Weekly Update (June 11, 2020; Wk 07) Otani, Weiss, Rounce, Trudel, Svendsen, Gavloski, Turkington, Olfert, Vankosky

This time it's a BIG Weekly Update - several predictive model updates have been generated this week! Find updated information for bertha armyworm, grasshoppers, cereal leaf beetle, alfalfa weevil, wheat midge and pea leaf weevil.  A new Pests & Predators podcast is available and much more.  Keep scrolling down and it's time to get in fields to scout!

Access information to support your in-field insect monitoring efforts in the complete Weekly Update either as a series of Posts for Week 7 OR a downloadable PDF.

Stay Safe!

Questions or problems accessing the contents of this Weekly Update?  Please e-mail either Meghan.Vankosky@canada.ca or Jennifer.Otani@canada.ca.  Past “Weekly Updates” can be accessed on our Weekly Update page.

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Weather synopsis

Weather synopsis –  This week, June 1-7, 2020, temperature and moisture conditions varied significantly across the prairies (Table 1; Fig. 1). Compared to Alberta, average 7-day temperatures were much warmer in Manitoba (Fig. 1). Average 30-day (May 2-31, 2020)  temperatures were warmest across central and southern regions of all three provinces (Table 2; Fig. 2). Temperature anomalies indicated that most of the prairies have experienced temperatures that have been up to 2 °C cooler than normal (May 1-31, 2020). 

Table 1.  7 day temperature and rainfall summary (June 1-7, 2020)

Table 2.  30 day temperature and rainfall summary (May 9 - June 7, 2020).

Figure 1. Observed average temperatures across the Canadian prairies for the past seven days (June 1-7, 2020).

Figure 2. Observed average temperatures across the Canadian prairies for the past 30 days (May 9-June 7, 2020).

This past week, rainfall amounts were well above average across central Alberta; most of the prairies had minimal rain (Table 1; Fig. 3).  Eastern Saskatchewan and Manitoba have had the lowest 30 day cumulative rainfall amounts; precipitation has been greatest in Alberta so far this growing season (Table 2; Fig. 4). The recent rain has resulted in above normal rainfall (compared to long term normal) for most of Alberta (Fig. 5). Conditions continue to be dryer than normal across most of Saskatchewan and Manitoba (Fig. 5). Similar to last week, prairie rainfall amounts for the past 30 days have been approximately 125 % of normal.

Figure 4. Observed cumulative precipitation across the Canadian prairies for the past seven days (June 1-7, 2020).

Figure 5. Observed cumulative precipitation across the Canadian prairies for the past 30 days (May 9-June 7, 2020).

Figure 6. Percent of average precipitation the past 30 days (as of June 7, 2020).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (07Jun2020).  

Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The growing degree day map (GDD) (Base 5 ºC, April 1-June 8, 2020) is below (Fig. 7):

Figure 7. Growing degree day map (Base 5 °C) observed across the Canadian prairies for 
the growing season (April 1-June 8, 2020).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (11Jun2020).  
Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The growing degree day map (GDD) (Base 10 ºC, April 1-June 8, 2020) is below (Fig. 8):

Figure 8. Growing degree day map (Base 10°C) observed across the Canadian prairies for 
the growing season (April 1-June 8, 2020).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (11Jun2020).  
Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The lowest temperatures (°C) observed the past seven days ranged from <-5 to >6 °C in the map below (Fig. 9).

Figure 9. Lowest temperatures (°C) observed across the Canadian prairies the past seven days (June 4-10, 2020).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (11Jun2020).  

Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The highest temperatures (°C) observed the past seven days ranged from <6 to >28 °C in the map below (Fig. 10).

Figure 10. Highest temperatures (°C) observed across the Canadian prairies the past seven days (June 4-10, 2020).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (11Jun2020).  

Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true&reset=1588297059209

The maps above are all produced by Agriculture and Agri-Food Canada.  Growers can bookmark the AAFC Current Conditions Drought Watch Maps for the growing season.  More weather data can be access at the AAFC Drought Watch website, Environment Canada's Historical Data website, or your provincial weather network.

Wind Trajectories

Agriculture and Agri-Food Canada (AAFC) and Environment and Climate Change Canada (ECCC) have been working together to study the potential of trajectories for monitoring insect movements since the late 1990s.

The entire list of 2020 Wind Trajectory Reports is available here.
→ Read the WEEKLY Wind Trajectory Report for Wk07 (released June 8, 2020).

