The first adult wheat midge of 2023 were reported in Saskatchewan last week. This year could be an interesting year for wheat midge. Some areas have had sufficient rain to trigger the end of diapause and the completion of larval and pupal development. If adult emergence coincides with susceptible crop stages, damage could result. Scouting for wheat midge right now is very important!
This is a busy week for our field research programs across western Canada. In particular, the annual cabbage seedpod weevil survey has begun. For farmers in Alberta, watch the map for near-real-time monitoring results from the cabbage seedpod weevil survey! It looks like some fields in southern Alberta have high numbers of cabbage seedpod weevils. The PPMN monitoring protocol for cabbage seedpod weevil is available on the Monitoring Protocol page.
Because we are so busy in the field, this Weekly Update is shorter than usual. We decided to focus on wheat midge due to adult emergence reported last week, but do not forget about grasshoppers, diamondback moths, or bertha armyworm. This Weekly Update includes a short post with important links for all three of these species.
This week, the Insect of the Week also featured the wheat midge, a pest of cereal crops. In the next two weeks, we will feature the parasitoid of cereal leaf beetle and natural enemies of wheat midge.
Remember, insect Monitoring Protocols containing information about in-field scouting as well as information about insect pest biology and identification.
Questions or problems accessing the contents of this Weekly Update? Please contact Dr. Meghan Vankosky (meghan.vankosky@agr.gc.ca) to get connected to our information. Past Weekly Updates, full of information and helpful links, can be accessed on our Weekly Update page.
During the week of June 19-25, the prairie average daily temperature was 1°C warmer than normal (Fig. 1). The warmest temperatures were observed across Manitoba, with Dauphin, Manitoba recording temperatures 4.5°C warmer than normal. The coolest temperatures occurred across eastern Alberta. Calgary, Alberta, for example was 2°C cooler than normal.
Figure 1. Seven-day average temperature (°C) observed across the Canadian prairies for the period of June 19-25, 2023.
Average temperatures over the past 30 days (May 27 to June 25, 2023) have been 3.5°C above normal with the warmest values being reported across Manitoba and Saskatchewan (Fig. 2). Relative to climate normals, Dauphin, Manitoba was 5.5°C warmer than normal. In the last 30 days, temperatures have been coolest in the Peace River region; Grande Prairie, Alberta was only 1°C warmer than normal.
Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of May 27 to June 25, 2023.
Seven-day cumulative rainfall was greatest in a region around Edmonton, Alberta (Fig. 3). Precipitation amounts were minimal for southern Alberta and a large area of Saskatchewan.
Figure 3. Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 19 – 25, 2023.
The greatest 30 day rainfall totals (100-160mm) were reported from a region near Edmonton, Alberta (Fig. 4); rainfall totals in some of those areas have been 200% of normal. Rainfall amounts continue to be low across the southern prairies and near Saskatoon, Saskatchewan. For example, at Carman, Manitoba rainfall has been only 26% of normal and Brooks, Alberta has received only 49% of the precipitation expected in an average year.
Figure 4. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 27 to June 25, 2023.
Wheat midge (Sitodiplosis mosellana) development is ahead of normal. Last week, wheat midge pupae were just beginning to appear at the soil surface. This week, where wheat midge populations are present, pupae should be the most abundant life-stage (Fig. 1). Recent rainfall in the Peace River region and Edmonton regions may have resulted movement of larvae to the soil surface and subsequent occurrence of pupae. First emergence of adults was reported last week.
Figure 1. Percent of wheat midge (Sitodiplosis mosellana) that is predicted to be in the pupal stage in western Canada, as of June 25, 2023.
Model simulations indicate that adults may be occurring in fields near Saskatoon, Regina, Estevan and Melita (Fig. 2). It is expected that adult populations may peak later next week. Oviposition is predicted to begin over the next few days.
Figure 2. Percent of wheat midge (Sitodiplosis mosellana) that is predicted to be in the adult stage in western Canada, as of June 25, 2023.
Based on the occurrence of wheat midge adults, field monitoring should begin now. In order to assess wheat midge populations and to take the appropriate action, it is recommended that fields should be monitored when wheat is between heading and flowering. Field inspection should be carried out after 8:30 p.m. when the female midge are most active. Females are more active when the temperature is above 15°C and wind speed is less than 10 km/h. Wheat midge populations can be estimated by counting the number of adults present on four or five wheat heads.
Development of the pest grasshoppers continues to be ahead of schedule in 2023, as compared to past years. The first adult two-striped grasshoppers (Melonplus bivittatus) were collected on June 15 (Alberta) and June 19-20 (Saskatchewan). No one that we’ve spoken to remembers finding adult two-striped grasshoppers in June before. Especially in the south, densities are quite high and crop damage is being reported, as well as spraying to protect crops.
Model simulations for grasshopper development indicate that grasshoppers should range from first to fifth instars with some adults now present at many locations across the prairies, as of June 25. Based on average instar, development is most advanced across the southern prairies where 65% of the population is predicted to be fourth and 5th instar, with some adults also present (Fig. 1). In an ‘average year’, the majority of the grasshopper population (60%) would typically be in the first, second, and third instars in late June.
Figure 1. Predicted grasshopper (Melanoplus sanguinipes) development, presented as average instar, across the Canadian prairies as of June 25, 2023.
Based on occurrence of fifth instar grasshoppers, development is most advanced across southern Manitoba (Fig. 2).
Figure 2. Predicted migratory grasshopper (Melanoplus sanguinipes) development, presented as the percent of the population in the fifth instar, across the Canadian prairies as of June 25, 2023.
Adult two-striped grasshoppers (Melanoplus bivittatus) and migratory grasshoppers (M. sanguinipes) have been observed across the southern prairies.
Last week, models predicted that first instar bertha armyworm larvae might be present in some areas of the prairies. Bertha armyworm larvae could also be developing quickly, thanks to warm weather. The network of pheromone traps across the prairies is reporting low numbers of adults (less than 300 cumulative catch), including in Manitoba (check out the June 21 Manitoba Crop Pest Update) and Alberta. Risk to yield from bertha armyworm increases when cumulative trap catches exceed 300 (300-900 = medium risk, >900 = high risk). For information about scouting, check out the PPMN protocol and the Alberta Agriculture and Irrigation pages.
Diamondback moth
Some areas of the prairies might be at risk of damage from diamondback moth; pheromone traps with cumulative counts greater than 25 male moths so far in 2023 are located around Rosetown and Swift Current in Saskatchewan, in the Vulcan area in Alberta, and in the Central, Eastern, and Interlake regions in Manitoba (see the June 21 Manitoba Crop Pest Update). Like grasshoppers and bertha armyworm, diamond back moth development occurs quickly in warm weather. Last week, we predicted that diamondback moths had reached the second non-migrant generation and we heard of some sightings of larvae in some areas of the prairies. Because diamondback moth can have multiple generations in a single growing season, their populations can build up quickly. Keep scouting for diamondback moth to avoid unpleasant surprises later this summer.
To scout for diamondback moth, estimate the number of diamondback moth larvae per m2 at several locations in a field. The economic threshold for diamondback moth is NOT based on pheromone traps or sweep net samples, but on the density of larvae per plant. For immature and flowering canola, the economic threshold is 100-150 larvae/m2. In podded canola, the economic threshold is 200-300 larvae/m2. See the Field Crop and Forage Pests guide and monitoring protocol for more information about scouting for diamondback moth.
Developing tools for the management of Lygus bugs in faba bean
*The text of this post was written by Teresa Aguiar-Cordero and Sean Prager.
This research project, led by Sean Prager and Teresa Aguiar-Cordero, focuses on studying insects in the genus Lygus and their impact on faba bean crops in the province of Saskatchewan. Faba beans are a significant legume crop in the region, but they face threats from various insect pests, including Lygus species. Lygus bugs feed on faba beans by injecting salivary enzymes into the plant, resulting in damage such as hull perforations, seed coat discoloration, and tissue wilting which reduces yield. Damage to seed lowers the quality and grade of faba beans below that for human consumption with substantial economic consequences.
Microscope image of an adult Lygus bug. Picture provided by Teresa Aguiar-Cordero, University of Saskatchewan.
The project aims to address crucial knowledge gaps regarding Lygus bugs in faba beans. By conducting a survey across Saskatchewan, the study aims to determine the optimal timing and methods for effective Lygus sampling. In addition to the survey, a series of no-choice bioassay are currently being performed to quantify the relationship between Lygus bug numbers and the resulting damage to faba bean pods, which can help develop action thresholds.
Faba bean pods with damage resulting from Lygus bug feeding activity. Picture provided by Teresa Aguiar-Cordero, University of Saskatchewan.
As part of the future directions, the researchers plan to incorporate the electrical penetration graph technique (EPG) to gain a better understanding of the feeding behavior of Lygus bugs in faba beans. This technique will provide valuable insights into the precise feeding patterns employed by Lygus bugs.
In addition, a series of choice bioassays will be conducted to analyze and determine the preferences of Lygus when given a choice of different crop and plant species. This will help establish which crops Lygus may migrate into faba bean from. By studying the preferences of Lygus bugs for different crops, the researchers aim to identify potential trap crops that can attract Lygus populations as part of a management program to reduce the impact of Lygus bugs on faba bean crops.
The project’s outcomes will contribute important information and management tools for growers, enabling them to mitigate the impact of Lygus insects on faba bean crops. By understanding the associations between Lygus numbers and damage, and exploring innovative strategies such as trap crops, the project strives to minimize damage and decrease losses for growers.
Teresa Aguiar-Cordero is a graduate student at the University of Saskatchewan, working with Dr. Sean Prager to study Lygus bugs.
Visit the Alberta Insect Pest Monitoring Network and Crop Insects pages for information about insects and monitoring in Alberta, including links for live maps from the 2023 monitoring season for diamondback moth, bertha armyworm, cutworms, and cabbage seedpod weevil (new last week!).
New issues of the Saskatchewan Crop Production News are coming soon in 2023. Use the link to browse the articles from 2022 or subscribe to receive new issues of the newsletter as they are published online.
Weekly Manitoba Crop Pest Updates for 2023 are available online with timely updates about insect pests, weeds, and plant pathogens. Watch their website for new Crop Pest Updates (usually published on Wednesdays this year).
Now is the time to get out and scout for wheat midge!
Wheat midge are small, orange, fragile-looking flies that attack members of the grass family including barley, couch grass, wheat grass, triticale, and spring rye, though their preferred host is wheat.
Adult wheat midge. Picture credit: Shelby Dufton and Amanda Jorgensen, both of AAFC-Beaverlodge.
Adults emerge from mid-June through mid-July and typically coincide with wheat head development and flowering. Wheat midge remain in the humid crop canopy throughout the day and emerge on calm, warm evenings to mate and lay eggs. Eggs are laid singly or in groups of three to five on wheat kernels prior to flowering.
Adult wheat midge. Picture credit: Shelby Dufton and Amanda Jorgensen, both of AAFC-Beaverlodge.
Upon hatching, larvae crawl to developing kernels and feed for two to three weeks. Larval feeding damage results in shriveled, misshapen, cracked, or distorted kernels. Kernels must be inspected within the glume, as damage may not be readily apparent at a glance. Lost or damaged kernels from feeding result in lower crop yield and quality. The Canadian Grain Commission allows midge damage between two and five percent prior to impacting the assigned grade.
Wheat midge larva on a damaged wheat kernel. Picture credit: Amanda Jorgensen, AAFC-Beaverlodge.
After feeding, larvae remain inside the heads until rain or a moisture event occurs, at which point they drop to the soil, bury themselves, and form a cocoon to overwinter. In the spring, if moisture and temperature requirements are met, larvae leave their cocoons and return to the soil surface, pupating for a period of two weeks.
Wheat fields should be inspected for wheat midge in late June and early July, as wheat heads emerge, and females are laying eggs on the developing heads. Scouting should occur in the evening (after 8:30 PM) on calm, warm (15 ˚C) evenings. The number of adults should be counted on four to five wheat heads in three or four locations. Insecticide applications should be considered if economic thresholds are met. To maintain optimum grain grade, the economic threshold is one adult wheat midge per eight to ten heads during susceptible stages (wheat head emergence up until flowering). To prevent yield loss, the economic threshold is one adult wheat midge per four to five heads.
Varieties of midge tolerant wheat are available to help manage this pest! More information on these can be found at www.midgetolerantwheat.ca.
Are there any natural enemies that stand up to wheat midge? Yes! The parasitoids will be featured in an upcoming issue of Insect of the Week.
