you to record the beneficial insects in the field that can keep aphid populations below the economic threshold – available at Apple iTunes and Google Play app stores. CAM information and download links.
For more information on the English grain aphid, check out our Insect of the Week page!
Submitted by Dr. Tyler Wist (Tyler.Wist@agr.gc.ca).
Fig. 1 Green and red morph English grain aphid (Tyler Wist, AAFC)Fig. 2 Seven-spotted lady bird larva hunting aphids (Tyler Wist, AAFC)
This week’s Insect of the Week is the wheat stem sawfly (Cephus cinctus). Adults are 8-13mm long and have a shiny, black, wasp-like body and yellow legs. When at rest on plant stems, they point their heads downwards.
Mature larvae overwinter in the base of stems in infested fields. In June, females emerge and fly to nearby wheat crops, where they can lay up to 50 eggs each on stems.
The wheat stem sawfly feeds primarily on spring and durum wheat, though winter wheat, rye, grain corn, barley, and some native grasses can support sawfly development. It cannot develop on oats.
Larvae feed on the pith of host plants stems which can cause a reduction in crop yield and quality. When plants mature, larvae move to the bottom of the stem to overwinter.
For more information about the wheat stem sawfly, head over to our Insect of the Week page!
While scouting, you may encounter these fascinating organisms…..
Figure 1. Ladybird beetle larva (photo credit: AAFC-Beaverlodge)Figure 2. Ladybird beetle pupa (Left) and larva (Right) (photo credit: AAFC-Beaverlodge)Figure 3. Ladybird beetle pupa (photo credit: AAFC-Beaverlodge)Figure 4. Ladybird beetle (Coccinella septempunctata) (photo credit: AAFC-Beaverlodge)Figure 5. Aphids nestled on wheat head (photo credit: AAFC-Beaverlodge)Figure 6. An aphid “mummy” adhered to a wheat awn. Mummy is the aphid host converted to enclose a soon-to-emerge parasitoid wasp (photo credit: AAFC-Beaverlodge)
Ladybird beetle larvae (Fig. 1-2), pupae (Fig. 2-3), and adults (Fig. 4) can all be found in fields at this time of year. Take a look at the various stages and the many patterns of native and introduced species to recognize these as Field Heroes! Ladybird beetles are categorized as general predators and will feed on several species of arthropods but are partial to aphids (Fig. 5).
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.
Reminder – Aphids can cause significant damage to fields and increase crop losses, but just because aphids are present in a grain field doesn’t mean they will have a negative economic impact on production. This is especially true if there are aphid’s natural enemies (beneficial insects) in the field to keep them under control.
The Cereal Aphid Manager is an easy-to-use mobile app that helps farmers and crop advisors control aphid populations in wheat, barley, oat or rye. It is based on Dr. Tyler Wist’s (AAFC-Saskatoon) innovative Dynamic Action Threshold model. The model treats the grain field as an ecosystem and takes into account many complex biological interactions including:
the number of aphids observed and how quickly they reproduce
the number of different natural enemies of aphids in the field and how many aphids they eat or parasitize per day
the lifecycles of aphids and their enemies taking into account developmental stages, egg laying behaviour, population growth rate, lifespan, etc.
By taking into consideration factors like these, the app predicts what the aphid population will be in seven days and the best time to apply insecticide based on economic thresholds.
Note: Cereal aphids can blow up from the South at any time which cannot be predicted by the app. Therefore, farmers and crop advisors should regularly check fields during the growing season regardless of what Cereal Aphid Manager Mobile may recommend.
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.
The insect of the week is the Bruner grasshopper (Melanoplus bruneri). Observed since the 1920s in Canada, this species is a relatively recent addition to the list of grasshopper pest species occurring in crop production areas. Previously, it was not considered a crop pest.
It is a medium-sized grasshopper (males 18-22 mm; females 22-27 mm) with dark and often reddish colour tones. It is similar in appearance and size to the migratory grasshopper (Melanoplus sanguinipes) but is distinguished by differences in the male genitalia. The Bruner grasshopper has recently become the predominant grasshopper species in many northern crop production areas of Alberta and parts of Saskatchewan. It occupies a wide geographic range and is found throughout much of Canada and the United States.
The Bruner grasshopper feeds mainly on broadleaf host plants but the species can feed upon several species of grasses. It has been observed in high numbers feeding in pulse crops, canola, and cereals.
