Scouting for canola flower midge tends to be easiest as the flowering stage of canola ends and pod development begins. Female canola flower midge lay eggs on developing canola buds and larvae develop inside the buds, resulting in galled flowers that do not open or produce pods.
Although canola flower midge does not appear to occur at densities that cause economic damage, scouting for canola flower midge will help to monitor population growth at the local scale to avoid surprises in the future. The monitoring protocol used during our survey from 2017-2019 is now available online so that everyone can scout for canola flower midge.
Check out the Canola Flower Midge Scouting post from Week 10 for pictures of damage caused by this insect and to see a map of canola flower midge distribution.
From the Insect Surveillance Community of Practice:
Do you spend time monitoring, photographing or observing insects? If so, your help is needed to watch for and report invasive and migratory insect pests that harm plants, causing damage to Canada’s environment, farm lands, forests, parks and other natural areas. Early detection is critical for slowing the spread of these insect pests.
View the poster for your region (links below) to learn more about priority insect pests to watch out for. Use the QR codes on the posters to report your detections!
A sample from the Priority Invasive and Migratory Insects to Report poster for the Prairie Region. Use the links below to view and download the full version of the Prairie Region poster, as well as posters for other regions in Canada.
This initiative is a collaborative project developed by the Insect Surveillance Community of Practice of the Canadian Plant Health Council, a multi-partner body that coordinates action for the protection of plant health in Canada.
Scouting for canola flower midge tends to be easiest as the flowering stage of canola ends and pod development begins. Female canola flower midge lay eggs on developing canola buds and larvae develop inside the buds, resulting in galled flowers that do not open or produce pods.
A canola raceme with galled flowers containing canola flower midge larvae; these galled flowers will not produce pods. Picture credit: Boyd Mori, University of Alberta.
From 2017-2019, entomologists and volunteers across the prairies conducted a survey to determine the range of canola flower midge (Fig. 1). There has not been a formal survey conducted since 2019.
Figure 1.Density of canola flower midge, based on the number of galled flowers per raceme across the prairie region observed during a survey conducted in 2017, 2018, and 2019. Map credit: Shane Hladun; map modified from Vankosky et al. (2022).
Although canola flower midge does not appear to occur at densities that cause economic damage, scouting for canola flower midge will help to monitor population growth at the local scale to avoid surprises in the future. The monitoring protocol used from 2017-2019 is now available online so that everyone can scout for canola flower midge.
*If you cannot follow the link to the protocol, please contact Dr. Meghan Vankosky (meghan.vankosky@agr.gc.ca).
May was characterized by wonky weather – unseasonably warm days and very little rain. As a result, some prairie insect pests are developing faster than normal.
Grasshoppers thrive in warm, dry conditions and we continue to hear about high numbers of nymphs along roadsides and field edges. Last week, we also observed some third instar grasshopper nymphs, which normally do not appear in the population until mid-June. Diamondback moths that arrived in early May have likely reproduced and adult moths found now could be from the first generation produced on the prairies. Bertha armyworm development is also well ahead of schedule – pupal development could be 90% complete in some areas, so it is probably time to set up pheromone traps for bertha armyworm monitoring in most parts of the prairies. This week, we featured the pea leaf weevil in the Insect of the Week – the annual damage survey for pea leaf weevil is now underway! For more information, check out the posts in the Weekly Update!
Remember, insect Monitoring Protocols containing helpful insect pest biology, how and when to plan for in-field scouting, and even thresholds to help support in-field management decisions are all available for review or download.
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.
Over the past 5-7 days we have conducted a roadside survey for grasshoppers in west-central Saskatchewan. Numbers and development were higher than normal. First and second instar nymphs were found at all locations and many sites had low numbers of third instar grasshopper nymphs. We generally do not see third instars until mid-June! Many locations had high numbers of first instars suggesting that the hatch is still progressing. Melanoplus bivittatus, the two-striped grasshopper, was the most common species at all locations sampled in Saskatchewan in the last five days.
Our observations in the field over the last week agree with the model simulation used to estimate the status of grasshopper development as of May 28, 2023. Grasshopper development is progressing rapidly where temperatures have been well above normal in Alberta and western Saskatchewan. Model runs for 2023 suggest that egg development is 87% complete, on average. At the end of May in an average year, we would expect egg development to be only 72% complete. Recent warm conditions across southern Manitoba have also resulted in faster development rates for eggs.
Grasshopper eggs are now hatching across Alberta and in western and central regions of Saskatchewan (Fig. 1). Hatch rates are well ahead of expected hatch rates based on long-term average weather conditions. In central and eastern regions and across most of Manitoba, hatch is predicted to be less than 15% but hatch rate is increasing (15-45%) in southern Manitoba after some warmer weather last week.
Figure 1. Predicted grasshopper (Melanoplus sanguinipes) hatch (%) across the Canadian prairies as of May 28, 2023.
2023 is shaping up to be an interesting year for grasshoppers and prairie farmers should be prepared to scout for grasshoppers, especially if conditions remain warmer and drier than normal. For more information about grasshopper scouting, biology, and management in your province (Alberta, Saskatchewan, Manitoba), please check out their resources available online.
Diamondback moths (Plutella xylostella) are a migratory invasive species to western Canada. 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, resulting in subsequent non-migrant populations that may have three or four generations during the growing season. DBM development can be rapid during periods of warm weather. Model simulations, initiated in early May and extendingto May 28, 2023, indicate that the first generation of non-migrant adults are currently occurring across the Canadian prairies (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 May 28, 2023.
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 dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.
Biological and monitoring information for diamondback moth (including tips for scouting and economic thresholds) is posted by Manitoba Agriculture, Saskatchewan Ministry of Agriculture, and the Prairie Pest Monitoring Network. Also, refer to the diamondback moth pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (2018) accessible as a free downloadable PDF in either English or French on our Field Guides page.
Based on model simulations, development of overwintered bertha armyworm (Mamestra configurata) pupae is rapidly progressing this spring (Fig. 1).
Figure 1. Predicted bertha armyworm (Mamestra configurata) pupal development (% complete) across the Canadian prairies as of May 28, 2023.
In fact, development is significantly ahead of normal for most of the prairies (Figs. 2). Models suggest that bertha armyworm pupal development in Alberta is 10-14 days faster than average development for this time of year. There are small areas in Alberta where the model predicts that pupal development may be greater than 90% completed.
Figure 2. Long-term average predicted bertha armyworm (Mamestra configurata) pupal development (% completion) across the Canadian prairies as of May 28, 2023. Model runs were conducted with climate normals data.
Where bertha armyworm are present, adults may be appearing in areas where predicted pupal development is greater than 90% complete. We suggest that bertha armyworm traps should be installed as soon as possible. Many thanks to all of the volunteers across the Prairie region who are hosting BAW pheromone traps in 2023!
The grasshopper model predicts development of the migratory grasshopper (Melanoplus sanguinipes) and closely related species using biological parameters known for the pest species and environmental data observed across the Canadian prairies on a daily basis. Review lifecycle and damage information for this pest. Review the historical grasshopper maps based on late-summer adult in-field counts performed across the prairies. Results from the 2022 late-summer adult grasshopper survey are shown in Fig. 1.
Figure 1. Adult grasshopper densities in late summer of 2022.
Model simulations were used to estimate development of grasshopper eggs as of May 7, 2023. Compared with average spring temperatures, well above normal temperatures in Alberta and western Saskatchewan thus far this spring are predicted to result in rapid grasshopper egg development (Fig. 2). As a result, grasshopper egg development in 2023 is expected to be advanced as compared to egg development in average growing seasons (Fig. 3). Cool conditions in Manitoba have resulted in slower rates of egg development. Areas with the highest adult grasshopper densities in summer 2022 (Fig. 1) overlap with regions where egg development is predicted to be most advanced so far in spring 2023 (Fig. 2). Based on the 2022 survey, high densities were reported across a large region that extended south of the Yellowhead Highway corridor to the Canada-USA border (Fig. 1).