Questions or problems accessing the contents of this Weekly Update? Please contact us so we can connect you to our information. Past “Weekly Updates” can be accessed on our Weekly Update page.
TEMPERATURE: This past week (June 20-26, 2022) the average daily temperature on the prairies was 1 °C warmer than the previous week and 1 °C warmer than normal (Fig. 1). Similar to last week, the warmest temperatures were observed across Manitoba and southeastern Saskatchewan. The prairie-wide average 30-day temperature (May 28 – June 26, 2022) was 0.5 °C cooler than the long-term average temperature. Average temperatures have been warmest across the southern prairies (Fig. 2).
Figure 1. Seven-day average temperature (°C) across the Canadian prairies for the period of June 20-26, 2022.Figure 2. 30-day average temperature (°C) across the Canadian prairies for the period of May 28-June 26, 2022.
The growing season (April 1 to June 26, 2022) temperature for the prairies has been 1 °C cooler than climate normal values. A review of specific prairie locations illustrates that Grande Prairie was 1.8 °C cooler than average (Table 1). The growing season has been warmest across western Saskatchewan and southern and central regions of Alberta (Fig. 3).
Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 to June 26, 2022.
Table 1. Growing season (April 1 – June 26, 2022) temperature and rainfall summary for specific locations across the Canadian prairies.
PRECIPITATION: Weekly (June 20-26) rainfall varied across the prairies. Significant rainfall was reported across southeastern Saskatchewan (Weyburn – 82mm) and from Edmonton (66 mm) to Meadow Lake, Saskatchewan (52 mm). The Peace River region and southwestern Saskatchewan reported rainfall amounts that were generally less than 10 mm (Fig. 4). 30-day rainfall accumulation totals have been well above average across Manitoba and Alberta while rainfall accumulation has been well below normal across Saskatchewan (Fig. 5).
Figure 4 Seven-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 20-26, 2022.Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies the past 30 days (May 28-June 26, 2022).
Growing season rainfall for April 1 – June 26, 2022 continues to be greatest across Manitoba and eastern Saskatchewan; growing season rainfall remains below normal across central Saskatchewan and near normal for Alberta (Fig. 6; Table 1).
Figure 6. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1 to June 26, 2022.
The grasshopper (Acrididae: Melanoplus sanguinipes) model predicts development using biological parameters known for the pest species and environmental data observed across the Canadian prairies on a daily basis. Model outputs provided below as geospatial maps are a tool to help time in-field scouting on a regional scale but local development can vary and is only accurately assessed through in-field scouting.
SCOUT NOW – Some areas of the Canadian prairies are presently experiencing high densities of nymphs and economically important species are present. Review lifecycle and damage information for this pest to support in-field scouting.
Warm, dry conditions across central and southern regions of Saskatchewan have resulted in rapid grasshopper development. Model simulations were used to estimate grasshopper development as of June 26, 2022. The grasshopper hatch is nearly complete for the southern prairies (Fig. 1). Hatch is still progressing across the Parkland and Peace River regions. Based on estimates of average nymphal development, first to fifth instar nymphs should be occurring across southern and central regions of all three prairie provinces (Fig. 2).
Figure 1. Predicted migratory grasshopper (Melanoplus sanguinipes) hatch (%) across the Canadian prairies as of June 26, 2022.Figure 2. Predicted migratory grasshopper (Melanoplus sanguinipes) development, presented as average instar, across the Canadian prairies as of June 26, 2022.
Soil moisture conditions in May and June can have significant impacts on wheat midge emergence. Where wheat midge cocoons are present in soil, the 2022 growing season’s rainfall during May and June should be sufficient to terminate diapause and induce the larvae to move to the soil surface.
The map in Figure 1 provides a visual representation of regional estimates of wheat midge movement to the soil surface, where pupal development will occur, then adults will begin to emerge. Remember – the rate of development and timing of adult midge emergence varies at the field level and can only be verified through in-field scouting. Fields within regions receiving sufficient rainfall should scout! Midge flight coinciding with the beginning of anthesis is a crucial point when in-field counts of adults on plants are carefully compared to the economic thresholds.
As of June 26, 2022, model simulations predict that larvae (surface) and pupae are present with limited occurrence of adults. In terms of occurrence of pupae, wheat midge development is most advanced across central Saskatchewan, Manitoba and the Peace River region (British Columbia) (Fig. 1). The first appearance of adults is predicted near Regina and across southern Manitoba (Fig. 2). Model projections for July 3, 2022, indicate that the first appearance of adults should begin across the central prairies and Peace River region over the weekend.
Figure 1. Percent of wheat midge larval population (Sitodiplosis mosellana) that is in the pupal stage, across western Canada,as of June 26, 2022.Figure. 2. Percent of wheat midge population (Sitodiplosis mosellana) that is in the adult stage, across western Canada, as of June 26, 2022.
In-Field Monitoring:When scouting 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. 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. Wheat midge (Sitodiplosis mosellana) laying their eggs on a wheat head. Photo: AAFC-Beav-S. Dufton and A. Jorgensen.
REMEMBER that in-field counts of wheat midge per head remain the basis of the economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (Fig. 4), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.
Figure 4. 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 No. 1 grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage. b) To maintain 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 larval damage.
Wheat midge was featured as the Insect of the Week in 2021 (for Wk07). Be sure to also review wheat midge and its doppelganger, the lauxanid fly, featured as the Insect of the Week in 2019 (for Wk11) – find descriptions and photos to help with in-field scouting! Additionally, the differences between midges and parasitoid wasps were featured as the Insect of the Week in 2019 (for Wk12). Remember – 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 OR pollinators that perform valuable ecosystem services!
Additional information can be accessed by reviewing the Wheat midge pages extracted from the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide” (2018) accessible as a free downloadable PDF in either English or French on our new Field Guides page.
Diamondback moths (DBM; Plutella xylostella) are a migratory invasive species. Each spring adult populations migrate northward to the Canadian prairies on wind currents from infested regions in the southern or western U.S.A. Upon arrival to the prairies, migrant diamondback moths begin to reproduce and this results in subsequent non-migrant populations that may have three or four generations during the growing season.
Model simulations to June 26, 2022, indicate that the first generation of non-migrant adults (based on mid May arrival dates) are currently occurring across the Canadian prairies and that the start of the second generation is emerging in southern Manitoba (Fig. 1).
Figure 1. Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of June 26, 2022.
Spring Pheromone Trap Monitoring of Adult Males: Across the Canadian prairies, spring monitoring is initiated to acquire weekly counts of adult moths attracted to pheromone-baited delta traps deployed in fields. Weekly trap interceptions are observed to generate cumulative counts. Summaries or maps of cumulative DBM data are available for Manitoba, Saskatchewan and Alberta. These cumulative count estimates are broadly categorized to help producers prioritize and time in-field scouting for larvae.
In-Field Monitoring:Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 2) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.
Figure 2. Diamondback larva measuring ~8mm long. Note brown head capsule and forked appearance of prolegs on posterior.
The economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1 m² (approximately 2-3 larvae per plant). Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m² (approximately 1-2 larvae per plant).
Figure 3. Diamondback moth pupa within silken cocoon.
1. REVERSE TRAJECTORIES (RT) Since May 1, 2022, the majority of reverse trajectories that have crossed the prairies have originated from the Pacific Northwest (Idaho, Oregon and Washington). This past week (June 21-27, 2022) the number of incoming trajectories was lower than the week of June 14-20, 2022 (Fig. 1).
Figure 1. Average number (based on a 5-day running average) of reverse trajectories (RT) crossing the prairies for the period of June 1-27, 2022.
a. Pacific Northwest (Idaho, Oregon, Washington) – The majority of Pacific Northwest reverse trajectories continue to pass over southern and central Alberta and western Saskatchewan (Fig. 2). This past week (June 21-27, 2022) the ECCC model predicted that 77 reverse trajectories would cross the prairies. This is significantly less than the number of reverse trajectories predicted for the period of June 14-20 (n=124).
Figure 2. Total number of dates with reverse trajectories originating over the Idaho, Oregon, and Washington that have crossed the prairies between April 1 and June 27, 2022.
b. Mexico and southwest USA (Texas, California) – This week (June 21-27, 2022), a total of 13 reverse trajectories were predicted to cross the prairies (n=44 for June 14-20). Most reverse trajectories from this region of southern North America have crossed Manitoba during the 2022 growing season.
Figure 3. The total number of dates with reverse trajectories originating over Mexico, California and Texas that have crossed the prairies between April 1 and June 27, 2022.
c. Oklahoma and Texas – This week reverse trajectories have passed over Manitoba and Watrous, Saskatchewan (Fig. 4). This week there were significantly fewer (n=5) reverse trajectories than for the period of June 14-20, 2022 (n=33).
Figure 4. The total number of dates with reverse trajectories originating over Texas and Oklahoma that have crossed the prairies between May 1 and June 27, 2022.
d. Nebraska and Kansas – This past week (June 21-27, 2022), reverse trajectories originating from Kansas and Nebraska have crossed Manitoba and Yorkton, Saskatchewan (Fig. 5). The ECCC model predicted that 5 reverse trajectories passed over the prairies. This is a significant decrease from the previous week (n=51).
Figure 5. The total number of dates with reverse trajectories originating over Kansas and Nebraska that have crossed the prairies between April 1 and June 27, 2022.
2. FORWARD TRAJECTORIES (FT) The following map presents the total number of dates (since April 1, 2022) with forward trajectories (originating from Mexico and USA) that were predicted to cross the Canadian prairies (Fig. 6). This week (June 21-27, 2022) there was a decrease in the number of (n=19) forward trajectories predicted to cross the prairies (last week n=50). Results indicate that the greatest number of forward trajectories entering the prairies have originated from the Pacific Northwest (Idaho, Oregon, Washington), Montana and Wyoming.
Figure 6. Total number of dates with forward trajectories, originating from various regions of the United States and Mexico, crossing the prairies between April 1 and June 27, 2022.
View historical PPMN wind trajectory reports by following this link which sorts the reports from most recent to oldest.
The Pests and Predators Field Guide is filled with helpful images for quick insect identification and plenty of tips to manage the pests AND natural enemies in your fields. Claim your free copy at http://fieldheroes.ca/fieldguide/ or download a free copy to arm your in-field scouting efforts!
Review the Sweep-net Video Series including: • How to sweep a field. Meghan Vankosky (Agriculture and Agri-Food Canada-Saskatoon). Published online 2020. • What’s in my sweep-net? Meghan Vankosky (Agriculture and Agri-Food Canada-Saskatoon). Published online 2020. • Why use a sweep-net? Meghan Vankosky (Agriculture and Agri-Food Canada-Saskatoon). Published online 2020.
Provincial entomologists provide insect pest updates throughout the growing season so link to their information:
MANITOBA’SCrop Pest Updates for 2022 are up and running! Access a PDF copy of the June 29, 2022 issue here. Bookmark their Crop Pest Update Index to readily access these reports and also bookmark their insect pest homepage to access fact sheets and more! • Seedcorn maggot and wheat stem maggot in MB were new additions to the June 29 issue. • Diamondback moth pheromone trap monitoring update for MB – Traps will come down at the end of this week. Review the detailed summary of cumulative trap counts from 52 sites deployed across the province. • Armyworm pheromone trap monitoring is underway in MB – Review this summary (as of June 22, 2022) of counts compiled from Manitoba, Eastern Canada and several northeast states of the United States.
ALBERTA’SInsect Pest Monitoring Network webpage links to insect survey maps, live feed maps, insect trap set-up videos, and more. There is also a Major Crops Insect webpage. The new webpage does not replace the Insect Pest Monitoring Network page. Remember, AAF’s Agri-News occasionally includes insect-related information. Twitter users can connect to #ABBugChat Wednesdays at 10:00 am. • Wheat midge pheromone monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. • Cabbage seedpod weevil monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. • Bertha armyworm pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. • Diamondback moth pheromone trap monitoring update for AB – Cumulative counts arising from weekly data are available so refer to the Live Map. • Cutworm live monitoring map for AB – Reports continue to come in so refer to the Live Map to review areas where cutworms are being found. Use this online form to report cutworms in Alberta.
This week’s insect, the strawberry blossom weevil (Anthonomus rubi) is a recent invader to British Columbia. It is native to Europe, Asia, and parts of North Africa. As its name implies it is a serious pest of strawberries, however, it does have a much wider host range including many plants in the family Rosaceae – raspberries, blackberries, and roses to name a few.