Researchers are investigating if this species follows a two-year life cycle (i.e. do eggs require exposure to two winters before hatching?) in the Peace River region and parts of central Alberta.
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.
Reminder – Researchers need your help – They are looking for LIVE cereal leaf beetle larvae from any field across the Canadian prairies in order to assess Tetrastichus julis parasitism rates.
If larvae are encountered in 2018, please carefully collect 20-30 of them and put them with some cereal leaves and a moist paper towel in a hard container (e.g. plastic yogurt container) with holes poked in the lid for air. Pack the parcel with ice packs, label with your name, date, crop type, and location, and send them to us. Email or phone us for information on how to ship for free.
What’s in it for you? Learn if cereal leaf beetle is being controlled by natural enemies in your field. If you need T. julis, we may be able provide you with some.
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.
Researchers need your help – They are looking for LIVE cereal leaf beetle larvae from any field across the Canadian prairies in order to assess Tetrastichus julis parasitism rates.
If larvae are encountered in 2018, please carefully collect 20-30 of them and put them with some cereal leaves and a moist paper towel in a hard container (e.g. plastic yogurt container) with holes poked in the lid for air. Pack the parcel with ice packs, label with your name, date, crop type, and location, and send them to us. Email or phone us for information on how to ship for free.
What’s in it for you? Learn if cereal leaf beetle is being controlled by natural enemies in your field. If you need T. julis, we may be able provide you with some.
Reminder – Last week turned out to be our wireworm blitz! This complicated group of insect species was featured in the Insect of the Week AND we include the survey results again this week!
The following maps summarize the main results of a survey of pest species of wireworms of the Canadian Prairie Provinces. Samples (both larvae and beetles) were submitted to Dr. Bob Vernon’s lab in Agassiz, BC, from 2004 to 2017, and identified by Dr. Wim van Herk (Fig. 1). Species identifications were confirmed with barcoding.
Figure 1. Sampling locations for click beetles and wireworm larvae (Coleoptera: Elateridae) submitted for wireworm surveying from 2004-2017.
Approximately 600 samples were submitted, with the number of larvae per sample typically less than five (Fig. 1). More samples are welcome, particularly from areas currently not well represented on the maps.Please provide either the legal land description or latitude and longitude coordinates with a sample. Any information on the cropping history or whether fields were irrigated is helpful.
Review the complete survey summary posted in Week 05 (for Jun 7, 2018).
Disclaimer: Please do not distribute or use the contents of this post, including any maps, without obtaining prior permission.
Obtain further information or arrange shipment of wireworm or click beetle samples by contacting: Dr. Wim van Herk Agriculture and Agri-Food Canada Agassiz Research and Development Centre 6947 Highway 7, Agassiz, BC, V0M 1A0 wim.vanherk@agr.gc.ca
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.
This week’s Insect of the Week is a frustrating pest of many crops: wireworm. Wireworms are the soil-dwelling larval stage of the click beetles (Elateridae). There are hundreds of click beetle species in the prairies, but the term wireworm refers to those that are pests, which in Canada is approximately 20 species. With the loss of effective insecticides (e.g. lindane), wireworms have re-emerged in recent years as primary pests of potato, cereals, and vegetables. On the prairies, we have 3 predominant pest species (Selatosomus destructor, Limonius californicus, and Hypnoidus bicolor; see photo), and their larvae vary (among other things) in life history (2-7 years), color (white to orange), cuticle thickness, distribution, behaviour, and susceptibility to insecticides.
Wireworms are patchy in distribution, difficult to monitor, and difficult to kill. We have a lot to learn about these resilient pests. Since the mid-1990’s AAFC has had a national research team (Bob Vernon et al.) screening for effective insecticides and developing trapping and monitoring methods, cultural controls (e.g., crop rotation), and biocontrols to manage the adult and larval forms of these pests.
For more information about wireworms, check out our Insect of the Week page!
The three most troublesome wireworm species on the prairies in their adult and larval stages. Note the different sizes and colours. From left to right, S. destructor, L. californicus, H. bicolor. Photo by David Shack, AAFC-Lethbridge.
The following maps summarize the main results of a survey of pest species of wireworms of the Canadian Prairie Provinces. Samples (both larvae and beetles) were submitted to Dr. Bob Vernon’s lab in Agassiz, BC, from 2004 to 2017, and identified by Dr. Wim van Herk (Fig. 1). Species identifications were confirmed with barcoding.