Prairie farmers should be prepared to scout for grasshoppers in spring and early summer this year, especially if conditions remain warmer and drier than normal.
Figure 2. Predicted grasshopper (Melanoplus sanguinipes) embryological development across the Canadian Prairies as of May 7, 2023.Figure 3. Long-term average predicted grasshopper (Melanoplus sanguinipes) embryological development across the Canadian prairies as of May 7, 2023, based on climate normals data.
Reminder – One last time for this growing season….. We have updated the field scouting charts so they now link to pages within the 2018 version of the Insect Field Guide.
We offer TWO generalized insect pest scouting charts to aid in-field scouting on the Canadian prairies:
Whenever possible, monitor and compare pest densities to established economic or action thresholds to protect and preserve pollinators and beneficial arthropods. Economic thresholds, by definition, help growers avoid crop losses related to insect pest species but they rely on in-field scouting!
Pea Leaf Weevil (Sitona lineatus) – Model runs for Red Deer and Saskatoon were projected to June 30, 2019. Results indicated that oviposition is well underway at both locations.
Figure 1. Predicted status of pea leaf weevil populations near Red Deer AB projected to June 30, 2019, using long term average temperatures. Figure 2. Predicted status of pea leaf weevil populations near Saskatoon SK projected to June 30, 2019, using long term average temperatures.
This week, pea leaf weevil and its doppelgangers were featured as part of the INSECT OF THE WEEK.
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.
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.
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 at the end of May. 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.
Flea Beetles (Chrysomelidae: Phyllotreta species)– As newly seeded stands begin to emerge, the need for in-field scouting increases. Review Wk05 for flea beetle information, visual guides to help estimate percent of cotyledon damage, and links to the Insect Field Guide.
Remember, the Action Threshold for flea beetles on canola is 25% of cotyledon leaf area consumed. Watch for shot-hole feeding in seedling canola but also watch the growing point and stems of seedlings which are particularly vulnerable to flea beetle feeding.
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 at the end of May. 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.
Whenever possible, monitor and compare pest densities to established economic or action thresholds to protect and preserve pollinators and beneficial arthropods. Economic thresholds, by definition, help growers avoid crop losses related to outbreaking insect pest species.
Flea Beetles (Chrysomelidae: Phyllotreta species)– Reminder – Be on the lookout for flea beetle damage resulting from feeding on canola cotyledons but also on the stem. Two species, Phyllotreta striolata and P. cruciferae, will feed on all cruciferous plants but they can cause economic levels of damage in canola during the seedling stages.
Remember, the Action Threshold for flea beetles on canola is 25% of cotyledon leaf area consumed. Watch for shot-hole feeding in seedling canola but also watch the growing point and stems of seedlings which are particularly vulnerable to flea beetle feeding.
Estimating flea beetle feeding damage can be challenging. Using a visual guide to estimate damage can be helpful. Canola Watch circulated this article but also use the two images (copied below for reference) produced by Dr. J. Soroka (AAFC-Saskatoon) – take it scouting!
Figure 1. Canola cotyledons with various percentages of leaf area consume owing to flea beetle feeding damage (Photo: Soroka & Underwood, AAFC-Saskatoon).
Figure 2. Percent leaf area consumed by flea beetles feeding on canola seedlings (Photo: Soroka & Underwood, AAFC-Saskatoon).
Refer to the flea beetle page from the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” as an English-enhanced or French-enhanced version.
Pea Leaf Weevil (Sitona lineatus) – The PLW model was run for Red Deer AB (Fig. 1) and Saskatoon SK (Fig. 2). The predictive model outputs suggest that PLW adults are active but oviposition has not begun.
Figure 1. Predicted status of pea leaf weevil populations near Red Deer as of May 7, 2019. Figure 2. Predicted status of pea leaf weevil populations near Saskatoon SK as of May 7, 2019.
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.
Flea Beetles (Chrysomelidae: Phyllotreta species) – Be on the lookout for flea beetle damage resulting from feeding on canola cotyledons but also on the stem. Two species, Phyllotreta striolata and P. cruciferae, will feed on all cruciferous plants but they can cause economic levels of damage in canola during the seedling stages.
Remember, the Action Threshold for flea beetles on canola is 25% of cotyledon leaf area consumed. Watch for shot-hole feeding in seedling canola but also watch the growing point and stems of seedlings which are particularly vulnerable to flea beetle feeding.
Estimating flea beetle feeding damage can be challenging. Using a visual guide to estimate damage can be helpful. Canola Watch circulated this article but also use the two images (copied below for reference) produced by Dr. J. Soroka (AAFC-Saskatoon) – take it scouting!
Figure 1. Canola cotyledons with various percentages of leaf area consume owing to flea beetle feeding damage (Photo: Soroka & Underwood, AAFC-Saskatoon).
Figure 2. Percent leaf area consumed by flea beetles feeding on canola seedlings (Photo: Soroka & Underwood, AAFC-Saskatoon).
Refer to the flea beetle page from the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” as an English-enhanced or French-enhanced version.
Pea Leaf Weevil (Sitona lineatus) – The PLW model was run for Red Deer AB (Fig. 1) and Saskatoon SK (Fig. 2). The output suggests that PLW are beginning to become active and will begin to fly on warmer days (Figs. 1 and 2).
Figure 1. Predicted overwintered PLW adults near Red Deer AB as of April 30, 2019. Figure 2. Predicted overwintered PLW adults near Saskatoon SK as of April 30, 2019.
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.
Field scouting is critical – it enables the identification of potential risks to crops. Accurate identification of insect pests PLUS the application of established monitoring methods will enable growers to make informed pest management decisions.
We offer TWO generalized insect pest scouting charts to aid in-field scouting on the Canadian prairies:
Whenever possible, monitor and compare pest densities to established economic or action thresholds to protect and preserve pollinators and beneficial arthropods. Economic thresholds, by definition, help growers avoid crop losses related to outbreaking insect pest species.
Pea Leaf Weevil (Sitona lineatus) – The PLW model was run for Lethbridge AB (Fig. 1) and Saskatoon SK (Fig. 2). Output suggests that PLW are beginning to become active.
Figure 1. Predicted PLW phenology at Lethbridge AB based on long term climate data. Values are based on model simulations (April 1 – April 23, 2019).Figure 2. Predicted PLW phenology at Saskatoon SK based on long term climate data. Values are based on model simulations (April 1 – April 23, 2019).
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.
Reminder – The risk map for pea leaf weevils was released in March 2019. The map is based on the number of feeding notches observed in peas (Fig. 4).
Figure 4. Estimates of pea leaf weevil (S. lineatus) densities based on feeding notches observed in peas grown in Alberta and Saskatchewan in 2018.
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.
Pea Leaf Weevil (Sitona lineatus) – Over the past ten days newly emerged adult pea leaf weevils are predicted to be emerging from pea crops (Fig. 1).
Figure 1. Predicted pea leaf weevil phenology at Saskatoon (A) and Lethbridge (B). Values are based on model simulations for the current growing season (April 1 – July 30, 2018).
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. 2 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. 2 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 2. 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.
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.
Pea Leaf Weevil (Sitona lineatus) – The PLW model predicted that larvae should be appearing in fields near Saskatoon (Fig. 1). Development in 2018 is faster than that predicted using long term averages (LTCN presented in Fig. 2).
Figure 1. Predicted pea leaf weevil phenology at Saskatoon SK. Values are based on model simulations for April 1 – June 18, 2018.Figure 2. Predicted pea leaf weevil phenology at Saskatoon SK. Values are based on model simulations for April 1 – June 18, 2018. using Long Term Climate Normals.
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.
Pea Leaf Weevil (Sitona lineatus) – The PLW model predicts that oviposition is nearly complete and PLW are primarily in the adult and egg stages (Fig. 1). Larvae should begin to appear later this week.
Figure 1. Predicted pea leaf weevil phenology at Red Deer AB. Values are based on model simulations, for April 1-May 28, 2018 (projected to July 15, 2018).