It was first found in Abbotsford, British Columbia (BC) in 2019 on raspberries and has since been found to be established throughout the Fraser Valley of BC on cultivated and wild host plants. This is the first report of strawberry blossom weevil in North America. Due to the presence of strawberry blossom weevil in BC, the United States Department of Agriculture Animal and Plant Health Inspection Service (APHIS) amended entry requirements for Fragaria, Rubus, and Rosa plants. The USA now requires a phytosanitary certificate to move these plants from Canada into the USA (Federal Order DA-2021-25).
The strawberry blossom weevil lays its eggs in closed buds and clips the stem just below to prevent further bud development.
The egg hatches and the weevil larva develops inside of the damaged bud. Once mature, an adult weevil chews a hole in the bud from which it emerges. It completes a single generation per year. In Europe, bud losses associated with strawberry blossom weevil damage range from 5 to 90% and have led to yield losses over 60%. The strawberry blossom weevil can be confused with the strawberry clipper weevil (Anthonomus signatus) in Canada due to its similar biology and crop damage.
Although there is a historical record of strawberry clipper weevil being in BC, it is primarily a pest in berry crops in eastern Canada and has not been detected during our surveys in 2020-2022 in southwest BC. Adult strawberry blossom weevils are small (2.5-3.0 mm), black, with a small white patch of scales on the scutellum (back), and a long slender rostrum (snout). Larvae, found within damaged buds are c-shaped, with a yellowish-brown head capsule and cream coloured body that grows to 2.5 to 3 mm.
Adult weevils naturally drop when disturbed so they can be detected using beat sampling (tapping) in plants. They are also detectable using yellow sticky cards. Visual surveys for damaged buds with severed stems can also be useful when searching for strawberry blossom weevil.
Although this pest has not been detected to date on the Prairies, a nationwide survey is underway this summer to delineate the distribution of this pest in Canada. In collaboration with Agriculture and Agri-Food Canada, a Story Map has been created to provide an easily digestible summary of the survey underway using pictures, text, and interactive maps all accessible here. We are looking for community-based records of strawberry blossom weevil so, if you would like to get involved, please submit pictures of any suspected strawberry blossom weevil to our iNaturalist project (Anthonomus rubi in North America · iNaturalist).
Week 8 and several days of unusually warm weather are going to make field scouting even more important! Be sure to catch the Insect of the Week – it’s cabbage seedpod weevil! This week find updates to predictive model outputs for grasshoppers, wheat midge, bertha armyworm, and diamondback moth plus a lot more to help prepare for in-field scouting!
Stay safe and good scouting to you!
Questions or problems accessing the contents of this Weekly Update? Please contact us so we can connect you to our information. Past “Weekly Updates” can be accessed on our Weekly Update page.
TEMPERATURE: This past week (June 14-20, 2021), weekly temperatures were above normal and rainfall amounts for Saskatchewan and Manitoba were less than 5 mm. The warmest temperatures were observed across the southern and central regions of Alberta as well as western Saskatchewan (Fig. 1).
Figure 1. 7-day average temperature (°C) observed across the Canadian prairies for the period of June 14 – 20, 2021.
Across the prairies, the average 30-day (May 22 – June 20) temperature was 1.4 °C warmer than climate normal values. The warmest temperatures were observed across southern Manitoba (Fig. 2). The 2021 growing season (April 1 – June 20, 2021) has been characterized by near normal temperatures. The warmest temperatures have occurred across southern and central regions of the three prairie provinces (Fig. 3).
Figure 2. 30-day average temperature (°C) observed across the Canadian prairies for the period of May 22 – June 20, 2021.Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1 – June 20, 2021.
PRECIPITATION: This week, the highest rainfall amounts were reported across the Peace River region. Minimal rainfall was reported across most of Manitoba (Fig. 4). Rainfall amounts for the period of May 22-June 20 (30-day accumulation) were above normal (150 % of long-term average values). Rainfall amounts have been above normal for northeastern Alberta, most of Saskatchewan, and western and central regions of Manitoba (Fig. 5).
Figure 4. 7-day cumulative rainfall (mm) observed across the Canadian prairies for the period of June 14 -20, 2021.Figure 5. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 22 – June 20, 2021
The average growing season (April 1 – June 20) precipitation was 116 % of normal with the greatest precipitation occurring across central Alberta, eastern Saskatchewan, including Regina, and an area extending from Brandon to Winnipeg. Below normal rainfall has been reported across western Saskatchewan and southern Alberta (Fig. 6).
Figure 7. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1-June 20, 2021.
Access background information for how and why wind trajectories are monitored in this post.
1. REVERSE TRAJECTORIES (RT) Since June 16, 2021, there have been a decreasing number of reverse trajectories that moved north from the Pacific Northwest (Idaho, Oregon and Washington), Texas, Oklahoma, Kansas and Nebraska (Fig. 1).
Figure 1. The average number (based on a 5-day running average) of reverse trajectories that have crossed the prairies for the period of May 21 – June 21, 2021.
a. Pacific Northwest (Idaho, Oregon, Washington) – This week (June 16-21, 2021) there have been 43 trajectories that have crossed Alberta, Manitoba and Saskatchewan that originated in the Pacific Northwest (Fig. 2).
Figure 2. Total number of dates with reverse trajectories originating over the Pacific Northwest (Idaho, Oregon, and Washington) and have crossed the prairies between March 24 and June 21, 2021.
b. Mexico and southwest USA (Texas, California) – This week (June 16 – 21, 2021) there have been 3 trajectories that originated in Mexico or the southwest USA that have crossed the prairies.
c. Oklahoma and Texas – This week (June 16 – 21, 2021) there have been 4 trajectories originating in Oklahoma or Texas that have passed over the prairies.
d. Kansas and Nebraska – This week (June 16 – 21, 2021) there have been 8 trajectories that originated in Kansas or Nebraska that passed over the prairies.
2. FORWARD TRAJECTORIES (FT) a. Since June 9, 2021, there has been a steady decrease in the number of forward trajectories that are predicted to cross the prairies (Fig. 3). The dates on the graph report when the trajectories originated in the USA (blue bars). These trajectories generally require 3-5 days to enter the prairies (red line).
Figure 3. The average number (based on a 5 day running average) of forward trajectories that were predicted to cross the prairies for the period of May 21-June 21, 2021.
Wheat midge (Sitodiplosis mosellana) overwinter as larval cocoons in the soil. Soil moisture conditions in May and June can have significant impacts on wheat midge emergence. Adequate rainfall promotes termination of diapause and movement of larvae to the soil surface where pupation occurs. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. 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. The Olfert et al. (2020) model indicated that dry conditions may result in: a. Delayed adult emergence and oviposition b. Reduced numbers of adults and eggs
Wheat midge model simulations indicate that the majority of the larval population has moved to the soil surface (Fig. 1). Dry conditions in the Peace River region have resulted in delayed development of larval cocoon populations. First appearance of pupae should be occurring near Winnipeg, Brandon, Regina and Edmonton areas (Fig. 2).
Figure 1. Percent of the wheat midge (Sitodiplosis mosellana) larval population that has moved to the soil surface and is preparing to pupate across western Canada, based on weather conditions up to June 20, 2021.Figure 2. Percent of wheat midge (Sitodiplosis mosellana) population that is in the pupal stage, located near the soil surface across western Canada, based on weather conditions up to June 20, 2021.
The model was projected to July 6 to determine potential development at Regina, Lacombe and Grande Prairie over the next two weeks. Compared to Lacombe and Grande Prairie, Regina has been warmer and wetter for the period of May 1 – June 20, 2021 (Fig.3). The first appearance of adults in the Regina area is expected to occur this week and initial oviposition is predicted to occur by the end of June. Emergence patterns for southern Manitoba are predicted to be similar to Regina.
Figure 3. Predicted development of wheat midge (Sitodiplosis mosellana) populations near Regina, Saskatchewan as of June 20, 2021 (projected to July 6, 2021).
Cooler temperatures at Lacombe are predicted to result in slower development of larvae and pupae (relative to Regina) with the first emergence of adults predicted to occur during the last week of June (Fig. 4). Cooler and dryer conditions in the Peace River region will impact the movement of larvae to the soil surface, resulting in reduced adult emergence and later appearance of adults; adult emergence is predicted to occur during the first week of July (Fig. 5).
Figure 4. Predicted development of wheat midge (Sitodiplosis mosellana) populations near Lacombe, Alberta as of June 20, 2021 (projected to July 6, 2021).Figure 5. Predicted development of wheat midge (Sitodiplosis mosellana) populations near Grande Prairie, Alberta as of June 20, 2021 (projected to July 6, 2021).
Based on predictions for adult emergence, monitoring for the appearance of wheat midge adults should begin this week in Manitoba and Saskatchewan and later next week across Alberta in areas where wheat midge is expected to occur. It is especially important that adult monitoring be prioritized in regions with high risk based on the 2020 survey (Fig. 6).
Figure 6. 2021 Wheat midge forecast map which represents regions at risk of damage to cereal crops due to wheat midge, based on the number of un-parasitized wheat midge larval cocoons in soil samples collected in the fall of 2020.
Monitoring:When scouting 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. 7). 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 7. 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 the economic threshold decision. Also remember that the parasitoid, Macroglenes penetrans (Fig. 8), is actively searching for wheat midge at the same time. Preserve this parasitoid whenever possible and remember insecticide control options for wheat midge also kill these beneficial insects who help reduce midge populations.
Figure 8. 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 No. 1 grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage. b) To maintain 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 larval damage.
Wheat midge was featured as the Insect of the Week in 2021 (for Wk07). Be sure to also review wheat midge and its doppelganger, the lauxanid fly, featured as the Insect of the Week in 2019 (for Wk11) – find descriptions and photos to help with in-field scouting! Additionally, the differences between midges and parasitoid wasps was featured as the Insect of the Week in 2019 (for Wk12). Remember – 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 OR pollinators that perform valuable ecosystem services!
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.
Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of June 20, 2021. As of June 20, hatch is predicted to be underway across most of the prairies with a prairie average of 69 % (versus 45 % last week). Percent hatch was greater than 90 % across most of Manitoba, Saskatchewan, and southern Alberta. Development in the central and Peace River regions of Alberta has been significantly slower than the rest of the prairies (Fig. 1).
Figure 1. Predicted grasshopper (Melanoplus sanguinipes) hatch (%) across the Canadian prairies as of June 20, 2021.
Development of grasshopper nymphs, based on average instar, should be greatest across southern Manitoba and southern Saskatchewan (Fig. 2). Grasshopper populations south of Winnipeg are predicted to be mostly in the 3rd and 4th instar stages. Across the prairies, nymph development, as of June 20, 2021, is well ahead of long-term average values across most of the prairies (Fig. 3).
Figure 2 Predicted grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of June 20, 2021.Figure 3. Long term average predicted grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of June 20, based on climate normals data.
The model was projected to July 6 to determine potential development at Winnipeg and Lethbridge over the next two weeks. Results suggest that by July 6, Winnipeg populations will primarily be in the fourth and fifth instars with the first appearance of adults (Fig. 4). Development near Lethbridge is predicted to be slower, with populations being mostly in the third and fourth instars (Fig. 5). Producers are advised to monitor roadsides and field margins to assess the development and densities of local grasshopper populations.
Figure 4. Predicted development, presented as the average instar, of Melanoplus sanguinipes populations near Winnipeg, Manitoba as of June 20, 2021 (projected to July 6, 2021).Figure 5. Predicted development, presented as the average instar, of Melanoplus sanguinipes populations near Lethbridge, Alberta as of June 20, 2021 (projected to July 6, 2021).