Figure 1. Sampling locations for click beetles and wireworm larvae (Coleoptera: Elateridae) submitted for wireworm surveying from 2004-2017.
Approximately 600 samples were submitted, with the number of larvae per sample typically less than five (Fig. 1). More samples are welcome, particularly from areas currently not well represented on the maps.Please provide either the legal land description or latitude and longitude coordinates with a sample. Any information on the cropping history or whether fields were irrigated is helpful.
The main findings of this survey are that: 1. Wireworms are re-emerging as primary pests of cereals and other crops, particularly in southern Alberta and Saskatchewan. This can be attributed to several factors, including changes in seeding and cultivation resulting in higher soil moisture and increased food availability, and therefore greater wireworm survival; the elimination of effective insecticides such as lindane and the decline of organochlorine residues in the soil; and the present lack of insecticides that actually kill wireworms.
2. Limonius californicus is generally the predominant pest species in fields reporting heavy wireworm damage, occasionally building up to very high populations and resulting in complete crop wrecks (Fig. 2). This was not the case when Glen et al. (1943) or Doane (1977) conducted their surveys; L. californicus was considered a minor species at those times. Selatosomus destructor (Fig. 3) and Hypnoidus bicolor (Fig. 4) are still the most common species. The pest status of another commonly found species, the predaceous Aeolus mellillus (Fig. 5), is unclear. The following species listed by Glen et al. (1943) as pests of agriculture in the Prairie Provinces were found also, but infrequently: Agriotes mancus, A. criddlei, A. stabilis, Hemicrepidius memnonius, L. pectoralis, and various Dalopius sp.
Figure 2. Distribution of Limonius californicus (Coleoptera: Elateridae) submitted for wireworm surveying from 2004-2017.Figure 3. Distribution of Selatosomus destructor (Coleoptera: Elateridae) submitted for wireworm surveying from 2004-2017.Figure 4. Distribution of Hypniodes bicolor (Coleoptera: Elateridae) submitted for wireworm surveying from 2004-2017.Figure 5. Distribution of Aeolus mellillus (Coleoptera: Elateridae) submitted for wireworm surveying from 2004-2017.
3. Multiple pest species are frequently found in the same fields where damage is reported (i.e. about 25% of the time, despite the small number of larvae per sample). This is particularly important as pest species can vary considerably in the type of damage they cause (e.g. it remains unclear if H. bicolor is damaging to potato), their life history (e.g. duration of the larval stage), and susceptibility to insecticides.
Acknowledgements: These maps are only possible thanks to the collections done by a large team of local entomologists and agrologists. We are extremely grateful to them; thank you to everyone who participated! A special thank you to Ted Labun and colleagues at Syngenta Crop Protection (Canada), and to Bayer CropScience, for providing the bulk of the samples.
Disclaimer: Please do not distribute or use the contents of this post, including any maps, without obtaining prior permission.
Obtain further information or arrange shipment of wireworm or click beetle samples by contacting: Dr. Wim van Herk Agriculture and Agri-Food Canada Agassiz Research and Development Centre 6947 Highway 7, Agassiz, BC, V0M 1A0 wim.vanherk@agr.gc.ca
Further wireworm reading: Burrage RH (1964) Trends in damage by wireworms (Coleoptera: Elateridae) in grain crops in Saskatchewan, 1954–1961. Canadian Journal of Plant Science, 44: 515–519. https://doi.org/10.4141/cjps64-102
Doane JF (1977) Spatial pattern and density of Ctenicera destructor and Hypolithus bicolor (Coleoptera: Elateridae) in soil in spring wheat. The Canadian Entomologist 109: 807–822. https://doi.org/10.4039/Ent109807-6
Doane JF (1977) The flat wireworm, Aeolus mellillus: studies on seasonal occurrence of adults and incidence of the larvae in the wireworm complex attacking wheat in Saskatchewan. Environmental Entomology 6: 818–822. https://doi.org/10.1093/ee/6.6.818
Glen R, King KM, Arnason AP (1943) The identification of wireworms of economic importance in Canada. Canadian Journal of Research 21: 358-387. https://doi.org/10.1139/cjr43d-030
van Herk WG, Vernon RS (2014) Click beetles and wireworms (Coleoptera: Elateridae) of Alberta, Saskatchewan, and Manitoba. In: Arthropods of Canadian Grasslands (Volume 4): Biodiversity and Systematics Part 2. (Edited by D.J. Giberson and H.A. Carcamo). Biological Survey of Canada, pp. 87-117. https://biologicalsurvey.ca/monographs/read/17
Zacharuk RY (1962) Distribution, habits, and development of Ctenicera destructor (Brown) in western Canada, with notes on the related species C. aeripennis (Kby.) (Coleoptera: Elateridae). Canadian Journal of Zoology 40: 539–552. https://doi.org/10.1139/z62-046
It’s spring, so it’s cutworm season. This week’s insect is the darksided cutworm. Mature larvae are hairless, greyish with a prominent white stripe on either side just above their legs. It is a climbing cutworm with feeding occurring at night. They have a broad host range including cereals, canola, corn, flax, sunflower, vegetables berry and tree fruits.
