Thursday 2 May 2019

Predicted grasshopper development (May 2, 2019; Wk 04)

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).  


This week we observed an adult grasshopper (female), Arphia conspersa, in Saskatoon. Model runs were conducted for Grande Prairie, Saskatoon, Swift Current and Lethbridge.  

As of April 30, 2019, predicted development was 60% and is similar to long term average values. The following graph illustrates development for 4 prairie locations (Fig. 1). Hatch is expected to occur during the 3rd week of  May (Saskatoon, Swift Current and Lethbridge) and early June in Grande Prairie.
Figure 1.  Percent predicted embryological development of M. sanguinipes at Grande Prairie AB, Saskatoon SK, Swift Current SK, and Lethbridge AB as of April 30, 2019 (Weiss, Olfert, Vankosky [AAFC] 2019).


Reminder - The Prairie Pest Monitoring Network's 2019 Grasshopper Forecast Map was released in March.  Review all the risk and forecast maps by linking here.  While spring temperatures, soil moisture conditions, and precipitation can all have an impact on overwintered grasshopper eggs, areas highlighted orange or red in the 2019 forecast map should be vigilant this spring by performing in-field scouting to assess nymph densities.

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 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.