Thursday, 4 June 2020

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 31, 2020, predicted embryonic development was 78% compared to 73% last week (Table 1). Grasshopper egg development is currently 8% greater than long term average values (Fig. 1). 

Table 1.  Predictive model output estimates for Melanoplus sanguinipes populations at selected sites across the Canadian prairie as of May 31, 2020.

Figure 1. Grasshopper hatch (%) based on model simulations using current environmental conditions (blue bars) compared to long-term normal (red bars) as of May 31, 2020.
*LTN = long term climate normals, used for comparison of current year development (OBS)

This week, the simulation estimates that hatch is underway (Fig. 2). The prairie average for hatch, is 7% (compared to 3% last week). Grasshopper hatch should be greatest in across the southern prairies at this time, based on the phenology model (Fig. 2). This includes most of south and central Saskatchewan (Fig. 2).  

Figure 2. Predicted percent of grasshopper (Melanoplus sanguinipes) population at hatching stage across
the Canadian prairies (as of May 31, 2020). 

Biological and monitoring information related to grasshoppers in field crops is posted by Manitoba AgricultureSaskatchewan AgricultureAlberta 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.