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 (view weevil adult photos here).
Adults 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 (Fig. 4). Females lay 1000 to 1500 eggs in the soil either near or on developing pea or faba bean plants from May to June.
Figure 4. Scalloped notching along leaf margins of pea plant (Photo: L. Dosdall).
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. 5 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. 5 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 5. 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.
Pea Leaf Weevil (Sitona lineatus) – The PLW model predicts that oviposition is occurring across southern and central regions of the prairies (example Red Deer (Fig. 9).
Figure 1. Predicted pea leaf weevil phenology at Red Deer AB. Values are based on model simulations, for April 1-May 28, 2018 (projected to July 15, 2018).
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. 2, 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 2. 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.
Reminder – The 2017 risk map for pea leaf weevils was released in March 2018. The map is based on the number of feeding notches observed in peas (Fig. 3).
Figure 3. Estimates of pea leaf weevil (S. lineatus) densities based on feeding notches observed in peas grown in Alberta and Saskatchewan in 2017.
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.
Flea Beetles (Chrysomelidae: Phyllotreta species) – The Insect of the Week features flea beetles!
Be on the lookout for flea beetle damage resulting from feeding on canola cotyledons but also on the stem. Two species, Phyllotreta striolata and P. cruciferae, will feed on all cruciferous plants but they can cause economic levels of damage in canola during the seedling stages.
Remember, the Action Threshold for flea beetles on canola is 25% of cotyledon leaf area consumed. Watch for shot-hole feeding in seedling canola but also watch the growing point and stems of seedlings which are particularly vulnerable to flea beetle feeding. Estimating flea beetle feeding damage can be challenging. Using a visual guide to estimate damage can be helpful. Canola Watch circulated this article but also use the two images (copied below for reference) produced by Dr. J. Soroka (AAFC-Saskatoon) – take it scouting!
Figure 1. Canola cotyledons with various percentages of leaf area consume owing to flea beetle feeding damage (Photo: Soroka & Underwood, AAFC-Saskatoon).
Figure 2. Percent leaf area consumed by flea beetles feeding on canola seedlings (Photo: Soroka & Underwood, AAFC-Saskatoon).
Refer to the flea beetle page from the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” as an English-enhanced or French-enhanced version.
Pea Leaf Weevil (Sitona lineatus) – The PLW model predicts that oviposition is occurring across southern and central regions of the prairies (example Swift Current – Fig. 1).
Figure 1. Predicted pea leaf weevil phenology at Swift Current SK.
Values are based on model simulations (April 1-May 28, 2018 and projected to July 1, 2018).
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. 2, 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 2. 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. Reminder – The 2017 risk map for pea leaf weevils was released in March 2018. The map is based on the number of feeding notches observed in peas (Fig. 3).
Figure 3. Estimates of pea leaf weevil (S. lineatus) densities based on feeding notches observed in
peas grown in Alberta and Saskatchewan in 2017.
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.
Flea Beetles (Chrysomelidae: Phyllotreta species) – Be on the lookout for flea beetle damage resulting from feeding on canola cotyledons but also on the stem. Two species, Phyllotreta striolata and P. cruciferae, will feed on all cruciferous plants but they can cause economic levels of damage in canola during the seedling stages.
Remember, the Action Threshold for flea beetles on canola is 25% of cotyledon leaf area consumed. Watch for shot-hole feeding in seedling canola but also watch the growing point and stems of seedlings which are particularly vulnerable to flea beetle feeding. Estimating flea beetle feeding damage can be challenging. Using a visual guide to estimate damage can be helpful. Canola Watch circulated this article but also use the two images (copied below for reference) produced by Dr. J. Soroka (AAFC-Saskatoon) – take it scouting!
Figure 1. Canola cotyledons with various percentages of leaf area consume owing to flea beetle feeding damage (Photo: Soroka & Underwood, AAFC-Saskatoon).
Figure 2. Percent leaf area consumed by flea beetles feeding on canola seedlings (Photo: Soroka & Underwood, AAFC-Saskatoon).
Refer to the flea beetle page from the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” as an English-enhanced or French-enhanced version.
Pea Leaf Weevil (Sitona lineatus) – The PLW model predicts that adult weevils should be out and that oviposition may be occurring in fields with emerging peas. An example of PLW predicted phenology for Swift Current SK is presented in Figure 1.
Figure 1. Predicted PLW phenology at Swift Current, SK. Values are based on model simulations,
for April 1 – May 21, 2018 (projected to July 1, 2018).
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. 2, 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 2. 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. Reminder – The 2017 risk map for pea leaf weevils was released in March 2018. The map is based on the number of feeding notches observed in peas (Fig. 3).
Figure 3. Estimates of pea leaf weevil (S. lineatus) densities based on feeding notches observed in
peas grown in Alberta and Saskatchewan in 2017.
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.
Field scouting is critical – it enables the identification of potential risks to crops. Accurate identification of insect pests PLUS the application of established monitoring methods will enable growers to make informed pest management decisions. We offer TWO generalized insect pest scouting charts to aid in-field scouting on the Canadian prairies: 1. CANOLA INSECT SCOUTING CHART 2. A NEW FLAX INSECT SCOUTING CHART These charts feature hyperlinks directing growers to downloadable PDF pages within the “Field crop and forage pests and their natural enemies in western Canada: Identification and management field guide“. Whenever possible, monitor and compare pest densities to established economic or action thresholds to protect and preserve pollinators and beneficial arthropods. Economic thresholds, by definition, help growers avoid crop losses related to outbreaking insect pest species. Good luck with your scouting!
Field scouting is critical – it enables the identification of potential risks to crops. Accurate identification of insect pests PLUS the application of established monitoring methods will enable growers to make informed pest management decisions. We offer TWO generalized insect pest scouting charts to aid in-field scouting on the Canadian prairies: 1. CANOLA INSECT SCOUTING CHART 2. A NEW FLAX INSECT SCOUTING CHART These charts feature hyperlinks directing growers to downloadable PDF pages within the “Field crop and forage pests and their natural enemies in western Canada: Identification and management field guide“. Whenever possible, monitor and compare pest densities to established economic or action thresholds to protect and preserve pollinators and beneficial arthropods. Economic thresholds, by definition, help growers avoid crop losses related to outbreaking insect pest species. Good luck with your scouting!
Flea Beetles (Chrysomelidae: Phyllotreta species) – Be on the lookout for flea beetle damage resulting from feeding on canola cotyledons but also on the stem. Two species, Phyllotreta striolata and P. cruciferae, will feed on all cruciferous plants but they can cause economic levels of damage in canola during the seedling stages.
Remember, the Action Threshold for flea beetles on canola is 25% of cotyledon leaf area consumed. Watch for shot-hole feeding in seedling canola but also watch the growing point and stems of seedlings which are particularly vulnerable to flea beetle feeding. Estimating flea beetle feeding damage can be challenging. Using a visual guide to estimate damage can be helpful. Canola Watch circulated this article but also use the two images (copied below for reference) produced by Dr. J. Soroka (AAFC-Saskatoon) – take it scouting!
Figure 1. Canola cotyledons with various percentages of leaf area consume owing to flea beetle feeding damage (Photo: Soroka & Underwood, AAFC-Saskatoon).
Figure 2. Percent leaf area consumed by flea beetles feeding on canola seedlings (Photo: Soroka & Underwood, AAFC-Saskatoon).
Refer to the flea beetle page from the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” as an English-enhanced or French-enhanced version.
Pea Leaf Weevil (Sitona lineatus) – The PLW model predicts that adults are beginning to fly. This is similar to model output based on long term (climate) data. Model output estimates that oviposition should begin in late May or early June (Fig. 1).
Figure 1. Predicted PLW phenology at Swift Current based on long term climate data.
Values are based on model simulations (April 1 – May 6).
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. 2, 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 2. 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.