Bertha armyworm monitoring

Bertha armyworm (Lepidoptera: Mamestra configurata) - Model simulations to June 7, 2020 indicate that BAW pupal development varies widely across the prairies (Fig. 1). Development is predicted to be greatest across the southern prairies. Depending on temperature, BAW adults can be expected to emerge in 5-10 days. 

As a reminder to cooperators monitoring BAW with pheromone traps, the traps should be placed in the field once pupal development in your region reaches 80% (Fig. 1).

Figure 1. Predicted bertha armyworm (Mamestra configurata) pupal development across
the Canadian prairies as of June 7, 2020. 

Recap - We again include last week's Table 1 with the earlier predicted BAW emergence dates.

Table 1. The estimated date on which bertha armyworm pupae will have completed 80% of pupal development and when adult moths are expected to begin emerging at six locations across western Canada.

Over the next weeks, watch your provincial monitoring networks who will weekly compile cumulative pheromone-baited traps in Alberta, Saskatchewan, and Manitoba.

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also refer to the bertha armyworm pages within the "Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide" which is a free downloadable document as both an English-enhanced or French-enhanced version.

Refer to the PPMN Bertha armyworm monitoring protocol for help when performing in-field scouting.  Use the images below (Fig. 3) to help identify egg masses and the economically important larvae in canola.  Review the 2019 Insect of the Week which featured bertha armyworm and its doppelganger, the clover cutworm!

Figure 3. Stages of bertha armyworm from egg (A), larva (B), pupa (C) to adult (D).
Photos: J. Williams (Agriculture and Agri-Food Canada)

Diamondback moth

Diamondback moth (Plutellidae: Plutella xylostella) - Once diamondback moth is present in the area, it is important to monitor individual canola fields for larvae.  Warm growing conditions can quickly translate into multiple generations in a very short period!

Wind Trajectory Updates - Wind trajectory models used to deliver an early-warning system for the origin and destination of migratory invasive species indicated arrival events of air currents potentially carrying migrating diamondback moths from more southerly regions.  Access the Weekly Wind Trajectory Report (released June 8, 2020) to review where wind trajectories originating over Mexico, California, Texas or the Pacific Northwest cross locations in Manitoba, Saskatchewan, and Alberta.

Weekly Pheromone-baited Trapping Results - Early season detection of diamondback moth is improved through the use of pheromone-baited delta traps deployed in fields across the Canadian prairies.  As they become available, moth reporting numbers observed in Alberta, Saskatchewan and Manitoba are linked here. Check these sites to assess cumulative counts and relative risk in your geographic region.

Monitoring:
Remove the plants in an area measuring 0.1 m² (about 12" square), beat them on to a clean surface and count the number of larvae (Fig. 1) dislodged from the plant. Repeat this procedure at least in five locations in the field to get an accurate count.

Figure 1. Diamondback larva measuring ~8 mm long.
Note brown head capsule and forked appearance of prolegs on posterior.

Figure 2. Diamondback moth pupa within silken cocoon.

Economic threshold for diamondback moth in canola at the advanced pod stage is 20 to 30 larvae/ 0.1 m² (approximately 2-3 larvae per plant).  Economic thresholds for canola or mustard in the early flowering stage are not available. However, insecticide applications are likely required at larval densities of 10 to 15 larvae/ 0.1 m² (approximately 1-2 larvae per plant).

Figure 3. Diamondback moth.

Biological and monitoring information for DBM is posted by Manitoba Agriculture, Saskatchewan Agriculture, and the Prairie Pest Monitoring Network.  

More information about Diamondback moths can be found by accessing the pages from the  "Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide".  View ONLY the Diamondback moth page but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.

Predicted grasshopper development

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 7, 2020, predicted embryonic development was 82% (78% last week) and is 6% greater than long term average values. The simulation estimates that hatch is well underway and development of nymphs was greater than average for all 8 locations that are listed in Table 1. The prairie average for nymph development is currently estimated at 20% and is well above the long term average of 4.5% (Fig. 1). Average nymph development last week was estimated to be 7%. 
 
Table 1.  Predictive model output estimates for Melanoplus sanguinipes development (% of total population for each location) at selected sites across the Canadian prairie as of June 7, 2020.

Figure 1. Grasshopper hatch (%) based on model simulations using current environmental conditions (blue bars) compared to long-term normal (red bars) as of June 7, 2020.
*LTN = long term climate normals, used for comparison of current year development (OBS)

Grasshopper hatch is predicted to be greatest across the southern prairies at this time (Fig. 2). Areas bound within the black line in the map illustrating hatch of the migratory grasshopper (M. sanguinipes) are areas where the predicted hatch is 35% or greater (Fig. 2).  This region includes most of south and central Saskatchewan (Fig. 2). 

