Story Posted: June 03, 2010

Insect Monitoring Update, June 3, 2010

Many areas of the prairies received a significant amount of precipitation this past month. The cooler, wet weather should help to moderate the activities of one major insect pest, namely grasshoppers.

1. Wind Trajectories
Agriculture & Agri-Food Canada and Environment Canada continue to assess the potential of wind trajectory models to predict possible movement and distribution of invasive alien species such as diamondback moth and plant diseases such as rusts in cereal crops. The goal is to provide an early-warning system for the arrival of these migratory insects and plant disease spores into Canada. Diamondback moths do not usually overwinter in Canada and arrive here each spring carried on air currents from sources of infestation in southern North America. If diamondback moth adults arrive early in the spring the possibility exists that several generations will be produced in a growing season, resulting in numbers high enough to cause damage to canola and other crucifer crops. Pheromone-baited traps are set out each year across the prairies to monitor moth populations and to assess the correlation between moth numbers and wind trajectories.

A wind trajectory describes the path followed by an air parcel as it is affected over time by horizontal and vertical wind fields in the atmosphere. Two types of trajectories are modeled in this project, reverse trajectories and forward trajectories. A reverse trajectory models the path of an air parcel from a particular destination in Canada backward over the previous five days to a source site in the Pacific Northwest (USA) or to a source in southern Texas and Mexico where pest numbers may be high. A forward trajectory predicts the possible path of air parcels from potential pest source areas in Mexico, the southern United States, or the Pacific Northwest to their final destination five days later.

In early May 2010, results indicated that a significant number of air parcels, coupled with rainfall, arrived over the prairies from the southern USA and Mexico. Most recently, (May 23 – 30) a large number of trajectories crossed over eastern SK and southern MB from Texas (see Carman, May 25, example below).

2. Diamondback Moth
Diamondback moth adults have been reported in pheromone traps from all three prairie provinces for several weeks now. Based on a review of pheromone lures and trapping protocols, conducted by Dr. Evenden's group at that University of Alberta, we revised our protocols for this season. We switched to using grey rubber septa (lures) and lowered the height at which the traps were located (50 cm above ground level or at crop canopy level). In MB, John reported a number of locations that have recorded adult catches (e.g. 137 moths at Landmark, MB). In SK, Scott Hartley reported that traps in southern Saskatchewan have been collecting low numbers of adults since mid-May. A trap near Avonlea, for example, has caught >70 diamondback moths to date, indicating there has been a significant influx of the pest in that area. In AB, Scott Meers reported that adults have been captured in a significant number of their sentinel sites as well. To date, the highest traps counts have been in the Cardston, AB area. As a result, it is recommended that producers include scouting for diamondback moth larvae in cruciferous crops this spring.

3. Flea Beetles
Bob Elliott reported that large numbers of crucifer and striped flea beetles were collected from canola stubble in mid-May and the last week of May, in the Saskatoon area. When conditions were calm and temperatures exceeded 15° C, 20 sweeps over volunteer canola plants netted approximately 50-100 beetles. Striped flea beetles were the predominant species collected in mid-May whereas crucifer flea beetles were the predominant species in early June. Due to the above-average precipitation that has accumulated this spring, Bob and his group have been interested in the potential impact that this excess moisture may have had on the efficacy of canola seed dressings. In replicated laboratory bioassays, Bob has found that neonicotinoid seed treatments provided poor flea beetle control (10-50% mortality after 72h) when the soil was fully saturated.

4. Grasshoppers
Grasshopper forecasts (below) are based on estimates of adult grasshopper density obtained from an annual survey implemented in the previous fall, as well as on weather and biotic factors that affect grasshoppers. Grasshopper populations tend to be higher in the warmer zones of the prairies. Heat in late summer and fall encourages mating and egg-laying. A warm, dry fall enhances egg development and a warm, dry spring increases survival of the hatchlings and the potential for subsequent damage to crops. From our egg collections in the fall of 2009, it appears that egg maturity and viability were relatively low going into the winter. To date this spring, large regions of the prairies have experienced cool temperatures and above-average rainfall. This will reduce the risk of grasshopper damage in these areas for a couple of reasons. Grasshopper hatch and development are slowed, and mortality is increased. In addition, because the base temperature at which crops are able to develop is lower than that for grasshoppers, crop phenology will tend to outpace grasshopper development and feeding.

We've initiated our bio-climate grasshopper model once again in order to report weekly grasshopper development. The list of locations has been expanded to include 25 sites across western Canada. Warm conditions during the third week of May resulted in egg development to the point where first hatchlings began to appear in central and southern SK. Initial hatch occurred during the period of May 15-21 when temperatures were well above normal. Based on model output, approximately 20% of grasshopper eggs are predicted to have hatched as of May 31, 2010.

	Location %Hatch % 1st Instar % 2nd Instar Calgary 5.9 5.5 0.0 Carman 33.0 23.0 6.2 Dauphin 33.0 23.8 6.2 Edmonton 16.3 11.5 4.1 Estevan 38.2 21.5 9.7 Fort Vermilion 16.3 9.5 6.0 Grande Prairie 13.7 0.0 0.0 Halkirk 5.9 5.9 0.0 High Level 5.9 1.4 0.0 Kindersley 33.0 23.1 5.8 Lethbridge 16.3 15.2 0.0 Manning 5.9 5.0 0.0 Maple Creek 16.3 2.6 4.5 Medicine Hat 16.3 1.0 4.1 Melfort 16.3 11.0 5.0 Melita 16.3 10.3 5.9 North Battleford 38.5 8.3 16.6 Prince Albert 16.3 1.5 5.1 Red Deer 5.9 4.6 0.0 Regina 16.3 1.0 6.5 Rosetown 38.4 24.9 11.9 Saskatoon 38.2 26.4 11.8 Scott 16.3 9.5 5.5 Swan River 16.3 10.6 5.5 Swift Current 13.7 2.1 0.0 Val-Marie 15.6 12.7 0.0 Average 19.4 10.5 4.6

5. Western Forum on Pest Management (WFPM)
One of the suggestions brought forward at our insect monitoring meeting in March was to find a suitable website to archive the results of the annual insect monitoring programs. We are happy to report that WFPM has agreed to do this on our behalf and, thanks to the webmaster Kelly Turkington, the website now has a link titled Insect Pest Monitoring Network (http://www.westernforum.org/IPMNMain.html). In addition to the latest survey maps, the website also contains a compilation of up-to-date insect monitoring and scouting protocols. We encourage you to have a look at the website. Your comments and suggestions for improvements are most welcome.

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