Reminder – The 2017 risk map for pea leaf weevils was released in March 2018. The map is based on the number of feeding notches observed in peas (Fig. 3).
Figure 3. Estimates of pea leaf weevil (S. lineatus) densities based on feeding notches observed in
peas grown in Alberta and Saskatchewan in 2017.
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.
Flea Beetles (Chrysomelidae: Phyllotreta species) – Be on the lookout for flea beetle damage resulting from feeding on canola cotyledons but also on the stem. Two species, Phyllotreta striolata and P. cruciferae, will feed on all cruciferous plants but they can cause economic levels of damage in canola during the seedling stages.
Remember, the Action Threshold for flea beetles on canola is 25% of cotyledon leaf area consumed. Watch for shot-hole feeding in seedling canola but also watch the growing point and stems of seedlings which are particularly vulnerable to flea beetle feeding. Estimating flea beetle feeding damage can be challenging. Using a visual guide to estimate damage can be helpful. Canola Watch circulated this article but also use the two images (copied below for reference) produced by Dr. J. Soroka (AAFC-Saskatoon) – take it scouting!
Figure 1. Canola cotyledons with various percentages of leaf area consume owing to flea beetle feeding damage (Photo: Soroka & Underwood, AAFC-Saskatoon).
Figure 2. Percent leaf area consumed by flea beetles feeding on canola seedlings (Photo: Soroka & Underwood, AAFC-Saskatoon).
Refer to the flea beetle page from the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” as an English-enhanced or French-enhanced version.
Pea Leaf Weevil (Sitona lineatus) – The PLW model predicts that adults are emerging from overwintering sites and beginning to fly. This is similar to model output based on long term (climate) data. Looking forward, based on long term average climate data, oviposition should occur in late May or early June (Fig. 1).
Figure 1. Predicted PLW phenology at Swift Current based on long term climate data. Values are
based on model simulations (April 1 – May 6).
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. 1, 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 1. 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.
Field scouting is critical – it enables the identification of potential risks to crops. Accurate identification of insect pests PLUS the application of established monitoring methods will enable growers to make informed pest management decisions. We offer TWO generalized insect pest scouting charts to aid in-field scouting on the Canadian prairies: 1. CANOLA INSECT SCOUTING CHART 2. A NEW FLAX INSECT SCOUTING CHART These charts feature hyperlinks directing growers to downloadable PDF pages within the “Field crop and forage pests and their natural enemies in western Canada: Identification and management field guide“. Whenever possible, monitor and compare pest densities to established economic or action thresholds to protect and preserve pollinators and beneficial arthropods. Economic thresholds, by definition, help growers avoid crop losses related to outbreaking insect pest species. Good luck with your scouting!
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:
Alfalfa Weevil (Hypera postica) – Across the prairies, the model indicates that 95% of the population should be in the pupal stage. This week adults should be appearing at most locations. Output indicates that adult emergence is well underway at many southern locations (Brooks, Estevan) , while adult emergence at many central locations (Saskatoon) has begun over the last five days.
In terms of degree-day heat units, the map below reflects the predicted development of alfalfa weevil across the Canadian prairies.
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.
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:
Alfalfa Weevil (Hypera postica) – Across the prairies, the model indicates that 80% of the population should be in the pupal stage. Adults should be appearing near Saskatoon this week.
In terms of degree-day heat units, the map below reflects the predicted development of alfalfa weevil across the Canadian prairies.
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.
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:
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.
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:
Grasshopper Simulation Model Output – Simulation modelling is used to predict grasshopper development across the prairies. Weekly temperature data is incorporated into the model which calculates estimates of grasshopper development stages based on biological parameters for Melanoplus sanguinipes (Migratory grasshopper). Predicted hatch for June 11, 2017, was 52% (23% last week) with 32% of the population in the first instar, 15% second instar and 15% third instar.
The greatest development was predicted to be across southern regions in all three provinces, particularly southeastern Alberta and a region extending south from Swift Current/Regina to the US border.
Grasshopper populations near Saskatoon were predicted to be primarily in the second instar with appearance of some third and fourth instars. This week’s survey (southwest of Saskatoon) agreed with model predictions with first collections of a few fourth instars.
Model output for Grande Prairie indicates that development continues to be approximately 10 days later than locations across the southern prairies.
Bertha armyworm (Lepidoptera: Mamestra configurata) – Emergence of adult moths is well underway. The map illustrates predicted appearance of adults (percent of the population) across the southern prairies; oviposition is predicted to begin this week with first hatch beginning later next week.
For those of you monitoring BAW pheromone traps, you may want to compare trap “catches” to the following reference photo kindly shared by Saskatchewan Agriculture:
Pea Leaf Weevil (Sitona lineatus) – Oviposition is predicted to have peaked across central and southern regions of Alberta and Saskatchewan. Hatch should be underway in pea fields near Lethbridge while hatching is predicted to occur this week near Saskatoon.
Alfalfa Weevil (Hypera postica) – Recent warm weather has resulted in rapid alfalfa weevil development. Model output indicates that 98% of the hatch is complete (less than 80% last week). Larval populations should be predominantly in the second (35%) and third (46%) instars.
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.
Cereal leaf beetle (Oulema melanopus) – As of June 5, 2017, model output indicates that oviposition should be nearly complete and larval populations should peak across the southern prairies.
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 (~4.4-5.5 mm long).
Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the mid vein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching. Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 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.
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) – Reminder – Biological information and photos of all life stages of this insect can reviewed on the Week 4 post. The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer”. Degree-day maps of base 9°C are now being produced by Soroka, Olfert, and Giffen (2016) using the Harcourt/North Dakota models. Models predicting the development of Alfalfa weevil across the prairies are updated weekly to help growers time their in-field scouting for second-instar larvae. Compare the following predicted development stages and degree-day values from Soroka (2015) to the map below.
As of June 4, 2017, the recent warm weather has resulted in rapid development, indicating that 80% of the hatch is probably complete (less than 20% last week). Larval populations should be predominantly in the first and second instars (less than 10% are predicted to be third instars).
Figure 1. Heat units accumulated necessary for the development of Alfalfa weevil (Hypera postica) across the Canadian prairies (April 1-June 4, 2017).
Remember – Use the photo below as a visual reference to identify alfalfa weevil larvae. Note the white dorsal line, the tapered shape of the abdomen and the dark head capsule.
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.
Pea Leaf Weevil (Sitona lineatus) – This week, weevil oviposition is predicted to be occurring across central and southern regions of Alberta and Saskatchewan.
The PLW Blitz continues this week and features: – The Insect of the Week from June 1st, – ANEWLY UPDATED Monitoring Protocol (Vankosky et al. 2017), AND – The current Insect of the Week features a group of beetles recognized as general predators but one species is an egg predator associated with Pea leaf weevil.
Remember – 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 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 (Fig. 4). Females lay 1000 to 1500 eggs in the soil either near or on developing pea or faba bean plants from May to June.
Figure 4. Scalloped notching along leaf margins of pea plant (Photo: L. Dosdall).
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 5, 2017, model output suggests that most of the population is still at the egg stage. However, recent warm conditions have advanced grasshopper development. Predicted hatch was 23% (17% first instar and 6% second instar) across the prairies (up from 7% last week). Development was predicted to be most advanced across southern regions in all three provinces, particularly southeastern Alberta and a region extending south from Regina to the USA border.
Though it is still early in the growing season, grasshopper hatch can vary across the prairies. Model output indicates that development near Vauxhall is one week ahead of Saskatoon and three weeks faster than Grande Prairie. This suggests that peak hatch at Grande Prairie may not occur until late June.
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.
Bertha armyworm (Lepidoptera: Mamestra configurata) – Warm conditions over the past week has advanced pupal development across the southern prairies. Compared to last week, adult emergence is predicted to be 1-7 days earlier. The first map shows that pupal development is well underway across southern and central regions. Average development was 70% (50% last week). Pupal development at a number of locations was 75%.
