As of June 28, 2020, the grasshopper model estimates that hatch is nearly complete (Table 1). The prairie average, is 77% (71% last week). The majority of the nymphal population is predicted to be in the first to third instars (Table 1; Fig. 1). This week, 5th instar nymphs are predicted to occur in some locations (Fig. 1). Across the prairies, populations are predicted to be 21, 22, 21, 23, 11 and 2% in egg, first, second, third, fourth and 5th instar stages, respectively (Table 1).
Table 1. Results of grasshopper simulation (Melanoplus sanguinipes) development as of June 28, 2020.
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| Figure 1. Predicted average instar stages of grasshopper (Melanoplus sanguinipes) populations across the Canadian prairies (as of June 28, 2020). |
Warmer conditions across southern regions of the prairies should result in rapid development of 1st to 3rd nymphs (Table 1). This week 5th instar nymphs are predicted to appear at Regina, Brandon and Winnipeg (Table 1). The two graphs compare development for Saskatoon (Fig. 2) and Winnipeg (Fig. 3). Grasshopper populations near Saskatoon are predominantly in the 2nd and 3rd instars (Fig. 2) while populations near Winnipeg are expected to be primarily 3rd and 4th instars (Fig. 3).
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| Figure 2. Predicted grasshopper (Melanuplus sanguinipes) phenology at Saskatoon SK. Values are based on model simulations (April 1-June 28, 2020). |
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| Figure 3. Predicted grasshopper (Melanuplus sanguinipes) phenology at Winnipeg MB. Values are based on model simulations (April 1-June 28, 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.