Grasshopper Scouting Steps: ● Review grasshopper diversity and scouting information including photos of both nymphs, adults and non-grasshopper species to aid in-field scouting and accurately apply thresholds for grasshoppers. ● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin. ● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump. ● Grasshoppers that jump/fly through the field of view within a one-meter width in front of the observer are counted. ● A meter stick can be carried as a visual tool to give perspective for a one-meter width. However, after a few stops, one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance. ● At the endpoint, the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure. ● Compare counts to the following damage levels associated with pest species of grasshoppers: 0-2 per m² – None to very light damage 2-4 per m² – Very light damage 4-8 per m² – Light damage 8-12 per m² – Action threshold in cereals and canola 12-24 per m² – Severe damage 24 per m² – Very severe damage For lentils at flowering and pod stages, >2 per m² will cause yield loss. For flax at boll stages, >2 per m² will cause yield loss. ● More practically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” requires careful consideration:
Scouting for grasshoppers is a priority across the Canadian prairies with nymphs now active in fields from Manitoba to the Peace River region! Several entomologists have kindly offered photos to aid in-field scouting efforts so take these along and use these important points to d more accurately identify grasshopper nymphs and adults:
Traditionally, the economically damaging species of grasshoppers on the Canadian prairies include: • Migratory (Melanoplus sanguinipes; Figs. 1, 2, 3) • Clear-winged (Camnula pellucida; Fig. 3, 4, 5) • Two-striped (Melanoplus bivittatus; Fig. 6, 7, 8) • Packard’s (Melanoplus packardii; Fig. 9) • And more recently Bruner’s grasshopper (Melanoplus bruneri; Fig. 10)
Not everything that hops is a grasshopper! Several species of native slant-faced grasshoppers (normally not causing economic damage; Fig. 11) typically emerge earlier in the spring than economic pest species. Several species of leafhoppers and their closely related froghopper, and treehopper relatives also hop. In fact, early instar grasshopper nymphs are similar in size to leafhopper adults (Fig. 12). Roadside vegetation can be heavily populated by non-damaging leafhoppers and native katydids (Fig. 13) – a sweep-net will allow comparison and improve identification. Katydids resemble grasshoppers in an important way; egg, nymphal instar, and adult stages appear over similar time frames through the growing season.
Monitoring and management of the various pest species of grasshoppers ideally focuses on nymphal instar stages. Compared to adults, early instar grasshopper nymphs are at the beginning of the consumptive portion of life, plus nymphs lack full-sized wings (and have only small wing buds) so they are easier to count and manage. Pest species like the clear-winged grasshopper (C. pellucida) develop through five nymphal instar stages then mature to winged adults.
Figure 1. Fifth instar nymph of (tentatively identified) migratory grasshopper (M. sanguinipes). Photo: AAFC-Saskatoon – Jonathon Williams. Note: each unit represents 1 mm so nymph is ~16 mm long. Figure 2. In situ photo of nymph of (tentatively identified) migratory grasshopper (M. sanguinipes). Photo: John Gavloski.Figure 3. Adult (tentatively identified as) migratory grasshopper (M. sanguinipes). Photo: AAFC-Saskatoon – Jonathon Williams. Note: Wings extend down the length of the abdomen.Figure 4. Life stages of clear-winged grasshopper (C. pellucida) including egg, first-fifth instar nymphs and adult (L-R). Photo: AAFC-Saskatoon-Ralph Underwood.Figure 5. In situ photo of first instar clear-winged grasshopper (C. pellucida). Photo: Dan Johnson.Figure 6. Grasshopper eggs (tentatively identifed as two-striped or M. bivattus) exposed in soil near Carman MB in 2010. Photo: John Gavloski.Figure 7. Nymph of two-striped grasshopper (M. bivattus) resting on peas growing near Carman MB in 2019. Photo: John Gavloski. Note: Wing buds are visible and will be replaced by wings stretching the length of the abdomen when nymph matures to adult.Figure 8. Various developmental stages of two-striped grasshopper (M. bivattus) featuring an early and late instar nymph (top and left, respectively) plus adult (right). Photo: John Gavloski.Figure 9. Photo features (tentatively identified) third instar nymph of Packard’s grasshopper (Camnulla pellucida). Photo: AAFC-Saskatoon-Jonathon Williams. Note: Each unit is 1 mm so nymph is ~6 mm long. Figure 10. Early instar nymph of Bruner’s grasshopper (M. bruneri). Photo: Dan Johnson.Figure 11. A slant-faced grasshopper nymph (tentatively identified as a second instar nymph of Chorthippus curtipennis) featuring the characteristically angled head that is the hallmark of several native species of traditionally non-economically damaging grasshoppers. Photo: AAFC-Saskatoon-Jonathon Williams.Figure 12. Comparison of early instar grasshopper nymph (left) and adult leafhopper (right) collected in roadside vegetation – both are approximately the same size and both ‘hop’ when disturbed. Photo: John Gavloski.Figure 13. Katydid nymph on roadside vegetation near Dauphin MB in 2021. Photo: John Gavloski. Note: Tiny wing buds are visible on anterior end of abdomen.
ECONOMIC THRESHOLDS – The general economic threshold for grasshoppers in cereals is 8-12 per square metre but will vary by crop and growing conditions. – Grasshopper densities exceeding 8-12 per square metre usually warrant control measures. – More specifically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” will require careful consideration.
Model simulations to June 20, 2021, indicate that the development of bertha armyworm (BAW) (Mamestra configurata) pupae are nearly complete. Other than the Peace River region, BAW adults should now be active across the prairies (Fig. 1). Model simulations indicate that BAW oviposition has begun across southern areas of Manitoba, Saskatchewan and localized areas in Alberta (Fig. 2).
Figure 1. Predicted percent of bertha armyworm (Mamestra configurata) population that is in the adult stage (% of population) across the Canadian prairies as of June 20, 2021.Figure 2. Predicted percent of bertha armyworm (Mamestra configurata) population that is in the egg stage (% of population) across the Canadian prairies as of June 20, 2021.
Model projections to July 6 predict that development near Brandon will be more advanced than development near Grande Prairie (Figs. 3 and 4). BAW populations in southern Manitoba are predicted to be predominantly in the larval stage by early July whereas BAW populations near Grande Prairie will be in the adult and egg stages.
Figure 3. Predicted development of bertha armyworm (Mamestra configurata) populations near Brandon, Manitoba as of June 20, 2021 (projected to July 6, 2021).Figure 4. Predicted development of bertha armyworm (Mamestra configurata) populations near Grande Prairie, Alberta as of June 20, 2021 (projected to July 6, 2021).
Provincial insect pest monitoring networks in Manitoba, Saskatchewan and Alberta are now compiling cumulative counts of adults intercepted from the pheromone-baited green unitraps deployed in fields across the prairies. Review the Provincial Insect Pest Report Links to find summaries or link to the latest bertha armyworm moth counts by clicking the appropriate province’s reporting info for Manitoba, Saskatchewan or Alberta.
Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting. Use the images below (Fig. 6) to help identify the various stages. Review the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm!
Figure 6. The egg stage (A), larval stage (B), pupal stage (C), and adult stage (D) of bertha armyworm. Photos: Jonathon Williams (AAFC-Saskatoon).
Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also, refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” which is a free downloadable document as both an English-enhanced or French-enhanced version.
Diamondback moths (DBM) (Plutella xylostella) are a migratory invasive species. Each spring adult populations migrate northward to the Canadian prairies on wind currents from infested regions in the southern or western U.S.A. Upon arrival to the prairies, migrant diamondback moths begin to reproduce and this results in subsequent non-migrant populations that may have three or four generations during the growing season.
Model simulations to June 20, 2021, indicate that the first generation of non-migrant adults are currently emerging across the Canadian prairies and that the start of the second generation is occurring in southern Manitoba (Fig. 1).
Figure 1 Predicted number of non-migrant generations of diamondback moth (Plutella xylostella) expected to have occurred across the Canadian prairies as of June 20, 2021.
So far, Manitoba, Saskatchewan, Alberta and the BC Peace are all reporting relatively low numbers of intercepted DBM in pheromone traps (read provincial insect pest report links) despite the fact that favourable wind trajectories have passed over the Canadian prairies from southern regions of North America (review wind trajectory reports for 2021). Even so, once DBM are present in an area, it is important to monitor individual canola fields for larvae. Warm growing conditions can quickly translate into multiple generations in a very short time so use the following photos to help identify larvae (Fig. 2), pupae (Fig. 3), or adults (Fig. 4)!
Monitoring:Remove plants in an area measuring 0.1 m² (about 12″ square), beat them onto a clean surface and count the number of larvae (Fig. 2) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.
Figure 2. Diamondback larva measuring ~8mm long. Note brown head capsule and forked appearance of prolegs on posterior.
The economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1 m² (approximately 2-3 larvae per plant). Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m² (approximately 1-2 larvae per plant).
Figure 3. Diamondback moth pupa within silken cocoon.
Monitoring is already underway for cabbage seedpod weevil (Ceutorhynchus obstrictus; CSPW) in southern areas of the prairies – it’s the Insect of the Week for Wk08! There is one generation of CSPW per year and the overwintering stage is the adult which is an ash-grey weevil measuring 3-4mm long (Refer to lower left photo). Adults typically overwinter in soil beneath leaf litter within shelter belts and roadside ditches.
Monitoring:
Begin sampling when the crop first enters the bud stage and continue through the flowering.
Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.
Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.
Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.
An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts).
Consider making insecticide applications late in the day to reduce the impact on pollinators. Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.
High numbers of adults in the fall may indicate the potential for economic infestations the following spring.
Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss. Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo). Eggs are oval and an opaque white, each measuring ~1mm long. Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.
There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo). The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds. A single larva consumes about 5 canola seeds. The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell. Approximately 10 days later, the new adult emerges to feed on maturing canola pods. Later in the season, these new adults migrate to overwintering sites beyond the field.
Albertan growers can report and check the live map for CSPW posted by Alberta Agriculture and Forestry (screenshot provided below for reference; retrieved24Jun2021).
On the Canadian prairies, lygus bugs (Heteroptera: Miridae) are normally a complex of several native species usually including Lygus lineolaris, L. keltoni, L. borealis, L. elisus although several more species are distributed throughout Canada. The species of Lygus forming the “complex” can vary by host plant, by region or even seasonally.
Lygus bugs are polyphagous (i.e., feed on plants belonging to several Families of plants) and multivoltine (i.e., capable of producing multiple generations per year). Both the adult (Fig. 1) and five nymphal instar stages (Fig. 2) are a sucking insect. Adults overwinter in northern climates. The economic threshold for Lygus in canola is applied at late flower and early pod stages.
Figure 1. Adult Lygus lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
Figure 2. Fifth instar lygus bug nymph (3-4 mm long) (photo: AAFC-Saskatoon).
Damage: Lygus bugs have piercing-sucking mouthparts and physically damage the plant by puncturing the tissue and sucking plant juices. The plants also react to the toxic saliva that the insects inject when they feed. Lygus bug infestations can cause alfalfa to have short stem internodes, excessive branching, and small, distorted leaves. In canola, lygus bugs feed on buds and blossoms and cause them to drop. They also puncture seed pods and feed on the developing seeds causing them to turn brown and shrivel.
Scouting tips to keep in mind: Begin monitoring canola when it bolts and continue until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.
Sample the crop for lygus bugs on a sunny day when the temperature is above 20 °C and the crop canopy is dry. With a standard insect net (38 cm diameter), take ten 180 ° sweeps. Count the number of lygus bugs in the net. Sampling becomes more representative IF repeated at multiple spots within a field so sweep in at least 10 locations within a field to estimate the density of lygus bugs. In fact, sampling is most accurate when repeated at a total of 15 spots within the field. Samples can be taken along or near the field margins. Calculate the cumulative total number of lygus bugs and then consult the sequential sampling chart (Figure 3).
Figure 3. Sequential sampling for lygus bugs at late flowering stage in canola.
If the total number is below the lower threshold line (Fig. 3), no treatment is needed. If the total is below the upper threshold line, take more samples. If the total is on or above the upper threshold line, calculate the average number of lygus bugs per 10-sweep sample and consult the economic threshold tables (Tables 1 and 2).
The economic threshold for lygus bugs in canola covers the end of the flowering (Table 1) and the early pod ripening stages (Table 2). Once the seeds have ripened to yellow or brown, the cost of controlling lygus bugs may exceed the damage they will cause prior to harvest, so insecticide application is not warranted. Consider the estimated cost of spraying and expected return prior to making a decision to treat a crop.
Remember that insecticide applications at bud stage in canola have not been proven to result in an economic benefit in production. The exception to this is in the Peace River region where early, dry springs and unusually high densities of lygus bug adults can occasionally occur at bud stage. In this situation, high numbers of lygus bugs feeding on moisture-stressed canola at bud stage is suspected to result in delay of flowering so producers in that region must monitor in fields that fail to flower as expected.
Biological and monitoring information related to Lygus in field crops is posted by the provinces of Manitoba or Alberta fact sheets or the Prairie Pest Monitoring Network’s monitoring protocol. Also refer to the Lygus pages within the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English or French versions are available.