The second map indicates that development, compared to long-term-average, is slightly greater than average development. Model output indicted that first adult emergence may occur this week in the Vauxhall, Brooks and Regina areas.
IMPORTANT – The table indicates predicted dates of first appearance of adults for specific locations across the prairies. Adult emergence generally occurs within 5-7 days after 80% development.
Reminder – The video below posted by Alberta Agriculture and Forestry’s Scott Meers describes how pheromone traps are used to monitor this important pest of canola.
Those monitoring BAW pheromone traps may want to compare trap “catches” to the following reference photo kindly shared by Saskatchewan Agriculture below:
Flea Beetles (Chrysomelidae: Phyllotreta species) – Be on the lookout for flea beetle damage resulting from feeding on canola cotyledons but also on the stem. Two species, Phyllotreta striolata and P. cruciferae, will feed on all cruciferous plants but they can cause economic levels of damage in canola during the seedling stages.
Remember, the Action Threshold for flea beetles on canola is 25% of cotyledon leaf area consumed. Watch for shot-hole feeding in seedling canola but also watch the growing point and stems of seedlings which are particularly vulnerable to flea beetle feeding. Estimating flea beetle feeding damage can be challenging. Using a visual guide to estimate damage can be helpful. Canola Watch circulated this article but also use the two images (copied below for reference) produced by Dr. J. Soroka (AAFC-Saskatoon) – take it scouting!
Figure 1. Canola cotyledons with various percentages of leaf area consume owing to flea beetle feeding damage (Photo: Soroka & Underwood, AAFC-Saskatoon).
Figure 2. Percent leaf area consumed by flea beetles feeding on canola seedlings (Photo: Soroka & Underwood, AAFC-Saskatoon).
Refer to the flea beetle page from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” as an English-enhanced or French-enhanced version.
Cutworms (Noctuidae) – NEW – Just in time for spring scouting! A new field guide is now available to help growers scout and manage Cutworms! Cutworm Pest of Crops is now available for free in either English or French and is featured at our newCutworm Field Guide!
Keep an eye on fields that are “slow” to emerge, are missing rows, include wilting or yellowing plants, have bare patches, or appear highly attractive to birds – these are areas warranting a closer look. Plan to follow-up by walking these areas later in the day when some cutworm species move above-ground to feed. Start to dig below the soil surface (1-5 cm deep) near the base of a symptomatic plant or the adjacent healthy plant. If the plant is well-established, check within the crown in addition to the adjacent soil. The culprits could be wireworms or cutworms.
Several species of cutworms can be present in fields. They range in colour from shiny opaque, to tan, to brownish-red with chevron patterning. Cutworm biology, species information, plus monitoring recommendations are available in the Prairie Pest Monitoring Network’s Cutworm Monitoring Protocol. Also refer to the Manitoba Agriculture cutworm fact sheet which includes action and economic thresholds for cutworms in several crops.
For Albertans….. If you find cutworms, please consider using the Alberta Pest Surveillance Network’s “2017 Cutworm Reporting Tool”. The map now has reports of pale western and redbacked cutworms in central and southern Alberta so view the live 2017 cutworm map.
Cereal leaf beetle (Oulema melanopus) – As of May 29, 2017, the CLB model indicates that larvae should be present across the southern prairies (Fig. 1). Compared to Lethbridge AB, populations near Brandon MB are predicted to be delayed by approximately five days. At Lethbridge, the hatch should be almost complete, while hatch should be approximately 50% complete near Brandon.
Figure 1. Predicted percent of Cereal leaf beetle (Oulema melanopus) in larval stage
across the Canadian prairies as of May 29, 2017.
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 (~4.4-5.5 mm long).
Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the mid vein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching. Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 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.
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) – Reminder – Biological information and photos of all life stages of this insect can reviewed on the Week 4 post. The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer”.
Degree-day maps of base 9°C are now being produced by Soroka, Olfert, and Giffen (2016) using the Harcourt/North Dakota models. Models predicting the development of Alfalfa weevil across the prairies are updated weekly to help growers time their in-field scouting for second-instar larvae. Compare the following predicted development stages and degree-day values from Soroka (2015) to the map below.
As of May 29, 2017, embryological development (hatch) is predicted to be greatest across south and central regions of the prairies (Fig. 2).
Figure 1. Heat units accumulated necessary for the development of Alfalfa weevil (Hypera postica)
across the Canadian prairies (April 1-May 29, 2017).
The map below reflects the predicted stage of development of alfalfa weevil (as of May 29th) and suggests the percent of the population at first instar stage across the Canadian prairies (as of May 29th).
Figure 2. Predicted percent of H. postica population at first instar stage
across the Canadian prairies (as of May 29, 2017).
Use the photo below as a visual reference to identify alfalfa weevil larvae. Note the white dorsal line, the tapered shape of the abdomen and the dark head capsule.
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.
Pea Leaf Weevil (Sitona lineatus) – This week is our PLW Blitz featuring this pest with: -The Insect of the Week, -Updated model outputs and phenological predictions for 2017 (as of May 29, 2017), and – A NEWLY UPDATED Monitoring Protocol (Vankosky et al. 2017)!
The PLW model was run for Lethbridge AB and Saskatoon SK.Current weather data was used then extended by Long Term Normal climate data (May 30-Jun 30) in order to predict pea leaf weevil phenology. Compared to last week, model output indicated that oviposition has been delayed by ~5-7 days. As of May 29th, phenologies for eggs and larvae were predicted to be similar for both locations (Fig. 1-2).
Figure 1. Pea leaf weevil model predicting phenology for 2017 near Saskatoon SK.
Figure 2. Pea leaf weevil model predicting phenology for 2017 near Lethbridge AB.
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.
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 29, 2017, predicted mean embryological development was 77% (70% last week); the greatest development was predicted to be across southern regions in all three provinces, particularly southern Alberta (Fig. 1). Hatch was predicted for a few, isolated locationswith approximately 7% hatch(Fig. 1).
Figure 1. Predicted embryological development of Migratory grasshopper (Melanoplus
sanguinipes) eggs across the Canadian prairies as of May 29, 2017.
For comparison, the map below (Fig. 2) indicates that the predicted M. sanguinipes hatch is actually slower than normal. This week, 93% of the population should be in the egg stage and 6.5% in the first instar. Predicted warm conditions for May 31 and June 1 should result in completion of the egg stage. Though it is still early in the growing season, grasshopper hatch can vary across the prairies.
Figure 2. Predicted embryological development of Migratory grasshopper (Melanoplus sanguinipes) eggs
across the Canadian prairies as of May 29, 2017, using Long Term Normal data.
Bertha armyworm (Lepidoptera: Mamestra configurata) – As of May 28th, predicted pupal development is well underway. We are fortunate to have two methods projecting pupal development: –> Figure 1 reflects pupal development BASED ON DEGREE DAYS ONLY. –> Figure 2 reflects pupal development BASED ON CLIMEX MODELLING (i.e., incorporates environmental data + biological data for organisms) AND legend is designed to estimate WHEN PHEROMONE TRAPS SHOULD BE DEPLOYED (i.e., pheromone traps are best deployed at ~80% pupal development).
Figure 1. Predicted stage of pupal development of overwintered Bertha armyworm (based on Degree-Day heat units) set to emerge in 2017.
FIGURE 2. Predicted pupal development of Bertha armyworm (based on Climex model and legend designed to reflect that pheromone traps are best deployed at ~80% pupal development).
More specifically, Figure 2 shows the average pupal development is 50% (36% last week), and as high as 75% at a number of locations. The three graphs below show that adult emergence is predicted to be six days sooner in the Winnipeg region than in fields near Vegreville and ten days sooner than the Yorkton area.
IMPORTANT – The table indicates predicted dates of first appearance of adults for specific locations across the prairies. We generally suggest that traps go out when pupal development is at 80%. Adult emergence generally occurs within 5-7 days after 80% development. As of May 29, 2017, there is a large area in southern Alberta that is greater than 70%.
