Story Posted: June 23, 2010

Insect Monitoring Update, June 23, 2010

Greetings! It’s been a week of extreme weather with far too much rain throughout most of the prairies and hot and dry in the Peace! Over the past seven days heavy rainfall events were reported across southwest Saskatchewan and southern Alberta.

Some stations reported more than 150 mm. Conversely, conditions remain very dry in northwestern Alberta and into the BC Peace. http://www.agr.gc.ca/pfra/drought/prrl7dy_e.htm

Over the past 30 days conditions have been 150-200% wetter than normal across most of MB, SK, and AB. The Peace River area has been much dryer than normal with rainfall amounts that are less than 40% of normal.

	Figure 1. Accumulated precipitation the past 30 days for the prairie region.

Diamondback moth (Plutella xylostella)
Traps throughout the prairies continue to collect adults over the past 10 days. Sites in Manitoba recorded counts ranging up to 78 per trap although most sites had counts <20 per trap through the province. In Saskatchewan, moth counts have been highest in the south but traps near Saskatoon have also collected moths. In Alberta, traps collected up to 73 moths near Bonnyville while an average count of 7 moths per trap was observed throughout the province.

At this point in the season, watch for windowing on canola leaves caused by Diamondback larvae which are very green in colour and feed primarily on the undersides of leaves. Larvae, when disturbed, will drop down from a leaf suspended from a single silk thread. The green larvae also squiggle in a somewhat characteristic fashion when dislodged from a plant.

Cutworms (Lepidoptera: Noctuidae)
Cutworms have been reported in canola fields from Central Alberta and throughout the Peace region with several acres suffering heavy infestations (e.g., 4-8 larvae/m2) and considerable damage requiring insecticide application or even re-seeding. Up to five different species of noctuid larvae have been collected from canola fields in the Peace with the majority of them now confirmed as Dingy cutworms. Dingy and Bristly cutworms have been reported in
Saskatchewan in canola.

Bertha armyworm (Mamestra configurata)
The degree-day accumulations for predicted emergence of Bertha armyworm adults in 2010 is ahead of 2009 despite the incredible rain that has fallen over most of the prairies this week.

	Figure 2. Degree-day accumulations for predicted emergence of adult Bertha armyworm in 2010.

Reminder: Please plan for pheromone traps to be deployed now or in the very near future so the initial moths can be monitored. Remember, use gloves when installing the pheromone lures and when installing the insecticidal strip that sits in the bottom of the Unitrap.

Please note that the pheromone traps can collect other species of moths in addition to Bertha armyworm moths. The following photos and text have been generously copied from “Guide to Bertha armyworm monitoring – 2008” produced and circulated by Saskatchewan Ministry of Agriculture:

There are two common contaminant moths occurring in pheromone traps. Moths from the genus Agroperina are a chestnut brown moth with a hairy body; these moths are about the same size as a Bertha armyworm moth. Moths from the genus Leucania are a cream-coloured moth somewhat smaller than a Bertha armyworm moth. Neither of these are considered crop pests. Refer to the photo below - The true colours of the moths are faded due to the pinning process, however, the pattern of the wings remains the same.

Grasshoppers (Orthoptera: Acrididae)
Only five or six grasshopper species of the 80+ that occur on the prairies are regarded as crop pests. The lifecycles of these six economically important species are similar. Nymphs hatch from overwintered eggs in the spring. Nymphs develop through five stages or instars before becoming adults. The life stages of the two-striped grasshopper (Melanoplus bivittatus) are shown below. Note that adults possess fully formed wings that extend the entire length of the abdomen.

As of June 21, the model predicted that 36% of the eggs had not yet hatched. Approximately 60% of the population is between first and third instar. The model predicts that by next week 10% of the population should be in the fourth instar.

	Location Average of % Egg Average of % First - Third Brandon 11.9 83.2 Calgary 80.8 19.2 Carman 0.2 78.1 Dauphin 17.9 72.8 Edmonton 64.0 36.0 Estevan 18.1 73.5 Fairview 27.1 72.9 Fort Vermilion 5.3 88.3 Grande Prairie 56.5 43.5 Halkirk 84.0 16.0 High Level 35.8 64.2 Kindersley 70.2 29.8 Lethbridge 19.5 80.5 Manning 32.7 67.3 Maple Creek 43.9 56.1 Medicine Hat 24.5 75.5 Melfort 26.3 73.7 Melita 11.5 82.3 Prince Albert 21.0 79.0 Red Deer 75.5 24.5 Regina 25.1 74.9 Rosetown 14.2 85.8 Saskatoon 13.4 86.6 Scott 25.0 70.8 Swan River 57.3 42.7 Swift Current 92.5 7.5 Val-Marie 27.5 72.5 Average 36.4 61.4

Pea leaf weevil (Sitona lineatus)
The distribution of this insect pest includes southern Alberta and southwest Saskatchewan.

Overwintered weevils seek out and feed upon cultivated and wild legume species early in the spring. While Pea leaf weevils cause economic damage in peas, they also feed upon dry bean, faba bean, lentil, and seedling alfalfa plants. Overwintered adults emerge early in the spring and females lay eggs from May to June. Look for characteristic notching on pea leaves.

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