Find out more about the darksided cutworm at the Insect of the Week page. Other important species include dingy, army, redbacked and pale western cutworms (See Insect of the Week: 2017 – May 1, 8, 15 and 29).
Darksided cutworm
Photocredit John Gavloski, Manitoba Ministry of Agriculture
In addition, Cutworm Pests of Crops on the Canadian Prairies – Identification and Management Field Guide was recently published (2017). This new handy manual has chapters on general biology, history of outbreaks, scouting techniques, natural enemies and general control options. The meat of the manual is descriptions of 24 cutworm species, their lifecycle, hosts, damage, monitoring and economic thresholds. To download a copy, go to the Cutworm Field Guide page.
Aphids can cause significant damage to fields and increase crop losses, but just because aphids are present in a grain field doesn’t mean they will have a negative economic impact on production. This is especially true if there are aphid’s natural enemies (beneficial insects) in the field to keep them under control.
The Cereal Aphid Manager is an easy-to-use mobile app that helps farmers and crop advisors control aphid populations in wheat, barley, oat or rye. It is based on Dr. Tyler Wist’s (Agriculture and Agri-Food Canada Field Crop Entomologist) innovative Dynamic Action Threshold model. The model treats the grain field as an ecosystem and takes into account many complex biological interactions including:
the number of aphids observed and how quickly they reproduce
the number of different natural enemies of aphids in the field and how many aphids they eat or parasitize per day
the lifecycles of aphids and their enemies taking into account developmental stages, egg laying behaviour, population growth rate, lifespan, etc.
By taking into consideration factors like these, the app predicts what the aphid population will be in seven days and the best time to apply insecticide based on economic thresholds.
Note: Cereal aphids can blow up from the South at any time which cannot be predicted by the app. Therefore, farmers and crop advisors should regularly check fields during the growing season regardless of what Cereal Aphid Manager Mobile may recommend.
This week’s insect is the glassy cutworm. The larva is greyish-white, semi-translucent and shiny (i.e. glass-like) with a orange-brown head. Since it overwinters as a larva, it is active as soon as the ground thaws. It feeds underground and rarely come to the surface. Their main host crop are grasses but will also attack wheat and corn. Corn planted following wheat may be particularly at risk.
Other important species include dingy, army, redbacked and pale western cutworms (See Insect of the Week: 2017 – May 1, 8, 15 and 29).
In addition, Cutworm Pests of Crops on the Canadian Prairies – Identification and Management Field Guide was just published (2017). This new handy field guide has chapters on general biology, history of outbreaks, scouting techniques, natural enemies and general control options. The guide includes descriptions of 24 cutworm species, their lifecycle, hosts, damage, monitoring and economic thresholds. To download a copy, go to the Cutworm Field Guide page.
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.
This week’s Insect of the Week is the brown marmorated stink bug (Halyomorpha halys). Stink bugs get their name from the foul odour they release when threatened. Nymphs and adults prefer field corn and soybean, but infestations have been reported on rape, pea, sunflower and cereals in the USA. They have also been known to attack tree fruits, berries, vegetables and many ornamental trees and shrubs. They are not known to be established in the Prairies, but have been found in the BC Southern Interior, Ontario and Quebec. Feeding causes damage to seeds and seed pods, reducing yield.
Brown marmorated stink bug – adult (CC-BY 2.0 Katja Schulz)
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.
The Wheat Stem Maggot, Meromyza americana (Diptera) isa minorpest that causes eye-catching damage in wheat, rye, barley, oat, millet, timothy, brome, crested wheatgrass and bluegrass. This is a timely insect of the week, because the larval damage (dead white heads in an otherwise green field) started to appear in the last few weeks and is now highly visible in many fields.