Reminder – These maps will be updated weekly to aid those who deploy and monitor this moth using pheromone traps. The video below posted by Alberta Agriculture and Forestry’s Scott Meers describes how pheromone traps are used to monitor this important pest of canola.
Flea Beetles (Chrysomelidae: Phyllotreta species) – Be on the lookout for flea beetle damage resulting from feeding on canola cotyledons but also on the stem. Two species, Phyllotreta striolata and P. cruciferae, will feed on all cruciferous plants but they can cause economic levels of damage in canola during the seedling stages.
Remember, the Action Threshold for flea beetles on canola is 25% of cotyledon leaf area consumed. Watch for shot-hole feeding in seedling canola but also watch the growing point and stems of seedlings which are particularly vulnerable to flea beetle feeding. Estimating flea beetle feeding damage can be challenging. Using a visual guide to estimate damage can be helpful. Canola Watch circulated this article but also use the two images (copied below for reference) produced by Dr. J. Soroka (AAFC-Saskatoon) – take it scouting!
Figure 1. Canola cotyledons with various percentages of leaf area consume owing to flea beetle feeding damage (Photo: Soroka & Underwood, AAFC-Saskatoon).
Figure 2. Percent leaf area consumed by flea beetles feeding on canola seedlings (Photo: Soroka & Underwood, AAFC-Saskatoon).
Refer to the flea beetle page from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” as an English-enhanced or French-enhanced version.
Cutworms (Noctuidae) – NEW – Just in time for spring scouting! A new field guide is now available to help growers scout and manage Cutworms! Cutworm Pest of Crops is now available for free in either English or French and is featured at our newCutworm Field Guide! Also be sure to check the Insect of the Week throughout May – it highlights cutworms! Be sure to read more about Dingy cutworms.
Dingy cutworm larva (cc John Gavloski, Manitoba Agriculture)
Several species of cutworms can be present in fields. They range in colour from shiny opaque, to tan, to brownish-red with chevron patterning. Cutworm biology, species information, plus monitoring recommendations are available in the Prairie Pest Monitoring Network’s Cutworm Monitoring Protocol. Also refer to the Manitoba Agriculture cutworm fact sheet which includes action and economic thresholds for cutworms in several crops. Keep an eye on fields that are “slow” to emerge, are missing rows, include wilting or yellowing plants, have bare patches, or appear highly attractive to birds – these are areas warranting a closer look. Plan to follow-up by walking these areas later in the day when some cutworm species move above-ground to feed. Start to dig below the soil surface (1-5 cm deep) near the base of a symptomatic plant or the adjacent healthy plant. If the plant is well-established, check within the crown in addition to the adjacent soil. The culprits could be wireworms or cutworms. For Albertans….. If you find cutworms, please consider using the Alberta Pest Surveillance Network’s “2017 Cutworm Reporting Tool”. The map now has reports of pale western and redbacked cutworms in central and southern Alberta so view the live 2017 cutworm map.
Cereal leaf beetle (Oulema melanopus) – As of May 22, 2017, the CLB model indicates that oviposition is well underway across the southern prairies. Compared to southern Alberta and Saskatchewan, populations in southern Manitoba are predicted to be delayed by approximately five days (Fig. 1). Compared to 2016, development in 2017 is approximately 1 week later. Hatch is predicted to occur in isolated areas.
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 (~4.4-5.5 mm long).
Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the mid vein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching. Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 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.
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”.
Pea Leaf Weevil (Sitona lineatus) – The pea leaf weevil simulation model will be used to monitor weevil development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of weevil development stages based on biological parameters for Sitona lineatus.
The PLW model was run for Lethbridge AB and Saskatoon SK. Meteorological data (April 1 – May 15, 2017) and climate data (May 16- June 30) were used to predict PLW phenology. Output indicates that PLW oviposition in Lethbridge is approximately one week earlier than Saskatoon.Reminder – Access last week’s PLW model output predictions here.
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. 1, 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.
Alfalfa Weevil (Hypera postica) – 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).
Degree-day maps of base 9°C are now being produced by Soroka, Olfert, and Giffen (2016) using the Harcourt/North Dakota models. Models predicting the development of Alfalfa weevil (Hypera postica) across the prairies are updated weekly to help growers time their in-field scouting for second-instar larvae. Compare the following predicted development stages and degree-day values from Soroka (2015) to the map below.
This week, embryological development is greatest across south and central regions of Alberta and Saskatchewan and across southern Manitoba. Early hatch is predicted to occur in a region near Brooks AB and Regina SK and south to the USA border.
Use the figure below as a visual reference to identify alfalfa weevil larvae. Note the white dorsal line, the tapered shape of the abdomen and the dark head capsule.
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.
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 22, 2017, predicted mean embryological development was 70% (66% last week); the greatest development was predicted to be across southern regions in all three provinces (similar to long term averages; Fig. 1).
Figure 1. Simulation model outputs mapped to predict the embryological development of Migratory grasshopper (Melanoplus sanguinipes) eggs across the Canadian prairies as of May 15, 2017).
Model output indicates that development near Regina SK (Fig 2, Top) is slightly greater than Lethbridge AB (Fig. 2, Middle). Hatch in Lethbridge is predicted to be two weeks ahead of model predictions for Grande Prairie AB (Fig 2, Bottom).
Figure 2. Predicted development of Migratory grasshoppers near Regina SK (Top), Lethbridge AB (Middle), and Grande Prairie AB (Bottom).
Bertha armyworm (Lepidoptera: Mamestra configurata) – This week, predicted pupal development is well underway. Average development is 36% (27% last week); average development is 37% (Fig. 1).
Figure 1. Predicted stage of pupal development of overwintered Bertha armyworm set to emerge in 2017.
Reminder – These maps will be updated weekly to aid those who deploy and monitor this moth using pheromone traps. The video below posted by Alberta Agriculture and Forestry’s Scott Meers describes how pheromone traps are used to monitor this important pest of canola.
Flea Beetles (Chrysomelidae: Phyllotreta species) – Be on the lookout for flea beetle damage resulting from feeding on canola cotyledons but also on the stem. Two species, Phyllotreta striolata and P. cruciferae, will feed on all cruciferous plants but they can cause economic levels of damage in canola during the seedling stages.
Remember, the Action Threshold for flea beetles on canola is 25% of cotyledon leaf area consumed. Watch for shot-hole feeding in seedling canola but also watch the growing point and stems of seedlings which are particularly vulnerable to flea beetle feeding.
Estimating flea beetle feeding damage can be challenging. Using a visual guide to estimate damage can be helpful. Canola Watch circulated this article but also use the two images (copied below for reference) produced by Dr. J. Soroka (AAFC-Saskatoon) – take it scouting!
Figure 1. Canola
cotyledons with various percentages of leaf area consume owing to flea beetle
feeding damage (Photo: Soroka & Underwood, AAFC-Saskatoon).
Figure 2.
Percent leaf area consumed by flea beetles feeding on canola seedlings
(Photo: Soroka & Underwood, AAFC-Saskatoon).
Refer to the flea beetle page from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” as an English-enhanced or French-enhanced version.
Cutworms (Noctuidae) – NEW – Just in time for spring scouting! A new field guide is now available to help growers scout and manage Cutworms! Cutworm Pest of Crops is now available for free in either English or French and is featured at our newCutworm Field Guide! Also be sure to check the Insect of the Week throughout May – it highlights cutworms! Be sure to read more about Army cutworms.
Army cutworm larva (cc-by 3.0 Whitney Cranshaw, bugwood.org)
Several species of cutworms can be present in fields. They range in colour from shiny opaque, to tan, to brownish-red with chevron patterning. Cutworm biology, species information, plus monitoring recommendations are available in the Prairie Pest Monitoring Network’s Cutworm Monitoring Protocol. Also refer to the Manitoba Agriculture cutworm fact sheet which includes action and economic thresholds for cutworms in several crops. Keep an eye on fields that are “slow” to emerge, are missing rows, include wilting or yellowing plants, have bare patches, or appear highly attractive to birds – these are areas warranting a closer look. Plan to follow-up by walking these areas later in the day when some cutworm species move above-ground to feed. Start to dig below the soil surface (1-5 cm deep) near the base of a symptomatic plant or the adjacent healthy plant. If the plant is well-established, check within the crown in addition to the adjacent soil. The culprits could be wireworms or cutworms. For Albertans….. If you find cutworms, please consider using the Alberta Pest Surveillance Network’s “2017 Cutworm Reporting Tool”. Once data entry occurs, growers can view the live 2017 cutworm map which is updated daily.