Track the migration of the Monarch butterflies as they move north by checking the 2021 Monarch Migration Map! A screenshot of the map has been placed below as an example (retrieved 24Jun2021) but follow the hyperlink to check the interactive map. They’ve reached more sites in Saskatchewan and one site in southern Alberta!
The NEW Pests and Predators Field Guide is filled with helpful images for quick insect identification and plenty of tips to manage the pests AND natural enemies in your fields. Claim your free copy at http://fieldheroes.ca/fieldguide/ or download for free to arm your in-field scouting efforts!
Provincial entomologists provide insect pest updates throughout the growing season so link to their information:
MANITOBA’SCrop Pest Updates for 2021 are now available – access the June 23, 2021 report here. Be sure to bookmark their Crop Pest Update Index to readily access these reports! Also, bookmark their insect pest homepage to access fact sheets and more! • Bertha armyworm pheromone trap monitoring update for MB – Cumulative counts arising from weekly data are available here. Happily, the initial counts are very low so far. • Diamondback moth pheromone trap monitoring update for MB – Trapping has drawn to a close for 2021. Access the summary here. Only 59 traps intercepted moths and the highest cumulative count was 142 moths near Selkirk. Access the summary (as of June 22, 2021). At this point, in-field scouting for larvae remains important.
SASKATCHEWAN’SCrop Production News have begun to roll out for 2021 and are accessible now! Access Issue #1 online which includes a crop protection laboratory update including how to submit samples, information on curculios on fruit crops, and information for scouting flea beetles and assessing damage. Be sure to bookmark their insect pest homepage to access important information! • Bertha armyworm pheromone trap monitoring update for SK – Cumulative counts arising from weekly data will be available here shortly. • Diamondback moth pheromone trap monitoring update for SK – Monitoring has drawn to a close for 2021. Review the final DBM counts. Extremely low numbers have been intercepted. Province-wide, <45 moths have been intercepted so far (2021Jun10 Carter, pers. comm.). At this point, in-field scouting for larvae remains important.
ALBERTA’SInsect Pest Monitoring Network webpage links to insect survey maps, live feed maps, and insect trap set-up videos and more. There is also a Major Crops Insect webpage. The new webpage does not replace the Insect Pest Monitoring Network page. Remember, AAF’s Agri-News occasionally includes insect-related information or Twitter users can connect to #ABBugChat Wednesdays at 10:00 am. • Wheat midge pheromone trap monitoring update for AB – Cumulative counts arising from weekly data will be available shortly so refer to the Live Map. • Bertha armyworm pheromone trap monitoring update for AB – Cumulative counts arising from weekly data have begun so refer to the Live Map. • Diamondback moth pheromone trap monitoring update for AB – Trapping is drawn to a close for 2021. Refer to the Live Map which reports extremely low numbers of moths intercepted so far (<45 province-wide as of 24Jun2021). At this point, in-field scouting for larvae remains important. • Cutworm reporting tool – Refer to the Live Map which still reports only four sites with cutworms (as of 17Jun2021).
Cabbage seedpod weevil (Alberta Agriculture and Rural Development)
First discovered in the Prairie region during the 1990s, the cabbage seedpod weevil is a pest in both its adult and larval stages. Cabbage seedpod weevils emerge from overwintering in the spring as soil temperatures warm, and utilize plants like canola, brown and wild mustard to sustain larval development.
Both adult and larval stages can cause crop damage. As adults, cabbage seedpod weevils can cause canola flower budblasting as they feed on developing flowers, and later in the season their appetites will turn to canola pods. However, it is the cabbage seedpod weevil larvae causes the most damage. During their development, these larvae will bore into seed pods and consume the seeds within. Infested pods are more prone to shattering and are more susceptible to fungal infections.
Cabbage seedpod weevil damage to canola (AAFC)
Adult cabbage seedpod weevils are 3–4 mm long with a long narrow snout. When disturbed, these insects “play dead,” resuming activity when the perceived threat has passed. Mature larvae are 2–3 mm long with a whitish body, brown head and anal plate, and 3 pairs of thoracic legs.
Agriculture and Agri-Food Canada (AAFC) and Environment and Climate Change Canada (ECCC) have been working together to study the potential of trajectories for monitoring insect movements since the late 1990s.
Another BIG Weekly Update – several predictive model updates have been generated this week! Find updated information for bertha armyworm, grasshoppers, cereal leaf beetle, alfalfa weevil, wheat midge and pea leaf weevil. Keep scrolling down and it’s time to get in fields to scout!
This week’s Insect of the Week feature crop is corn, which has become more prominent on the Prairies. Our feature entomologist this week is Maya Evenden (Department of Biological Sciences, University of Alberta).
Corn Crop cc by 2.0 Edwin Ijsman
While the bulk of Canadian corn is grown in Ontario and Quebec, the Prairies are not without robust corn production, split between corn for grain and corn for silage. In 2019, corn was grown on 404,800 hectares (992,300 acres) across the Prairies, producing 5.44 million metric tonnes (6 million US tons). Over three quarters of this amount was corn for silage, and the remainder corn for grain.
Name: Maya Evenden Affiliation: Department of Biological Sciences, University of Alberta Contact Information: mevenden@ualberta.ca; @MayaEvenden on twitter
How do you contribute in insect monitoring or surveillance on the Prairies?
My research group develops semiochemical-based monitoring tools that target insects of environmental and economic impact in Alberta. For field crop pests, we have developed and tested semiochemical-based monitoring tools for 1) diamondback moth; 2) pea leaf weevil; 3) red clover casebearer 4) cutworms and 5) wheat midge.
We also work on other non-target species that are captured in monitoring traps (bycatch). This provides information on biodiversity and community composition of arthropods in managed agroecosystems.
I am an active member of the Prairie Pest Monitoring Network.
In your opinion, what is the most interesting field crop pest on the Prairies?
I am partial to the Bertha armyworm because:
It’s a moth (and I love moths)
Larvae march like an army
It is a native insect that exploits agricultural crops planted in its habitat
Pheromone-based monitoring is useful because moths can be caught before eggs are laid in the field to warn producers of the current season’s feeding damage
What is your favourite beneficial insect?
I like the diamondback moth parasitoid, Diadegma insulare because:
It is a specialist on diamondback moth (although it will parasitize other Lepidoptera)
It tracks diamondback moth migration to the Prairie Provinces
It can result in a high level of parasitism of diamondback moth populations
It is highly susceptible to pesticide applications
Tell us about an important project you are working on right now.
We are currently documenting the biodiversity and abundance of ground beetles in pulse crops in Alberta. We will find out the community composition of ground beetle predators in pulse fields, the landscape features with which they are associated, and what they eat. My PhD student Maggie MacDonald is leading this research and we are collaborating with Dr. Boyd Mori on the assessment of beetle gut content using molecular methods.
What tools, platforms, etc. do you use to communicate with your stakeholders?
We communicate with stakeholders through in-person updates at field days and annual meetings. In addition, we publish updates in grower magazines (i.e. Top Crop Manager), newsletters and grower websites. We communicate with grower organizations through research updates. I also communicate directly with stakeholders through email and twitter @MayaEvenden.
Weather synopsis – This week (May 21-28, 2019) cool, dry conditions continued to occur across the prairies. Though temperatures are warming up, early growing season daily average temperatures continue to be cooler than normal.
Throughout this past week, the average temperature was approximately 1 °C cooler than normal (Fig. 1). Compared to last week, the prairie-wide average daily temperature was 3 °C warmer. The warmest temperatures were observed across the Parkland region of the prairies.
Figure 1. Average temperature (°C) across the Canadian prairies the past seven days (May 22-28, 2019).
The average 30-day temperatures were approximately 3 °C cooler than average (Fig. 2).
Figure 2. Average temperature (°C) across the Canadian prairies the past 30 days (April 28-May 28, 2019).
Seven-day cumulative rainfall (Fig. 3) indicated that minimal rain was observed across large areas of SK. Most locations reported less than 5 mm. Wetter conditions were reported in a corridor between Lethbridge and Calgary AB. Most of MB and southeast SK had rainfall amounts that were greater than 10 mm (Fig. 3).
Figure 3. Cumulative precipitation observed the past seven days across the Canadian prairies (May 22-28, 2019). Figure 4. Mean temperature differences from Normal across the Canadian prairies from April 30-May 27, 2019. Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (30May2019). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true
Across the prairies, rainfall amounts for the past 30 days (April 28-May 28, 2019) have been approximately 50% of normal (Fig. 6). The 30-day rainfall totals have improved in MB and southwest SK.
Figure 5. Cumulative precipitation observed the past 30 days across the Canadian prairies (April 28-May 28, 2019).
Growing season rainfall (April 1 – May 28) amounts have been well below average for most of the prairies, particularly in west central SK and eastern regions of AB (Fig. 6).
Figure 6. Cumulative precipitation observed for the growing season across the Canadian prairies (April 1-May 28, 2019).
Almost all of the prairies has had growing season rainfall amounting to 85 %, or less, than average.
Figure 6. Percent of Average precipitation across the Canadian prairies for the growing season (April 1-May 28, 2019). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (30May2019). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true
Soil moisture values are low across most of the prairies.
Figure 7. Modeled soil moisture (%) across the Canadian prairies (up to May 28, 2019).
The two week forecast is not predicting significant rainfall for the prairies. The Agroclimate National Risk Report for May 7 to May 22, 2019 reports that there is less than a 30% chance of rainfall amounting to >25 mm (May 29-June 4, 2019). The report states that “No rain is expected in the week ahead in areas currently experiencing drought conditions such as southwestern Saskatchewan”.
The growing degree day map (GDD) (Base 5 ºC, April 1-May 27, 2019) is below (Fig. 9):
Figure 9. Growing degree day (Base 5 ºC) across the Canadian prairies for the growing season (April 1-May 27, 2019). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (30May2019). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true
The growing degree day map (GDD) (Base 10 ºC, April 1-May 15, 2019) is below (Fig. 10):
Figure 10. Growing degree day (Base 10 ºC) across the Canadian prairies for the growing season (April 1-May 27, 2019). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (30May2019). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true
The lowest temperatures (°C) observed the past seven days range from -6 to 6 °C in the map below (Fig. 11).
Figure 11. Lowest temperatures (°C) observed across the Canadian prairies the past seven days (May 23-29, 2019). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (30May2019). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true
The highest temperatures (°C) observed the past seven days range from 14 to at least 32 °C in the map below (Fig. 12).
Figure 12. Highest temperatures (°C) observed across the Canadian prairies the past seven days (May 23-29, 2019). Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (30May2019). Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true
The maps above are all produced by Agriculture and Agri-Food Canada. Growers can bookmark the AAFC Drought Watch Maps for the growing season.
Active Wildfires – Natural Resources Canada posts live interactive maps like the one below (Fig. 1). Access their webpage for more information and to stay current on the various active wildfires burning across Canada.
Agriculture and Agri-Food Canada (AAFC) and Environment and Climate Change Canada (ECCC) have been working together to study the potential of trajectories for monitoring insect movements since the late 1990s.
In a continuing effort to produce timely information, the wind trajectory reports are available in two forms:
DAILY REPORTS, as they can be generated, are accessible as a downloadable PDF file on this page.
The Prairie Crop Disease Monitoring Network (PCDMN) represents the combined effort of our prairie pathologists who work together to support in-field disease management in field crops.
In 2019, the PCDMN will release a series of weekly Cereal Rust Risk Reports throughout May and June. Information related to trajectory events based on forecast and diagnostic wind fields and cereal rust risk is experimental, and is OFFERED TO THE PUBLIC FOR INFORMATIONAL PURPOSES ONLY.
Background: Agriculture and AgriFood Canada (AAFC) and Environment and Climate Change Canada (ECCC) have been working together to study the potential of trajectories for monitoring insect movements since the late 1990s. Trajectory models are used to deliver an early-warning system for the origin and destination of migratory invasive species, such as diamondback moth. In addition, plant pathologists have shown that trajectories can assist with the prediction of plant disease infestations and are also beginning to utilize these same data. An introduction will be presented of efforts to identify wind trajectory events that may bring rust urediniospores into Western Canada from epidemic areas in the central and Pacific northwest (PNW) regions of the USA. Identification of potential events as well as an assessment of epidemic severity from source locations, and prairie weather conditions, will be used to assess the need for prompt targeted crop scouting for at-risk regions of the Canadian Prairies.