Your eyes are naturally drawn to these white heads and can cause you to overestimate the actual amount of damage to your fields. However, the damage is usually limited to 1-5% of the crop. To identify if the wheat stem maggot is the culprit, gently pull on the white head to see if it easily separates from the flag leaf sheath and shows evidence of feeding damage at the base of the culm.
By the time you see damage, the greenish-white larva has exited and is off to begin a second generation that will overwinter in volunteer cereals. There are no registered chemicals or resistant varieties so your best management practices are rotate to non-cereals/non-grassses, destroy infested stubble, and control volunteer hosts and grassy weeds. Delayed seeding, where/when possible may also limit damage.
For more information on the Wheat Stem Maggot, see our Insect of the Week page.
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.
This week’s Insect of the Week is the cereal leaf beetle. Wheat is their preferred host, but they also feed on oats, barley, corn, rye, triticale, reed canarygrass, ryegrass, fescue, wild oats, millet and other grasses. Adults and larvae feed on the leaf tissue of host plants. Yield quality and quantity is decreased if the flag leaf is stripped. It is also interesting to note that larvae carry all of their own fecal waste with them as protection from predators.
For more information on the cereal leaf beetle, see our Insect of the Week page.
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 the group of aphids known
as cereal aphids. These aphids include the corn leaf aphid, the English grain
aphid, the oat-birdcherry aphid and the Russian wheat aphid. They feed on
cereal crops and are vectors of viruses, causing lower crop quality and yield. There are several natural enemies of cereal aphids, including various species of wasps and beetles.
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!
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.
Recall the following (posted May 25, 2016) – Predicted dates of peak emergence of CLB eggs and larvae:
Lifecycle and Damage: Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 1). 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 shelter belts, deciduous and conifer forests. They emerge in the spring once temperature reaches 10-15 ºC and are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals.
Figure 1. Adult Oulema melanopus (~4.4-5.5 mm long).
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 (Fig. 2). When the larva completes its growth, it drops to the ground and pupates in the soil.
Figure 2. Larval stage of Oulema melanopus with characteristic feeding damage visible on leaf.
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.
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 that are 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 that are close to 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.
● Because the CLB larvae are covered in a sticky secretion, they are often covered in debris and are very difficult to see within a sweep-net sample.
● 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 (Fig. 2), leaving only a thin membrane. When damage is extensive, leaves turn whitish.
Fact sheets for CLB are published by the province of Alberta and available from the Prairie Pest Monitoring Network. Also access the Oulema melanopus page from the new “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide”.
Tetrastichus julis (parasitoid) Last year, the focus of the Insect of the Week was crop pests. This year, we’re changing things up and highlighting the many natural enemies that help you out, silently and efficiently killing off crop pests. [note: featured Insects of the Week in 2015 are available on the Insect of the Week page] This week’s Insect of the Week is Tetrastichus julis (sorry, no common name), an important cereal leaf beetle parasitoid. Where T. julis has become established, it can reduce cereal leaf beetle populations by 40 – 90%, preventing yield loss without using pesticides. See also the factsheet, BiologicalControl at its Best, Using theT. julis Wasp toControl the Cereal Leaf Beetle (French version).
For information about the cereal leaf beetle (p. 24) and other pests and their natural enemies, see the new Field Crop and Forage Pests and their Natural Enemies in Western Canada – Identification and Management Field Guide for identification, life cycle and conservation options (download links for field guide available on the Insect of the Week page).
T. julis adult parasitizing a cereal leaf beetle larva
Cereal leaf beetle (Oulema melanopus) – The following are results from the bioclimate model which predicts cereal leaf beetle (CLB) populations.
As of May 23, 2016, the CLB model indicated that oviposition is well underway:
In Alberta and western Saskatchewan, development was similar to the previous week.
Warmer conditions in eastern Saskatchewan and Manitoba resulted in faster development.
Larval populations are predicted to peak in mid-June across most locations in the southern prairies.
Predicted dates of peak emergence of CLB eggs and larvae:
The following model outputs have been updated this week and reflect the predicted stages of CLB present in fields in relation to its parasitoid, Tetrastichus julis.
Fact sheets for CLB are published by the province of Alberta and available from the Prairie Pest Monitoring Network. Also access the Oulema melanopus page from the new “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide”.
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.