Cereal leaf beetle (Oulema melanopus) – As of May 15, 2017, the CLB model predicts that oviposition should be underway in the Lethbridge, Swift Current and Brandon areas. Compared to southern Alberta and Saskatchewan, populations in southern Manitoba are predicted to be delayed by approximately a week.
Lifecycle and Damage: Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 1). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than the males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelter belts, deciduous and conifer forests. They emerge in the spring once temperature reaches 10-15 ºC and are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals.
Figure 1. Adult Oulema melanopus (~4.4-5.5 mm long).
Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the mid vein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching. Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 2). When the larva completes its growth, it drops to the ground and pupates in the soil.
Figure 2. Larval stage of Oulema melanopus with characteristic feeding damage visible on leaf.
Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 – 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.
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) – 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).
Degree-day maps of base 9°C are now being produced by Soroka, Olfert, and Giffen (2016) using the Harcourt/North Dakota models. Models predicting the development of Alfalfa weevil (Hypera postica) across the prairies are updated weekly to help growers time their in-field scouting for second-instar larvae. Compare the following predicted development stages and degree-day values from Soroka (2015) to the map below.
This week, the predictive model output for Brooks AB suggests that oviposition is well underway (i.e., in areas of the map below highlighted chocolate-brown). The initial first instar larvae may occur by next week.
Use the figure below as a visual reference to identify alfalfa weevil larvae. Note the white dorsal line, the tapered shape of the abdomen and the dark head capsule.
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.
Pea Leaf Weevil (Sitona lineatus) – The pea leaf weevil simulation model will be used to monitor weevil development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of weevil development stages based on biological parameters for Sitona lineatus.
Model output predicted that flight of pea leaf weevil adults was significantly earlier in Lethbridge than Saskatoon in 2017. In the figure below, note the red line predicting adults emerging from overwintering then the yellow line predicting overwintered adults taking flight this spring for Lethbridge AB (Fig. 1, Upper) and Saskatoon SK (Fig. 1, Lower).
Figure 1. Model output predicting development of pea leaf weevil in Lethbridge AB (Upper) and Saskaton SK (Lower) in the spring of 2017.
Reminder – In 2016, the distribution of pea leaf weevil increased dramatically based on both damage assessments AND collection of adults in 2016 (Fig. 2).
Figure 2. Distribution of pea leaf weevil (Sitona lineatus) based on surveying conducted in 2016 (Olfert et al. 2017).
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.
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 15, 2017, the predicted mean embryological development was only slightly ahead of last week at 66% (compared to 62% last week), and similar to long term averages (64%; Fig. 1). Although it is still early in the growing season, grasshopper hatch can vary across the prairies. For example, model output indicated that the hatch in Vauxhall AB was predicted to be about a week ahead of Saskatoon SK. As a result, timing of peak hatch could be 10-14 days earlier in Vauxhall than Saskatoon.
Figure 1. Simulation model outputs mapped to predict the embryological development of Migratory grasshopper (Melanoplus sanguinipes) eggs across the Canadian prairies as of May 15, 2017).
Reminder – The Prairie Pest Monitoring Network’s 2017 Grasshopper Forecast Map (Fig. 2) was released in January. While spring temperatures, soil moisture conditions, and precipitation can all have an impact on overwintered grasshopper eggs, growers in areas highlighted orange or red in the map below should be vigilant as nymphs begin to hatch this season.
Figure 2. Prairie Pest Monitoring Network’s 2017 Grasshopper Forecast Map.
Bertha armyworm (Lepidoptera: Mamestra configurata) – The first map (Fig. 1) shows that predicted pupal development is well underway (average 27%).
Figure 1. Predicted stage of pupal development of overwintered Bertha armyworm set to emerge in 2017.
The second map (Fig. 2) indicates that predicted development this year is ahead of long term averages in Manitoba and Saskatchewan.
Figure 2. Pupal development of overwintered Bertha armyworm in 2017 compared to long-term averages observed across the Canadian prairies.
These maps will be updated weekly to aid those who deploy and monitor this moth using pheromone traps. The video below posted by Alberta Agriculture and Forestry’s Scott Meers describes how pheromone traps are used to monitor this important pest of canola.
Field scouting is critical – it enables the identification of potential risks to crops. However, the identification of these insect pests PLUS the application of established monitoring methods will enable growers to make informed pest management decisions.
Whenever possible, monitor and compare pest densities to established economic or action thresholds to protect and preserve pollinators and beneficial arthropods. Economic thresholds, by definition, help growers avoid crop losses related to outbreaking insect pest species.
Flea Beetles (Chrysomelidae: Phyllotreta species) – Be on the lookout for flea beetle damage resulting from feeding on canola cotyledons but also on the stem.
Remember, the Action Threshold for flea beetles on canola is 25% of cotyledon leaf area consumed. Shot-hole feeding is the traditional damage in seedling canola but watch the growing point and stems of seedlings. Refer to the flea beetle page from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” as an English-enhanced or French-enhanced version.
Cutworms (Noctuidae) – NEW – Just in time for spring scouting! A new field guide is now available to help growers scout and manage Cutworms! Cutworm Pest of Crops is now available for free in either English or French and is featured at our newCutworm Field Guide! Also be sure to check the Insect of the Week throughout May – it highlights cutworms! Be sure to read more about Redbacked cutworms.
Figure 1. Redbacked cutworms retrieved from a Manitoban field (Photo: J. Gavloski)
Several species of cutworms can be present in fields. They range in colour from shiny opaque, to tan, to brownish-red with chevron patterning. Cutworm biology, species information, plus monitoring recommendations are available in the Prairie Pest Monitoring Network’s Cutworm Monitoring Protocol. Also refer to the Manitoba Agriculture cutworm fact sheet which includes action and economic thresholds for cutworms in several crops. Keep an eye on fields that are “slow” to emerge, are missing rows, include wilting or yellowing plants, have bare patches, or appear highly attractive to birds – these are areas warranting a closer look. Plan to follow-up by walking these areas later in the day when some cutworm species move above-ground to feed. Start to dig below the soil surface (1-5 cm deep) near the base of a symptomatic plant or the adjacent healthy plant. If the plant is well-established, check within the crown in addition to the adjacent soil. The culprits could be wireworms or cutworms. For Albertans….. If you find cutworms, please consider using the Alberta Pest Surveillance Network’s “2017 Cutworm Reporting Tool”. Once data entry occurs, growers can view the live 2017 cutworm map which is updated daily.
Cereal leaf beetle (Oulema melanopus) – As
of May 8, 2017, CLB model output predicted that oviposition is underway in populations
that may be present in the Lethbridge, Swift Current and Brandon areas. Compared
to 2016, phenological development in 2017 is approximately 1 week later.
Lifecycle and Damage: Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 1). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than the males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelter belts, deciduous and conifer forests. They emerge in the spring once temperature reaches 10-15 ºC and are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals.
Figure 1. Adult Oulema melanopus (~4.4-5.5 mm long).
Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the mid vein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching. Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 2). When the larva completes its growth, it drops to the ground and pupates in the soil.
Figure 2. Larval stage of Oulema melanopus with characteristic feeding damage visible on leaf.
Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 – 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.
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”.
Pea Leaf Weevil (Sitona lineatus) – This species was one of the “big” insects of 2016’s field crop growing season. The distribution of pea leaf weevil increased dramatically based on both damage assessments AND collection of adults in 2016 (Fig. 1) compared to previous years (Fig. 2).
