Thursday, 11 July 2019

Predicted grasshopper development (July 11, 2019; Wk 14)

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).

Cool temperatures continue to result in reduced grasshopper development rates. Populations are developing into third and fourth instars. Based on model runs, approximately 13% of the population is in the first instar, 23%  is predicted to be in the second instar, and 32% is in the third instar, 21%  are predicted to be in the fourth instar and l4% may be in the fifth instar. Grasshopper development this season has been similar to long term average development. The following map (Fig. 1) indicates that grasshopper populations across the southern prairie are mostly in the third instar. Compared to last week development has increased across southern regions of the prairies. Grasshopper development has been greatest near Winnipeg MB.
Figure 1. Predicted development stages of grasshopper (Melanoplus sanguinipes) populations across
the Canadian prairies (as of July 8, 2019). 

This week, the Insect of the Week's Doppelganger features GRASSHOPPERS!!!  Check out the excellent nymph photos to help your in-field scouting!

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" which is available as a free downloadable document in either an English-enhanced or French-enhanced version.