This week, two documents are available from the PCDMN:
Synopsis of May 21-27, 2019, Weekly Cereal Rust Risk Report:
1. Pacific Northwest – Given limited stripe rust development in the PNW, a low number of recent wind trajectories from the PNW, cool and relatively dry Prairie weather conditions, and generally early stages of Prairie crop development, as of May 27, 2019, the risk of stripe rust appearance from the PNW is limited and scouting for this disease is not urgent.
2. Texas-Oklahoma corridor – Although leaf and stripe rust development continues in this corridor, especially Oklahoma, the disease is mainly affecting the lower canopy at generally low levels. In addition, crops are advancing towards maturity and thus will become less of a source of rust inoculum. There have been a low number of recent wind trajectories from this area, cool and relatively dry Prairie weather conditions, and generally early stages of Prairie crop development. Thus, as of May 27, 2019 the risk of leaf and stripe rust appearance from the Texas-Oklahoma corridor is low and scouting for these diseases is not urgent.
3. Kansas-Nebraska corridor – Although leaf and stripe rust development continues in Kansas, it is at low-moderate levels and mainly in the middle portions of crop canopies. There have been a low-moderate number of recent wind trajectories from this area, cool and relatively dry Prairie weather conditions, and generally early stages of Prairie crop development. Thus, as of May 27, 2019 the risk of leaf and stripe rust appearance from the Kansas-Nebraska corridor is low and scouting for these diseases is not urgent, but further development of rust in these regions may increase the risk.
4. Where farmers or consultants noticed stripe rust development on winter wheat in the fall of 2018, it is recommended to scout winter wheat fields that have resumed growth this spring. Scouting is especially critical where the variety being grown is susceptible to stripe rust. Currently, there are no early spring reports of stripe rust on winter wheat.
Grasshopper Simulation Model Output – The grasshopper simulation model will be used to monitor grasshopper development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of grasshopper development stages based on biological parameters for Melanoplus sanguinipes (Migratory grasshopper).
As of May 28, 2019, predicted grasshopper egg development was 72% (66% last week) and is similar to long term average values (75%) (Fig. 1). Across the prairies, the grasshopper hatch is just beginning with most locations having less than 5% hatch.
Figure 1. Predicted grasshopper (Melanoplus sanguinipes) embryological development across the Canadian prairies as of May 28, 2019. Figure 2. Predicted percent of grasshopper (Melanoplus sanguinipes) population at first instar stage across the Canadian prairies (as of May 28, 2019).
Model runs for Grande Prairie (Fig. 3), Lethbridge (Fig. 4) and Saskatoon (Fig. 5) were projected to June 15, 2019. Results for Lethbridge and Saskatoon indicated that second instars will begin to appear next week. Hatch in near Grande Prairie is predicted to be approximately one week later. Development is predicted to be more advanced in northern areas of the Peace River region.
Figure 3. Predicted status of Melanoplus sanguinipes populations near Grande Prairie AB as of May 28, 2019. Figure 4. Predicted status of Melanoplus sanguinipes populations near Lethbridge AB as of May 28, 2019. Figure 5. Predicted status of Melanoplus sanguinipes populations near Saskatoon SK as of May 28, 2019.
This week we surveyed roadsides south of Saskatoon. Though counts were low, melanoplines were primarily first with a few second instars. Slant faced grasshoppers were most abundant, particularly Aeropedellus clavatus.
Pea Leaf Weevil (Sitona lineatus) – Model runs for Red Deer AB (Fig. 1) and Swift Current SK (Fig. 2) were projected to June 15, 2019. Results indicated that oviposition should begin early next week. Model predictions, based on long term normal weather data predict that initial hatch near Saskatoon should occur on May 29th.
Figure 1. Projected predicted status of pea leaf weevil populations near Red Deer AB to June 15, 2019 using long term average temperatures. Figure 2. Projected predicted status of pea leaf weevil populations near Swift Current SK to June 15, 2019 using long term average temperatures.
Pea leaf weevils emerge in the spring primarily by flying (at temperatures above 17ºC) or they may walk short distances. Pea leaf weevil movement into peas and faba beans is achieved primarily through flight. Adults are slender, greyish-brown measuring approximately 5 mm in length (Fig. 3, Left).
The pea leaf weevil resembles the sweet clover weevil (Sitona cylindricollis) but the former is distinguished by three light-coloured stripes extending length-wise down thorax and sometimes the abdomen. All species of Sitona, including the pea leaf weevil, have a short snout.
Figure 3. Comparison images and descriptions of four Sitona species adults including pea leaf weevil (Left).
Adults will feed upon the leaf margins and growing points of legume seedlings (alfalfa, clover, dry beans, faba beans, peas) and produce a characteristic, scalloped (notched) edge. Females lay 1000 to 1500 eggs in the soil either near or on developing pea or faba bean plants from May to June.
Biological and monitoring information related to pea leaf weevil in field crops is posted by the province of Alberta and in the PPMN monitoring protocol.
Cereal leaf beetle (Oulema melanopus) – The CLB model was run for Brandon MB (Fig. 1), Lethbridge AB (Fig. 2), Grande Prairie AB (Fig. 3) and projected to June 15, 2019. The cereal leaf beetle model indicates that eggs may begin to hatch later next week in Brandon (Fig. 1) and Lethbridge (Fig. 3). Hatch is predicted to be 4-7 days later in the Peace River region (Fig. 3).
Figure 1. Projected predicted status of cereal leaf beetle populations near Lethbridge AB to June 15, 2019,generated using long term average temperatures. Figure 2. Projected predicted status of cereal leaf beetle populations near Brandon MB to June 15, 2019,generated using long term average temperatures. Figure 3. Projected predicted status of cereal leaf beetle populations near Grande Prairie AB to June 15, 2019, generated using long term average temperatures.
Lifecycle and Damage:
Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 2). 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 2. Adult Oulema melanopus measure 4.4-5.5 mm long (Photo: M. Dolinski).
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. 3). When the larva completes its growth, it drops to the ground and pupates in the soil.
Figure 3. Larval stage of Oulema melanopus with characteristic feeding damage visible on leaf (Photo: M. Dolinski).
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.
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”.
Alfalfa Weevil (Hypera postica) – Degree-day maps of base 9°C are produced using the Harcourt/North Dakota models (Soroka et al. 2015). Models predicting the development of Alfalfa weevil (AAW) across the prairies are updated weekly to help growers time their in-field scouting for second-instar larvae.
Model runs for Brooks AB and Swift Current SK were projected to June 15, 2019. The model runs indicate that second instar AAW should begin to appear over the next few days. Third instar larvae are predicted to occur one week later. The warm weather over the next few days may speed up development.
Figure 1. Projected predicted status of alfalfa weevil populations near Brooks AB to June 15, 2019,using long term average temperatures. Figure 2. Projected predicted status of alfalfa weevil populations near Swift Current SK to June 15, 2019,using long term average temperatures.
The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer”. The green larva featuring a dorsal, white line down the length of its body has a dark brown head capsule and will grow to 9mm long.
Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon). Additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from the “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide” (Philip et al. 2015). The guide is available in both a free English-enhancedor French-enhanced version.
Bertha armyworm (Lepidoptera: Mamestra configurata) – Pupal development is approximately 40%. Average development is 48% (Fig. 1).
Figure 1. Predicted bertha armyworm (Mamestra configurata) pupal development acrossthe Canadian prairies as of May 28, 2019.
In order to determine when adults may emerge, the BAW model was run for Brandon MB (Fig. 2), Saskatoon SK (Fig. 3), Lethbridge AB (Fig. 4) and Edmonton AB (Fig. 5) and projected to June 30, 2019. Model projections indicate that adults will begin to emerge in mid June. Recent heat will advance development of pupae. Traps should be placed in fields when pupal development reaches 80%. Based on model projections, it is advisable that traps be placed in fields on or before June 7.
Figure 2. Predicted development of bertha armyworm populations near Brandon MB projected to June 30, 2019. Figure 3. Predicted development of bertha armyworm populations near Saskatoon SK projected to June 30, 2019. Figure 4. Predicted development of bertha armyworm populations near Lethbridge AB projected to June 30, 2019. Figure 5. Predicted development of bertha armyworm populations near Edmonton AB projected to June 30, 2019.
This week, Alberta Agriculture & Forestry’s Scott Meers noted painted lady butterfly larvae (Vanessa cardui). The larvae are important to scout for because this species feeds on a wide range of host plants including soybean (Action threshold=>25% defoliation), sunflowers, borage and dry beans in addition to several species of thistles (including Canada thistle) and mallow.
• Alberta Agriculture and Forestry’s Call of the Land regularly includes insect pest updates from Mr. Scott Meers. The most recent Call of the Land was posted March 18-22, 2019 but did not include an insect update.
Japanese beetle (Popillia japonica) adults CC-BY 2.0 – C. Watts
The Japanese beetle (Popillia japonica) is an invasive pest that has been making steady inroads from the east since being first discovered in North America in 1916 (New Jersey) and in Canada in 1939 (Nova Scotia, Quebec). It has not reached the Prairies yet, but it is found in southern Ontario, Quebec, New Brunswick, Prince Edward Island and Nova Scotia. It has been detected in Vancouver,British Columbia and CFIA is leading a coordinated eradication program and has implemented efforts to prevent the pest’s spread outside Vancouver. The rest of British Columbia is still considered free of Japanese Beetle. In the USA, Minnesota and to the south and east is infested and North Dakota and south is partially infested. Montana and several other western USA states have implemented quarantine and phytosanitary regulations to protect their agriculture sector.
From late June to August, the adult Japanese beetle can attack the leaves and fruit of more than 300 species including ornamentals (birch, elm, maple, mountain ash, rose, zinnia), fruit and vegetables (apple, apricot, asparagus, blueberry, cherry, grape vine, plum, raspberry) and field crops (corn, soybean). The soil-dwelling larvae feed on roots of many species but prefer grass roots, damaging lawns, turf farms, golf courses and pastures.
The adult beetle is oval: 10-12 millimeters (0.5 inches) long by half as wide. It is metallic green with a brown head and metallic bronze wing coverings (elytra). Twelve white hair tufts are arranged along the outside edge of the back-half of the abdomen. Larvae are less than 25 millimetres (1 inch) at maturity and are a typical C-shaped white grub with a yellowish-brown head.
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.
The map below reflects the Highest Temperatures occurring over the past 7 days (June 27, 2018) across the prairies and is available from Agriculture and Agri-Food Canada (Fig. 3).
The map below reflects the Lowest Temperatures occurring over the past 7 days (June 21-27, 2018) across the prairies and is available from Agriculture and Agri-Food Canada (Fig. 4).
Grasshopper Simulation Model Output – The grasshopper simulation model will be used to monitor grasshopper development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of grasshopper development stages based on biological parameters for Melanoplus sanguinipes (Migratory grasshopper).
As of June 24, 2018, the warm weather has resulted in rapid grasshopper development for populations near Saskatoon SK. Model output for Saskatoon predicts that hatch is complete and that populations are primarily in the 4th instar stage (Fig. 1). By comparison, last week’s model output indicated that populations should be primarily in the 2nd and 3rd instar stages.
Figure 1. Predicted grasshopper phenology at Saskatoon SK. Values are based on model simulations for April 1 – June 24, 2018.
Grasshopper Scouting Steps:
● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin.
● Starting at one end in either the field or the roadside and walk toward the other end of the 50 m making some disturbance with your feet to encourage any grasshoppers to jump.
● Grasshoppers that jump/fly through the field of view within a one meter width in front of the observer are counted.
● A meter stick can be carried as a visual tool to give perspective for a one meter width. However, after a few stops one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance.
● At the end point the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure.
● Compare counts to the following damage levels associated with pest species of grasshoppers:
0-2 per m² – None to very light damage
2-4 per m² – Very light damage
4-8 per m² – Light damage
8-12 per m² – Action threshold in cereals and canola
12-24 per m² – Severe damage
>24 per m² – Very severe damage
* For lentils at flowering and pod stages, >2 per m² will cause yield loss.
* For flax at boll stages, >2 per m² will cause yield loss.
Bertha armyworm (Lepidoptera: Mamestra configurata) – As of June 24, 2018, BAW development continues to be 7-10 days ahead of normal development (Figs. 3 A and B). Pupal development is complete across the prairies (Fig. 1).
Near Saskatoon SK, BAW egg hatch is nearly complete and larvae are present (Fig. 2). Based on Long Term Climate Normal (LTCN) data, larvae generally begin to occur the last few days of June (Fig. 3).