Figure 1. Distribution of pea leaf weevil (Sitona lineatus) based on surveying conducted in 2016 (Olfert et al. 2017).
Figure 2. Distributions of pea leaf weevil based on surveying conducted between 2012-2015 (Olfert et al. 2017).
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.
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 8, 2017, predicted mean embryological development was 62% (56% last week); the greatest development was predicted to be across southern Saskatchewan. Embryological development was very similar to long term averages (60%) though well behind 2016 (74%). Hatch was not predicted for any locations.
Reminder – The Prairie Pest Monitoring Network’s 2017 Grasshopper Forecast Map (Figure 1) was released in January. While spring temperatures, soil moisture conditions, and precipitation can all have an impact on overwintered grasshopper eggs, growers in areas highlighted orange or red in the map below should be vigilant as nymphs begin to hatch this season.
Figure 1. Prairie Pest Monitoring Network’s 2017 Grasshopper Forecast Map.
Field scouting is critical – it enables the identification of potential risks to crops. Field crop production systems across the Canadian prairies will suffer insect pest outbreaks. However, the identification of these insect pests PLUS the application of established monitoring methods will enable growers to make informed pest management decisions.
For 2017, we offer TWO generalized insect pest scouting charts to aid in-field scouting on the Canadian prairies:
Growers can access biological information about the pest and its natural enemies, the type of damage it causes, how to monitor, and what pest management strategies might apply to help protect yield and quality (Fig. 1).
Whenever possible, monitor and compare pest densities to established economic or action thresholds to protect and preserve pollinators and beneficial arthropods. Economic thresholds, by definition, help growers avoid crop losses related to outbreaking insect pest species.
Good luck with your scouting!
Figure 1. Example of Bertha armyworm pages from the above field guide:
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 1, 2017, model output predicted embryological mean development was 56%; the greatest development was predicted to be across the southern prairies. Embryological development was very similar to long term averages (57%) though marginally slower than 2016 (62%).
Reminder – The Prairie Pest Monitoring Network’s 2017 Grasshopper Forecast Map (Figure 1) was released in January. While spring temperatures, soil moisture conditions, and precipitation can all have an impact on overwintered grasshopper eggs, growers in areas highlighted orange or red in the map below should be vigilant as nymphs begin to hatch this season.
Figure 1. Prairie Pest Monitoring Network’s 2017 Grasshopper Forecast Map.
Grasshoppers (Acrididae) – Previous model predictions related to hatch and nymphal instar development can be reviewed here.
The following image showing various stages of Camnulla pellucida 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.
Generally, the economic threshold for grasshoppers in cereals is 8-12 per square metre but will vary by crop and growing conditions.
Figure 1. Life stages of Camnulla pellucidawhich including eggs, first-fifth instar nymphs and adult (L-R).
Swede midge (Contarinia nasturtii) – Reminder –Pheromone traps captured the first swede midge of 2016 between May 25 and 31 in northeastern Saskatchewan. This is substantially earlier (6-7 weeks) compared to 2014 and 2015. The earlier emergence pattern is likely due to the mild winter and warm spring weather combined with adequate moisture levels. Emergence traps indicate a moderate number of swede midge have emerged near Carrot River, Saskatchewan, and producers should monitor their canola fields for damage symptoms.
Figure 1. Swede midge infested canola buds which are enlarged with sepals fused together.
Figure 2. Swede midge large (~1mm long; yellowish-white) feeding within canola flower.
Swede midge scouting tips for in-field monitoring: • Watch for unusual plant structures and plant discolourations then follow-up by closely scrutinizing the plant for larvae. • The growing tip may become distorted and produce several growing tips or none at all, young leaves may become swollen, crinkled or crumpled and brown scarring caused by larval feeding may be seen on the leaf petioles and stems. • Flowers may fail to open. • Young plants that show unusual growth habits should be examined carefully for damage and larvae; especially if the sticky liners have many flies resembling midges (swede midges are about the size of orange blossom wheat midge but are not orange). • Larvae can be seen with a hand lens. • Refer to the Canola Watch article by Dr. Julie Soroka for more information on swede midge and watch for a new Ontario fact sheet produced by Baute et al. 2016. Note the distribution map of confirmed symptoms and populations of swede midge (red dots) on the Canadian prairies (Soroka and Andreassen 2015).
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).
Swede midge (Contarinia nasturtii) – Reminder – Pheromone traps captured the first swede midge of 2016 between May 25 and 31 in northeastern Saskatchewan. This is substantially earlier (6-7 weeks) compared to 2014 and 2015.
The earlier emergence pattern is likely due to the mild winter and warm spring weather combined with adequate moisture levels. Emergence traps indicate a moderate number of swede midge have emerged near Carrot River, Saskatchewan, and producers should monitor their canola fields for damage symptoms.
Figure 1. Swede midge infested canola buds which are enlarged with sepals fused together.
Figure 2. Swede midge large (~1mm long; yellowish-white) feeding within canola flower.
Swede midge scouting tips for in-field monitoring: • Watch for unusual plant structures and plant discolourations then follow-up by closely scrutinizing the plant for larvae. • The growing tip may become distorted and produce several growing tips or none at all, young leaves may become swollen, crinkled or crumpled and brown scarring caused by larval feeding may be seen on the leaf petioles and stems. • Flowers may fail to open. • Young plants that show unusual growth habits should be examined carefully for damage and larvae; especially if the sticky liners have many flies resembling midges (swede midges are about the size of orange blossom wheat midge but are not orange). • Larvae can be seen with a hand lens. • Refer to the Canola Watch article by Dr. Julie Soroka for more information on swede midge and watch for a new Ontario fact sheet produced by Baute et al. 2016.
Note the distribution map of confirmed symptoms and populations of swede midge (red dots) on the Canadian prairies (Soroka and Andreassen 2015).
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.
CSPW emerge from overwintering in the spring as soil temperatures warm to ~15°C. CSPW utilize several flowering hosts including wild mustard, flixweed, hoary cress, stinkweed and volunteer canola. CSPW move to canola during the bud to early flower stages and will feed on pollen and buds, causing flowers to die.
The map below reflects CSPW densities observed in 2015. Growers situated within or adjacent to areas of the map highlighted yellow, orange and red will need to be scouting with a sweep-net as their canola fields initiate flowering.
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.
Alfalfa Weevil (Hypera postica)– Earlier predictive model outputs can be reviewed by searching the Blog for “Alfalfa weevil” or use the Label Index located to the right of the screen to sort and review all “Alfalfa weevil” posts for 2016.
Reminder – 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).
Economic thresholds for Alfalfa weevil (adapted from Soroka 2015) vary by crop type (hay or seed), area fed upon and larval densities. In hay fields, forage losses can be economic if one or more of the following symptoms are noted: ● if 25-50 % of the leaves on the upper one-third of the stem show damage, or ● if 50-70% of the terminals are injured, or ● if 1 to 3 third or fourth instar larvae occur per stem (with shorter stems having lower economic thresholds and 3 or more larvae requiring treatment no matter what the alfalfa height), or ● 20-30 larvae per sweep occur when 12% leaf loss is acceptable. ● Also consider these two points: 1. Early cutting of the first growth of alfalfa or insecticide treatment will reduce alfalfa weevil populations. 2. If the hay crop value is high and weevil injury is seen or 2 or more larvae per stem reappear in regrowth after cutting, insecticide may be necessary (if a second cut is anticipated).
In alfalfa seed fields: ● Economic thresholds are 20-25 third to fourth instar larvae per sweep or 35-50% of the foliage tips showing damage. ● Thresholds increase with the height of the alfalfa, and decrease in drought conditions. ● Also know that several small wasps parasitize alfalfa weevil larvae and adults, and in the past these natural control agents kept the weevil in check in most years. One of these wasps, Bathyplectes curculionis (Thomson), parasitizes alfalfa weevil in Alberta and Saskatchewan, and is now found in Manitoba.
