Story Posted: June 16, 2010

Insect Monitoring Update, June 16, 2010

This week's insect update includes: Diamondback Moths, Grasshoppers, Wind Trajectories, and Cutworms. There is no update on degree-day accumulations for bertha armyworm this week.

Bertha Armyworm (Mamestra configurata)
David's away this week so unfortunately we don't have an update on degree-day accumulations for bertha armyworm.

Diamondback moth (Plutella xylostella)
We've previously mentioned the bio-climate model for diamondback moth and our interest in using the model to predict the risk to canola due to increased population levels from multiple generations. The model was initialized with three start dates May 1, 15 and 30 (e.g. dates when adults arrived on the prairies). Last week we showed you what the potential for multiple generations was using Long-Term-Normal weather data to extrapolate into the growing season.

This week, Ross has provided a table that shows the projected date of occurrence of the 3rd generation (after arriving adults) using archived weather data from a warmer growing season (2008 in this example). Using the warmer summer temperatures of 2008, the model predicted that 3rd generation (after adults arrived on May 1) could occur by the first week in August at a number of locations across the prairies (see below). For the adults that arrived later (May 15, May 30) the predicted average dates of the 3rd generation were August 15 and 25, respectively. As was indicated last week, cooler conditions in 2010 (so far) could result in the 3rd generation occurring in late August (after May 15 arrival date).

However, the timing of this 3rd generation might still be an issue if the later seeding dates and slower crop development results in later crop maturity. By the way, Lloyd Dosdall indicated that their collections of diamondback moth in AB also included the parasitoid Diadegma insulare. This is good news. It is anticipated that parasitoid populations will also increase with the turnover in generations during the summer.

	Bio-Fix Date Location 1-May 15-May 30-May Brandon 11-Aug 22-Aug 25-Aug Calgary 23-Aug 30-Aug   Carman 8-Aug 12-Aug 22-Aug Dauphin 12-Aug 16-Aug 26-Aug Edmonton 16-Aug 23-Aug   Estevan 9-Aug 14-Aug 24-Aug Fairview 7-Aug 15-Aug 1-Sep Fort Vermilion     1-Sep Grande Prairie 8-Aug 15-Aug   High Level 8-Aug 17-Aug   Kindersley 6-Aug 13-Aug 23-Aug Lethbridge 10-Aug 14-Aug 24-Aug Manning 5-Aug 9-Aug 29-Aug Maple Creek 9-Aug 14-Aug 25-Aug Medicine Hat 2-Aug 6-Aug 17-Aug Melfort 12-Aug 19-Aug   Melita 11-Aug 15-Aug 26-Aug North Battleford 8-Aug 13-Aug 27-Aug Prince Albert 10-Aug 15-Aug 29-Aug Red Deer 14-Aug 25-Aug   Regina 9-Aug 14-Aug 25-Aug Rosetown 6-Aug 12-Aug 22-Aug Saskatoon 8-Aug 13-Aug 25-Aug Scott 9-Aug 15-Aug 31-Aug Swan River 17-Aug 22-Aug   Swift Current 8-Aug 13-Aug 23-Aug Val-Marie 6-Aug 12-Aug 21-Aug Average 9-Aug 15-Aug 25-Aug

Grasshoppers (Acrididae)
Our bioclimate model of the migratory grasshopper suggests that grasshopper hatch and development is progressing in a number of southern areas, most notably southern Manitoba (see below). As of Monday, June 14th, the model predicted that about 90% of the eggs have hatched in the Carman area. In relation to grasshopper development, 11 of the 25 sites are predicted to have some 3rd instar hoppers appearing this week.

	Location mean % Hatch mean % 3rd-Instar Brandon 73.3 7.1 Calgary 13.7 0 Carman 90.4 17.1 Dauphin 75.6 8.1 Edmonton 37.1 0 Estevan 75.4 8.3 Fairview 37.1 0 Fort Vermilion 75.6 12.1 Grande Prairie 37.1 0 High Level 37.1 0 Kindersley 38.5 0 Lethbridge 38.5 5.2 Manning 38.2 0 Maple Creek 38.5 0 Medicine Hat 66.3 5.6 Melfort 33 0 Melita 75.6 6.6 North Battleford 75 9.2 Prince Albert 38.5 0 Red Deer 16.3 0 Regina 33 0 Rosetown 38.5 5.2 Saskatoon 38.5 5.1 Scott 37.1 0 Swan River 38.5 0 Swift Current 16.3 0 Val-Marie 38.2 0

Wind Trajectories
We've mentioned the above-average number of southerly wind parcels that arrived over the prairies this spring, accompanied by the influx of diamondback moth adults. The two other crop pests of research interest in this project are leafhoppers (vectors of Aster Yellows disease) and cereal rust diseases. So if you observe high numbers of leafhoppers while out in the field, or Aster Yellows symptoms, please contact Chrystel Olivier; Chrystel.Olivier@agr.gc.ca. And I'm sure Kelly Turkington would appreciate hearing incidence reports of cereal rust diseases as well: Kelly.Turkington@agr.gc.ca.

Cutworms (Lepidoptera: Noctuidae)
Once again this growing season, there have been a number of reports of cutworm damage to crops across the Great Plains, both in Canada and the USA. There's a good overview of the issue in the Canola Council's website. Click to read the Cutworm Watch info in the Canola Council website.

As was mentioned last year, the pest complex of cutworm species appears to be expanding, or shifting in some cases. The most frequently encountered in field crops and grasses include Redbacked cutworm (Euxoa ochrogaster), Pale Western cutworm (Agrotis orthogonia), Army cutworm (Euxoa auxiliaries), Dingy cutworm (Feltia jaculifera), and Glassy cutworm (Apamea devastador). Although there are distinct differences between species in colour, shape and size of the adults and the larvae, the smooth-skinned larvae are most easily recognized by the way they typically curl up when disturbed. You may need to collect the larvae and rear them out to confirm the identification of the species involved. There are a number of natural enemies of cutworms and, if you're rearing larvae for identification purposes, you are also likely to collect emerging parasitoids if present in the population. Here's a reference that may be of interest: Turnock et al. 1993. Species and abundance of cutworms (Noctuidae) and their parasitoids in conservation and conventional tillage fields. Agriculture, Ecosystems & Environment 45: 213-227.

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