Figure 2. Predicted BAW phenology at Saskatoon SK. Values are based on model simulations for April 1 – June 24, 2018 and B) Long term climate normals.Figure 3. Predicted BAW phenology at Saskatoon SK. Values are based on model simulations for Long Term Climate Normals (LTCN).
Many thanks to those who are checking a bertha armyworm pheromone trap on a weekly basis. Please use the reference photo below kindly shared by Saskatchewan Agriculture to aid your identification and reporting of trap interceptions. Note the kidney-bean white-patterned shape on each forewing but also know other cutworm species can resemble bertha armyworm moths. Check carefully and thanks for your help!
Monitoring:
Larval sampling should commence once the adult moths are noted.
Sample at least three locations, a minimum of 50 m apart.
At each location, mark an area of 1 m2 and beat the plants growing within that area to dislodge the larvae.
Count them and compare the average against the values in the economic threshold table below:
Scouting tips:
Some bertha armyworm larvae remain green or pale brown throughout their larval life.
Large larvae may drop off the plants and curl up when disturbed, a defensive behavior typical of cutworms and armyworms.
Young larvae chew irregular holes in leaves, but normally cause little damage. The fifth and sixth instar stages cause the most damage by defoliation and seed pod consumption. Crop losses due to pod feeding will be most severe if there are few leaves.
Larvae eat the outer green layer of the stems and pods exposing the white tissue.
At maturity, in late summer or early fall, larvae burrow into the ground and form pupae.
Keep track of the Provincial Entomologist Updates for the latest in-season pheromone trap monitoring results for 2018.
Albertans can access the online reporting map (screenshot retrieved 28Jun2018 provided below for reference:
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.
Lygus bugs (Lygus spp.) – As of June 24, 2018, the Lygus model suggests that Saskatoon populations should consist of mostly 4th instar nymphs (Fig. 1). Predicted development for the 2018 growing season is greater than for development that is based on long term climate normals (Fig. 2).
Figure 1. Predicted Lygus phenology at Saskatoon SK. Values are based on model simulations for April 1 – June 24, 2018.Figure 2. Predicted Lygus phenology at Saskatoon SK. Values are based on model simulations for Long Term Climate Normals.
Remember – The economic threshold for Lygus in canola is applied at late flower and early pod stages.
Adult L. lineolaris (5-6 mm long) (photo: AAFC-Saskatoon).
Fifth instar lygus bug nymph (3-4 mm long) (photo: AAFC-Saskatoon).
Damage: Lygus bugs have piercing-sucking mouthparts and physically damage the plant by puncturing the tissue and sucking plant juices. The plants also react to the toxic saliva that the insects inject when they feed. Lygus bug infestations can cause alfalfa to have short stem internodes, excessive branching, and small, distorted leaves. They feed on buds and blossoms and cause them to drop. They also puncture seed pods and feed on the developing seeds causing them to turn brown and shrivel.
Begin monitoring canola when it bolts and continue until seeds within the pods are firm. Since adults can move into canola from alfalfa, check lygus bug numbers in canola when nearby alfalfa crops are cut.
Sample the crop for lygus bugs on a sunny day when the temperature is above 20°C and the crop canopy is dry. With a standard insect net (38 cm diameter), take ten 180° sweeps. Count the number of lygus bugs in the net.
Repeat the sampling in another 14 locations. Samples can be taken along or near the field margins. Calculate the cumulative total number of lygus bugs and then consult the sequential sampling chart (Figure C). If the total number is below the lower threshold line, no treatment is needed. If the total is below the upper threshold line, take more samples. If the total is on or above the upper threshold line, calculate the average number of lygus bugs per 10-sweep sample and consult the economic threshold table.
Sequential sampling for lygus bugs at late flowering stage in canola.
The economic threshold for lygus bugs in canola covers the end of the flowering (Table 1) and the early pod ripening stages (Table 2). Once the seeds have ripened to yellow or brown, the cost of controlling lygus bugs may exceed the damage they will cause prior to harvest, so insecticide application is not warranted.
Consider the estimated cost of spraying and expected return prior to making a decision to treat a crop.
Remember that insecticide applications at bud stage in canola have not been proven to result in an economic benefit in production. The exception to this is in the Peace River region where early, dry springs and unusually high densities of lygus bug adults can occasionally occur at bud stage. In this situation, high numbers of lygus bugs feeding on moisture-stressed canola at bud stage is suspected to result in delay of flowering so producers in that region must monitor in fields that fail to flower as expected.
Table 1. Economic thresholds for lygus bugs in canola at late flowering and early pod stages (Wise and Lamb 1998).
1 Canola crop stage estimated using Harper and Berkenkamp 1975). 2 Economic thresholds are based on an assumed loss of 0.1235 bu/ac per lygus bug caught in 10 sweeps (Wise and Lamb. 1998. The Canadian Entomologist. 130: 825-836).
Table 2. Economic thresholds for lygus bugs in canola at pod stage (Wise and Lamb 1998).
3 Economic thresholds are based on an assumed loss of 0.0882 bu/ac per lygus bug caught in 10 sweeps (Wise and Lamb. 1998. The Canadian Entomologist. 130: 825-836).
Biological and monitoring information related to Lygus in field crops is posted by the provinces of Manitoba or Alberta fact sheets or the Prairie Pest Monitoring Network’s monitoring protocol. Also refer to the Lygus pages within the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” – both English-enhanced or French-enhanced versions are available.
Cabbage seedpod weevil (Ceutorhynchus obstrictus) – There is one generation of CSPW per year and the overwintering stage is the adult which is an ash-grey weevil measuring 3-4mm long (Refer to lower left photo). Adults typically overwinter in soil beneath leaf litter within shelter belts and roadside ditches.
Monitoring:
Begin sampling when the crop first enters the bud stage and continue through the flowering.
Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location.
Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field.
Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur.
An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts).
Consider making insecticide applications late in the day to reduce the impact on pollinators. Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators.
High numbers of adults in the fall may indicate the potential for economic infestations the following spring.
Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss. Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo). Eggs are oval and an opaque white, each measuring ~1mm long. Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.
There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo). The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds. A single larva consumes about 5 canola seeds. The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell. Approximately 10 days later, the new adult emerges to feed on maturing canola pods. Later in the season these new adults migrate to overwintering sites beyond the field.
Albertan growers can report and check the online map for CSPW posted by Alberta Agriculture and Forestry (screenshot is provided below for reference; retrieved 28Jun2018).
Pea Leaf Weevil (Sitona lineatus) – As of June 24, 2018, the PLW model predicted that hatch is nearly complete and the population is primarily in the larval stage in the Saskatoon area (Fig. 1). Development in 2018 is faster than long term average (Fig. 2).
Figure 1. Predicted pea leaf weevil phenology at Saskatoon SK. Values are based on model simulations for April 1 – June 24, 2018.Figure 2. Predicted pea leaf weevil phenology at Saskatoon SK. Values are based on model simulations for Long Term Climate Normals (LTCN).
Pea leaf weevil larvae develop under the soil over a period of 30 to 60 days. They are “C” shaped with a dark brown head capsule. The rest of the body is a milky-white color (Fig. 3 A). Larvae develop through five instar stages. In the 5th instar, larvae range in length from 3.5 – 5.5 mm. First instar larvae bury into the soil after hatching, and search out root nodules on field pea and faba bean plants. Larvae enter and consume the microbial contents of the root nodules (Fig. 3 B). These root nodules are responsible for nitrogen-fixation, thus pea leaf weevil larval feeding can affect plant yield and the plant’s ability to input nitrogen into the soil.
Figure 3. Pea leaf weevil larva in soil (A) and field pea root nodules damaged by larval feeding (B). Photos: L. Dosdall).
Biological and monitoring information related to pea leaf weevil in field crops is posted by the province of Alberta and in the PPMN monitoring protocol.
As crops continue to grow, please consider the vital role beneficial organisms have in your fields. Please make use of the Scouting Guides freely available on the Field Heroes website. Each guide includes valuable information and photos to help identify the contents of a sweep-net and to increase understanding of the impact of beneficial insects. Please share and encourage use of the Scouting Guides.
Be sure to follow @FieldHeroes on Twitter for practical tips and information. Please tag @FieldHeroes in your own Tweets about beneficials. Re-Tweets are great, too.
Thanks to Western Grains Research Foundation for their support of this important campaign. This initiative is not possible without the support and advice of enthusiastic members of the Prairie Pest Monitoring Network. Our research is having a tangible impact on growers’ pest management decisions.
Scarabaeidae – Reminder – Each June brings scattered reports across the Prairies of white grubs associated with crop damage. In fact, several species of Aphodius, Phyllophaga, Polyphylla or even small Aetenius produce larvae described as “white grubs”.
Recently, crop damage reports have been associated with a grub identified as the larvae of the beetle Aphodius distinctus (see below). This common beetle is not known to be a pest, but there is an ongoing effort to gather information to develop a ‘pest’ profile. Additional information is online at Top Crop Manager. Please send reports of this insect and associated information to Dr. Kevin Floate (Agriculture and Agri-Food Canada, Lethbridge, AB).
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.
We continue to track the migration of the Monarch butterflies as they move north by checking the 2018 Monarch Migration Map! A screen shot of the map has been placed below as an example (retrieved 28Jun2018) but follow the hyperlink to check the interactive map. They are in Manitoba and moving west through southern Saskatchewan this week!
Visit the Journey North website to learn more about migration events in North America and visit their monarch butterfly website for more information related to this fascinating insect.
West Nile Virus Risk – The regions most advanced in degree-day accumulations for Culex tarsalis, the vector for West Nile Virus, are shown in the map below. Areas highlighted yellow then orange are approaching sufficient heat accumulation for mosquitoes to emerge while mosquitoes will be flying in areas in red so wear DEET to stay protected!
Figure 1. As of surveillance week 49, ending December 9, 2017, the preliminary data indicated 197 human cases of WNV in Canada; twenty-five from Québec, 159 from Ontario, five from Manitoba, seven from Alberta, and one from British Columbia.
The Canadian Wildlife Health Cooperative compiles and posts information related to their disease surveillance for West Nile Virus in birds. As of June 28, 2018, 642 birds were examined and zero have tested positive for West Nile virus.
Provincial entomologists provide insect pest updates throughout the growing season so we link to their most recent information:
Manitoba‘s Insect and Disease Update for 2018 is accessed here. Review the most recent update (June 6, 2018) prepared by John Gavloski and Holly Derksen. The insect update notes flea beetles in canola and cutworms with monitoring for alfalfa weevil larvae underway. Diamondback moth trap numbers remain low and bertha armyworm pheromone traps will go up this week.
Alberta Agriculture and Forestry’s Call of the Land regularly includes insect pest updates from Scott Meers. The most recent Call of the Land (posted on June 21, 2018) noting that bertha armyworm moths were detected this first week of pheromone monitoring (check online map), onset of flowering in canola signalling the need for in-field monitoring for cabbage seedpod weevil, continued grasshopper calls from the south and advice to scout now while nymphs are easier to manage, Nutall’s blister beetle transiently showing up in some fields (blister beetle post), and the presence of the beneficial stiletto fly larvae which is a predator within the soil profile and targets wireworm larvae.
This week’s Insect of the Week is a beneficial wasp from the Family Pteromalidae named Macroglenes penetrans. It is an important natural enemy of wheat midge. The wasp is a parasitoid that lives within the wheat midge larva and overwinters within the host. In the spring, the parasitoid larva develops to emerge from the wheat midge cocoon buried in the soil and seeks out wheat midge eggs.
For more information about M. penetrans, see our Insect of the Week page.
Macroglenes penetrans – adult (AAFC)
Follow @FieldHeroes to learn more about Natural Enemies that are working for you for FREE to protect your crops!
Weather synopsis – This past week our average temperatures were cooler than last week, and 2 – 3°C cooler than long term averages for mid-June (Fig. 1). The second map presents the 30-day average temperature (Fig. 2).
Figure 1. Average temperature across the Canadian prairies from June 4-11, 2017.
Figure 2. Average temperature across the Canadian prairies from May 19-June 19, 2017.
Temperature – The seven-day accumulated precipitation was greater than 15 mm with southeast Saskatchewan and southwest Manitoba reporting amounts in excess of 40 mm (Fig. 3).
Figure 3. Accumulated precipitation across the Canadian prairies from June 11-18, 2017.
Compared to last week, the 30-day rainfall amounts are similar to long term average values for southern Manitoba, southeast Saskatchewan and southwest Alberta (Fig. 4). A large region in south and central Saskatchewan is reporting well below normal precipitation.
