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 May 18, 2020, predicted embryonic development was 66% and is similar to long term average values.  Development was greatest in a region from Regina to Saskatoon and southwest to Lethbridge.  

Figure 1. Grasshopper embryological development (%) based on model simulations using
current environmental conditions (May 18, 2020).

Embryonic development at Winnipeg, Brandon and Grande Prairie is expected to be seven to ten days slower than for Saskatoon, Swift Current and Lethbridge (Fig. 2). Based on these locations, Winnipeg (Fig. 2) was the only site with embryonic development predicted to be slower than long term average (Fig. 3).  

Figure 2. Grasshopper embryological development (%) based on model simulations using
current environmental conditions (as of May 18, 2020) for sites across the Canadian prairies.

Figure 3. Grasshopper embryological development (%) based on model simulations using current environmental conditions (blue bars) compared to long-term normal (red bars) as of May 18, 2020.
*LTN = long term climate normals, used for comparison of current year development (OBS)

This week initial hatch is predicted to occur in southern Alberta (Fig. 4). Across the prairies, results indicated that eggs should begin to hatch during the next two weeks (Fig. 4). 

Figure 4. Predicted percent of grasshopper (Melanoplus sanguinipes) population at first instar stage across
the Canadian prairies (as of May 18, 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.