Friday 19 May 2017

Weekly Update (May 18, 2017; Wk 03) - Predicted Grasshopper Development (Olfert, Giffen, Weiss)

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 15, 2017, the predicted mean embryological development was only slightly ahead of last week at 66% (compared to 62% last week), and similar to long term averages (64%; Fig. 1). Although it is still early in the growing season, grasshopper hatch can vary across the prairies. For example, model output indicated that the hatch in Vauxhall AB was predicted to be about a week ahead of Saskatoon SK. As a result, timing of peak hatch could be 10-14 days earlier in Vauxhall than Saskatoon.

Figure 1.  Simulation model outputs mapped to predict the embryological development of Migratory grasshopper  (Melanoplus sanguinipes) eggs across the Canadian prairies as of May 15, 2017).

Reminder - The Prairie Pest Monitoring Network's 2017 Grasshopper Forecast Map (Fig. 2) was released in January.  While spring temperatures, soil moisture conditions, and precipitation can all have an impact on overwintered grasshopper eggs, growers in areas highlighted orange or red in the map below should be vigilant as nymphs begin to hatch this season.
Figure 2. Prairie Pest Monitoring Network's 2017 Grasshopper Forecast Map.

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