This week’s “Insect of the Week” is the Pea Leaf Weevil. Larval hosts are field peas and faba beans. Adults can spread to other cultivated and wild legumes, such as alfalfa, beans and lentils. Each adult female lays up to 300 eggs in one summer! The eggs hatch in the soil near developing plants and larvae move to feed on nitrogen-fixing nodules. This results in partial or complete inhibition of nitrogen fixation by the plant, causing poor plant growth. Adults feed on leaves and growing points of seedlings, causing notches in leaf margins.
Ross Weiss, Serge Trudel, Owen Olfert and prairiepest_admin
THE WEEK OF MAY 29, 2017: Wind trajectory data processing by AAFC-Saskatoon Staff began in April. Reverse Trajectories track arriving air masses back to their point of origin while Forward Trajectories predict favourable winds expected to arrive across the Canadian Prairies for the week of May 23, 2017: Reverse trajectories (RT) Overall, the number of RTs entering the prairies from the Pacific
Northwest has been lower than average. The map (Fig. 1) shows that the greatest number
of RTs from the Pacific Northwest continued to be across southern Alberta.
Figure 1. Number of Reverse Trajectories (RT) originating in the Pacific Northwest that
arrived at sites across the Canadian prairies from April 1-May 29, 2017.
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).
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.
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.
Ross Weiss, David Giffen, Owen Olfert and prairiepest_admin
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.
Wheat Midge (Sitodiplosis mosellana) – Predictive modelling will be used again to help forecast wheat midge emergence across the Canadian prairies. The maps below predicts the geographic distribution and corresponding accumulation of heat units necessary for wheat midge to emerge from puparia developing in the soil.
Since last week, the wheat midge model indicates that wheat midge larvae should be moving to the soil surface this week and the adult emergence has been delayed by 5-7 days (i.e., now predicted to start the first week of June).
More information about Wheat midge can be found by accessing the pages from the new “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide”. View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.
Ross Weiss, David Giffen, Owen Olfert and prairiepest_admin
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.
Provincial entomologists provide insect pest updates throughout the growing season so we have attempted to link to their most recent information:
Manitoba’s Insect and Disease Update for 2017 is prepared by John Gavloski and Pratisara Bajracharya and have now been posted (May 24, 2017, May 31, 2017). Read the latest issue which: – Reports low insect pest issues so far in that province. – Notes a limited amount of spraying for cutworms. – Includes detailed flea beetle monitoring tips. – Reports low numbers through May in Diamondback pheromone traps. – And finally, Manitoba Agriculture is advising Manitoban cooperators to deploy Bertha armyworm pheromone traps June 5-10, 2017. Saskatchewan’s 2017 Crop Production News – Issue #1 (date) is now posted and includes insect pest information prepared by Scott Hartley and Danielle Stephens. Read the latest update including: – Information on wireworms, cutworms and other arthropods that will be present in the soil during scouting. Watch for Alberta Agriculture and Forestry’s Call of the Land and access the most recent Insect Update (June 1, 2017) provided by Scott Meers who: – Emphasized the importance of scouting for flea beetle feeding in canola and application of action threshold of 25% when examining the cotyledons. – Noted lower reports of cutworms last week. – And finally, Albertan cooperators are advised to target June 12, 2017 to deploy Bertha armyworm pheromone traps across that province.
Crop reports are produced by: • Manitoba Agriculture, Rural Development (May 29, 2017) • Saskatchewan Agriculture Crop Report (May 23-29, 2017) • Alberta Agriculture and Forestry Crop Report (May 23, 2017) International reports are produced by: • The United States Department of Agriculture’s Crop Progress Report (May 30, 2017)
If your fields are near one of Environment Canada’s PRAIRIE Radar Stations, consider accessing weather radar maps in video format show either the past 1 OR 3 hours of spatio-temporal maps of precipitation events. These maps can help growers review where and how much precipitation fell nearby. Screen shots of Environment Canada’s webpages are below for reference and red text and arrows have been added to help you navigate the webpage.
Health Canada’s Pest Management Regulatory Agency launched a new mobile app to access pesticide labels registered for use in Canada. The App helps homeowners, farmers, industry, provincial and federal organizations access details for pest control products from a smartphone or tablet (Fig. 1).
Users can save searches, download product labels to their ‘Favourites’ which can even be accessed while offline. ‘Favourites’ will also auto-update when accessed online. Pesticide labels can be searched based by product name or active ingredient (e.g., to review detailed explanations on proper product use and necessary precautions).
We again track the migration of the Monarch butterflies as they move north by checking the 2017 Monarch Migration Map! A screen shot of the map has been placed below as an example (retrieved 01Jun2017) but follow the hyperlink to check the interactive map! They’ve migrated into southern Ontario and Quebec!
Cicadas are well known for their long life cycles. Some species follow an annual life cycle but the more “famous” have broods that emerge on 13- or 17-year cycles. The big news this year in North America is that Brood X cicadas are emerging 4 years earlier than anticipated!
Researchers originally following the emergence of Brood VI cicadas in South Carolina and Georgia observed Brood X cicadas emerging this spring. The phenomenon was then observed in North Carolina, Virginia, Maryland, the District of Columbia, Ohio and Indiana.
Researchers continue to follow the emergence of both broods of cicadas but the earlier-than-expected appearance of Brood X is described to be related to, “warming climate, with more warm weeks a year during which the underground nymphs can grow” which, “could be triggering some cicadas to emerge ahead of their brood”. Read the Scientific American article to learn more.