Figure 4. Percent of average precipitation from May 20-June 18, 2017.
The following is the accumulated precipitation for the growing season up to June 18, 2017.
The updated growing degree day map (GDD) (Base 5ºC, March 1 – June 18, 2017) is below:
While the growing degree day map (GDD) (Base 10ºC, March 1 – June 18, 2017) is below:
The maps above are all produced by Agriculture and Agri-Food Canada. Growers may wish to bookmark the AAFC Drought Watch Maps for the growing season.
Alfalfa Weevil (Hypera postica) – The model output for alfalfa weevil is not signficantly different that that posted last week for June 22nd (Week 7).
Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon) and additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from the “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide” (Philip et al. 2015). That guide is available in both a free English-enhancedor French-enhanced version.
Grasshopper Simulation Model Output – Predicted hatch was 71% (52% last week) with 30% of the population in the first instar, 26% second instar, 12% third instar and 2% in the fourth instar. Across the prairies, the mean developmental stage was second instar. The greatest development was predicted to be across southern regions in all three provinces.
Grasshopper populations near Saskatoon were predicted to be primarily in the second instar this week with the appearance of third and fourth instars. Model output suggests that grasshopper development is slightly ahead of average development. Based on long term meteorological data, populations should be predominantly in the first and second instars with a low number being third instars. This week’s survey (SW of Saskatoon) indicates that most melanopline grasshoppers are already in the second and third numbers.
Grasshopper Scouting Steps:
● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin.
● Starting at one end in either the field or the roadside and walk toward the other end of the 50 m making some disturbance with your feet to encourage any grasshoppers to jump.
● Grasshoppers that jump/fly through the field of view within a one meter width in front of the observer are counted.
● A meter stick can be carried as a visual tool to give perspective for a one meter width. However, after a few stops one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance.
● At the end point the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure. ● Compare counts to the following damage levels associated with pest species of grasshopers:
0-2 per m² – None to very light damage
2-4 per m² – Very light damage
4-8 per m² – Light damage
8-12 per m² – Action threshold in cereals and canola
12-24 per m² – Severe damage
>24 per m² – Very severe damage
* For lentils at flowering and pod stages, >2 per m² will cause yield loss.
* For flax at boll stages, >2 per m² will cause yield loss.
Bertha armyworm (Lepidoptera: Mamestra configurata) – Bertha armyworm should be in the adult stage across the prairies this week. The map illustrates predicted appearance of adults (percent of the population) across the southern prairies.
For those monitoring BAW pheromone traps, compare trap “catches” to the following reference photo kindly shared by Saskatchewan Agriculture:
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.
Cabbage seedpod weevil (Ceutorhynchus obstrictus) – There is one generation of CSPW per year and the overwintering stage is the adult which is an ash-grey weevil measuring 3-4mm long (Refer to lower left photo). Adults typically overwinter in soil beneath leaf litter within shelter belts and roadside ditches.
Monitoring: ● Begin sampling when the crop first enters the bud stage and continue through the flowering. ● Sweep-net samples should be taken at ten locations within the field with ten 180° sweeps per location. ● Count the number of weevils at each location. Samples should be taken in the field perimeter as well as throughout the field. ● Adults will invade fields from the margins and if infestations are high in the borders, application of an insecticide to the field margins may be effective in reducing the population to levels below which economic injury will occur. ● An insecticide application is recommended when three to four weevils per sweep are collected and has been shown to be the most effective when canola is in the 10 to 20% bloom stage (2-4 days after flowering starts). ● Consider making insecticide applications late in the day to reduce the impact on pollinators. Whenever possible, provide advanced warning of intended insecticide applications to commercial beekeepers operating in the vicinity to help protect foraging pollinators. ● High numbers of adults in the fall may indicate the potential for economic infestations the following spring.
Damage: Adult feeding damage to buds is more evident in dry years when canola is unable to compensate for bud loss. Adults mate following a pollen meal then the female will deposit a single egg through the wall of a developing pod or adjacent to a developing seed within the pod (refer to lower right photo). Eggs are oval and an opaque white, each measuring ~1mm long. Typically a single egg is laid per pod although, when CSPW densities are high, two or more eggs may be laid per pod.
There are four larval instar stages of the CSPW and each stage is white and grub-like in appearance ranging up to 5-6mm in length (refer to lower left photo). The first instar larva feeds on the cuticle on the outside of the pod while the second instar larva bores into the pod, feeding on the developing seeds. A single larva consumes about 5 canola seeds. The mature larva chews a small, circular exit hole from which it drops to the soil surface and pupation takes place in the soil within an earthen cell. Approximately 10 days later, the new adult emerges to feed on maturing canola pods. Later in the season these new adults migrate to overwintering sites beyond the field.
Nysius niger(Lygaeidae) – Agrologists in Saskatchewan have been querying a greyish-black bug spotted this week in some fields of canola, soybeans and flax. Photos and descriptions suggest Nysius niger, an ~4mm long lygaeid, is being observed (Fig. 1 and 2). Reports of damage in canola have been matched with observations of these insects active on plants growing in good conditions with no apparent damage. Reports of damage in canola and flax indicate the bugs are feeding on the main stem near the soil surface.
Growers should be cautious – there is no data confirming whether or not Nysius niger is a pest causing consistent levels of economic damage. Insects can feed on field crop species yet never inflict measurable levels of damage and are therefore not worth managing. Careful scouting is warranted to assess how these insects are feeding AND if damage is occurring and to what extent. Also remember our @FieldHeroes who benefit from less insecticide use and instead reserve insecticide use for economically important pests that cause well-researched levels of damage.
Figure 1. Nysius niger adult on the soil surface in a canola field in Saskatchewan photographed by J. Bogden.
Figure 2. Lygaeid nymphs observed in the above canola field photographed by J. Bogden.
Scarabaeidae – Reminder – Each June brings scattered reports across the Prairies of white grubs associated with crop damage. In fact, several species of Aphodius, Phyllophaga, Polyphylla or even small Aetenius produce larvae described as “white grubs”.
Recently, crop damage reports have been associated with a grub identified as the larvae of the beetle Aphodius distinctus (see below). This common beetle is not known to be a pest, but there is an ongoing effort to gather information to develop a ‘pest’ profile. Additional information is online at Top Crop Manager. Please send reports of this insect and associated information to Dr. Kevin Floate (Agriculture and Agri-Food Canada, Lethbridge, AB).
@Field Heroes – Western Grains Research Foundation is supporting a new initiative to help growers, agrologists and the general public learn more about beneficial arthropods active in field crops. Provincial entomologists from Manitoba, Alberta, and Saskatchewan, along with input from AAFC researchers, are working with Synthesis, a communications company, to promote and increase awareness of these incredible arthropod heroes! Follow @FieldHeroes for great information on these beneficials.
NEW – Access great information on beneficials to support in-field monitoring at http://www.fieldheroes.ca/
The website includes scouting guides to help identify and link pest/beneficial combinations – all aimed at helping growers and agrologists understand and preserve the many arthropods hard at work in fields across the Canadian prairies.
Provincial entomologists provide insect pest updates throughout the growing season so we have attempted to link to their most recent information:
● Manitoba’s Insect and Disease Update for 2017 is prepared by John Gavloski and Pratisara Bajracharya and read Issue #5 (June 21, 2017) noting alfalfa weevil and lingering cutworm issues in that province.
● Saskatchewan’s Crop Production News – 2017 – Issue #2 prepared by Scott Hartley and Danielle Stephens is now posted. It includes updates on how to scout for pea leaf weevil and aster yellows that can occur in all crops. Additionally, very low DBM numbers have been intercepted in pheromone traps deployed throughout Saskatchewan (e.g., seasonal cumulative totals of 10-14 moths per trap were reported “peaks”.
● Watch for Alberta Agriculture and Forestry’s Call of the Land and access the most recent Insect Update (June 22, 2017) provided by Scott Meers. That report notes cabbage seedpod weevil scouting has begun in southern Alberta, isolated reports of red turnip beetle in a few fields in east-central Alberta, the appearance of early instar grasshoppers (1-3 instar stages) west of Edmonton and in the Peace River region despite the weather, and low pea aphid numbers so far in southern Alberta.
We again track the migration of the Monarch butterflies as they move north by checking the 2017 Monarch Migration Map! A screen shot of the map has been placed below as an example (retrieved 22Jun2017) but follow the hyperlink to check the interactive map! They’ve migrated into southern Manitoba and into southeast Saskatchewan!
Across the prairies, weather conditions were warmer and wetter than long term average values for the period of June 6-13, 2016. The average temperature was 15°C and was approximately 2°C warmer than the previous week.
Across the prairies, weather conditions were very similar to long term average (LTN) values for the period of June 13-19, 2016. The average temperature was 14 °C and was approximately 1 °C warmer than the previous week. Temperatures in southern MB were 5-6 °C warmer than many locations in AB.
The Peace River region was wetter than normal while most of southern AB and MB were dryer than normal.
Soil moisture conditions are wettest in the Peace River region and across southern SK and MB. Southern AB and central SK have the driest soil moisture conditions.
The map below reflects the Accumulated Precipitation for the Growing Season so far for the prairie provinces (i.e., April 1-June 20, 2016):
Compared to last week, overnight temperatures were warmer during the past 7 days. The map below shows the Lowest Temperatures the Past 7 Days (June 14-20, 2016) across the prairies:
The map below shows the Highest Temperatures the Past 7 Days (June 14-20, 2016):
The updated growing degree day map (GDD) (Base 5ºC, March 1 – June 19, 2016) is below:
While the growing degree day map (GDD) (Base 10ºC, March 1 – June 19, 2015) is below:
The maps above are all produced by Agriculture and Agri-Food Canada. Growers may wish to bookmark the AAFC Drought Watch Maps for the growing season.
Cutworms (Noctuidae) – Please refer to earlier cutworm posts describing scouting tips, monitoring protocols and fact sheets (including cutworm images plus action and economic thresholds).
For Manitobans….The earlier Insect Update included great photos of dingy and redbacked cutworms plus monitoring tips including how to discern these two species from one another. Reports of cutworm continued in the current Insect Update. For Saskatchewanians…. Cutworms were reported in the recent Saskatchewan Insect Report (Issue 3). For Albertans….. Additional reports of cutworms have occurred throughout the province the past week! If you find cutworms, please consider using the Alberta Pest Surveillance Network’s “2016 Cutworm Reporting Tool”. Once data entry occurs, your growers can view the live 2016 cutworm map.
A screen shot of the live map has been retrieved (22Jun2016) below for your reference.
Bertha armyworm (Lepidoptera: Mamestra configurata) – Moths should have appeared in pheromone traps by now since all areas of arable prairie farmland are highlighted either yellow or orange in the map below.
Those monitoring BAW pheromone traps may want to compare trap “catches” to the following reference photo kindly shared by Saskatchewan Agriculture below:
Provincial staff coordinate BAW pheromone trapping across the prairies and summarize cumulative counts in report or map formats:
● Saskatchewanians.… Watch for future Insect Reports. ● Manitobans.…. Exceedingly low numbers of male moths were intercepted during the first week of monitoring (Insect and Disease Report posted June 15, 2016, prepared by J. Gavloski).
Grasshoppers (Acrididae) – Previous model predictions related to hatch and nymphal instar development can be reviewed here.
For the week of June 19, 2016, warm conditions in southeastern Saskatchewan and southern Manitoba were predicted to result in enhanced grasshopper development. Across the prairies, grasshoppers should be between the first and fifth instars. The model predicted that approximately 15% of the population was predicted to be in the first instar, 35% second, 28% third, 13% fourth instar and just under one percent fifth instar. Development is well ahead of average rates (22% first instar, 14% second instar and 10% third instar).
In central Saskatchewan, grasshopper development is currently more than two weeks ahead of average development. The following graph shows grasshopper development at Saskatoon based on 2016 data. The model indicates that fifth instar grasshoppers should be present.
Now compare the above with the following graph which illustrates grasshopper development (for Saskatoon) based on long term normal (LTN) data. The model indicates that primarily first instars are predicted to be present with only the initial appearance of third instar nymphs.
The following image showing various stages of the clearwinged grasshopper is provided below – note that adults have wings extending the length of the abdomen whereas nymphs lack wings but develop wing buds that will eventually mature to wings.
Figure 1. Life stages of Camnulla pellucida which including eggs, first-fifth instar nymphs and adult (L-R).