Figure 2. Predicted percent of grasshopper (Melanoplus sanguinipes) population at hatching stage across
the Canadian prairies (as of June 7, 2020). 

The two graphs compare development of grasshoppers in Regina (Fig. 3) and Saskatoon (Fig. 4).  Model output indicates that 2nd instar nymphs may be present at Brandon, Lethbridge, Regina, Saskatoon and Winnipeg (Table 1). Third instar grasshoppers are predicted for Brandon, Regina and Winnipeg (Table 1).

Figure 3. Predicted grasshopper (Melanuplus sanguinipes) phenology at Regina SK.
Values are based on model simulations (April 1-June 7, 2020).

Figure 4. Predicted grasshopper (Melanuplus sanguinipes) phenology at Saskatoon SK.
Values are based on model simulations (April 1-June 7, 2020).

Biological and monitoring information related to grasshoppers in field crops is posted by Manitoba Agriculture, Saskatchewan Agriculture, Alberta Agriculture and Forestry, the BC Ministry of Agriculture and the Prairie Pest Monitoring Network.  Also refer to the grasshopper pages within the "Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide" (Philip et al. 2018) as an English-enhanced or French-enhanced version.

Cereal leaf beetle

Cereal leaf beetle (Oulema melanopus) - The CLB simulation model will be used to monitor this insect pest's development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of development stages based on biological parameters for this species. 

As of June 7, 2020, cereal leaf beetle (CLB) simulations indicate that oviposition continues and that 42% of the population is currently in the egg stage (Table 1).  Larvae are predicted to be in first, second and third instars (Table 1). The graph for Regina illustrates occurrence of first, second and third instar larvae (Fig. 1). The second graph demonstrates that development is slower around Grande Prairie (Fig. 2). 

Table 1. Predictive model output estimates for O. melanopus development (% of total population for each location) at selected sites across the Canadian prairies (as of June 7, 2020).

Figure 1. Predicted cereal leaf beetle phenology at Regina SK.
Values are based on model simulations (April 1-June 7, 2020).

Figure 2. Predicted cereal leaf beetle phenology at Grande Prairie AB.
Values are based on model simulations (April 1-June 7, 2020).

Manitobans - Dr. John Gavloski is looking for samples of cereal leaf beetle larvae this growing season to determine their range across Manitoba, their population density, and the rate at which larvae are parasitized. Please contact John.Gavloski@gov.mb.ca or @JohnTheBugGuy if you observe cereal leaf beetles in your fields. 

Canadians - Dr. Haley Catton is looking for samples of cereal leaf beetle larvae this growing season too!  Help her monitor for the tiny beneficial wasp, Tetrastichus julis, that lives inside the larvae of cereal leaf beetle.  Tracking these biological control agents will help Dr. Catton learn more about their distribution and value in fields.  Please check her Twitter poster for more details or contact her at @HaleyCatton or Haley.Catton@canada.ca . Access the recently released Pests & Predators podcast by Real Agriculture which features Dr. Haley Catton and this powerful parasitoid!

Lifecycle and Damage:

Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 3). 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 3. Adult Oulema melanopus measure 4.4-5.5 mm long (Photo: M. Dolinski).

Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the mid vein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching.  

Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 4).  When the larva completes its growth, it drops to the ground and pupates in the soil. 

Figure 4.  Larval stage of Oulema melanopus with characteristic feeding 
damage visible on leaf (Photo: M. Dolinski).

Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 - 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.

Fact sheets for CLB are published by the province of Alberta and available from the Prairie Pest Monitoring Network. Also access the Oulema melanopus page from the "Field crop and forage pests and their natural enemies in western Canada - Identification and management field guide" available as a free downloadable document in either an English-enhanced or French-enhanced version.

Alfalfa weevil

Alfalfa Weevil (Hypera postica) – Degree-day maps of base 9 °C are produced to predict the development of Alfalfa weevil (AAW) across the prairies.  The model is updated weekly to help growers time their in-field scouting for second-instar larvae. 

As of June 7, 2020, model output indicates that hatch of alfalfa weevil eggs is almost complete, as only 20% of the population is expected to currently be in the egg stage (prairie average). Prairie populations are predominantly in the first (29%) or second (36%) instar larval stages (Fig. 1) and approximately 15% are predicted to be third instar larvae (Table 1; Fig. 2). Developmental rates should be greatest across southern Manitoba and southeastern Saskatchewan.

Table 1.  Predictive model output estimates for Hypera postica development (% of total population for each location) at selected sites across the Canadian prairie as of June 7, 2020.

Figure 1. Predicted percent of populations of alfalfa weevil (Hypera postica) in the second instar stage across

the Canadian prairies as of June 7, 2020. 

Figure 2 Predicted percent of populations of alfalfa weevil (Hypera postica) in the third instar stage across

the Canadian prairies as of June 7, 2020. 

Monitoring

The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer” (Fig. 3, lower left).  The green larva featuring a dorsal, white line down the length of its body has a dark brown head capsule and will grow to 9 mm long (Fig. 3, upper right).  

Figure 3.  Developmental stages of the alfalfa weevil (Hypera postica); overwintered adult (upper row L-R), eggs, larvae, larva feeding or "skeletonizing" alfalfa leaf (lower row L-R), pupa within lacey cocoon, pupa, and newly emerged adult.

Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon).  Additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from the "Field crop and forage pests and their natural enemies in western Canada - Identification and management field guide" (Philip et al. 2018). The guide is available as an English-enhanced or French-enhanced version.

Predicted wheat midge development

Wheat Midge (Sitodiplosis mosellana) – Wheat midge overwinter as larval cocoons in the soil. Soil moisture conditions in May and June can have significant impact on wheat midge emergence. Adequate rainfall promotes termination of diapause and movement of larvae to the soil surface where pupation occurs. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Elliott et al. (2009) reported that wheat midge emergence was delayed or erratic if rainfall did not exceed 20-30 mm during May. Olfert et al. (2016) ran model simulations to demonstrate how rainfall impacts wheat midge population density. Our wheat midge model (Olfert et al. 2020) indicates that dry conditions may result in: 
    a. Delayed adult emergence and oviposition.
    b. Reduced numbers of adults and eggs.

Wheat midge model runs indicate that recent rainfall in Alberta has resulted in movement of more than 50% of the larval population to the soil surface (Fig. 1). Dryer conditions in Saskatchewan and Manitoba have delayed movement of larvae to the soil surface (Fig. 1). If dry conditions persist, this may delay pupation and adult emergence.  

Figure 1. Predicted  percent of larval population of wheat midge (Sitodiplosis mosellana) at soil surface across
the Canadian prairies (as of June 7, 2020).

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry).  A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.  

Alberta Agriculture and Forestry has a YouTube video describing in-field monitoring for wheat midge.  

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.

Predicted pea leaf weevil development

Pea Leaf Weevil (Sitona lineatus) –  As of June 7, 2020, the PLW phenology model indicates that females continue to lay eggs. The following two graphs illustrate the pattern of PLW oviposition for Swift Current and Lacombe. 

Figure 1. Predicted pea leaf weevil (Sitona lineatus) phenology at Swift Current SK.
Values are based on model simulations (April 1-June 7, 2020).

Figure 1. Predicted pea leaf weevil (Sitona lineatus) phenology at Lacombe AB.
Values are based on model simulations (April 1-June 7, 2020).

Link here to access photos of PLW and related species of weevils which can all be active simultaneously in Canadian prairie field crops. 

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.

Also refer to the pea leaf weevil page within the "Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide" - both English-enhanced or French-enhanced versions are available. 

Field Heroes

The Field Heroes campaign continues to raise awareness of the role of beneficial insects in western Canadian crops. Check the recently updated Field Heroes website for scouting guides, downloadable posters, and videos. Learn about these important organisms at work in your fields!  

Real Agriculture went live with a weekly Pest and Predators podcast series!
• Access Episode 1 - Do you know your field heroes?
• Access Episode 2 - An inside look at the Prairie Pest Monitoring Network.
• Access Episode 3 - How much can one wasp save you?

Access ALL the Field Heroes links here and be sure to follow @FieldHeroes!

Provincial Insect Pest Reports

Provincial entomologists provide insect pest updates throughout the growing season so plan to link to their upcoming information: 

• Manitoba's Crop Pest Updates for 2020 are available. Access the June 3, 2020 report. The summary indicates there have been reports of flea beetle damage to canola, and cutworms in various crops, from all agricultural regions. Grasshopper nymphs are emerging; most are still in the first instar stage.

• Saskatchewan's Crop Production News and read:
Issue 2 which includes articles on How to take good photos while out in the field, and a description of a peculiar little red bug, Peritrechus convivus.

Issue 1 which includes articles on Pest Monitoring in Saskatchewan - how and why, Early-Season Scouting of Cutworms, Flea Beetles in Canola, plus Pea Leaf Weevil Season Is Starting Soon.

•  Alberta Agriculture and Forestry's Agri-News occasionally includes insect-related information. Read about overwintered canola and ground beetles.