Friday 24 May 2019

Predicted grasshopper development (May 23, 2019; Wk 07)

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 21, 2019, predicted grasshopper egg development was 66% (63% last week) and is similar to long term average values (68%) (Fig. 1).  


Figure 1. Predicted grasshopper (Melanoplus sanguinipes) embryological development across
the Canadian prairies as of May 21, 2019. 

Figure 2.  Predicted percent of grasshopper (Melanoplus sanguinipes) population at first instar stage across
the Canadian prairies (as of May 21, 2019). 

Model runs for Grande Prairie (Fig. 3), Lethbridge (Fig. 4) and Saskatoon (Fig. 5) were projected to June 15, 2019.  Results for Lethbridge (Fig. 4) and Saskatoon (Fig. 5) indicated that eggs should begin to hatch this week. Hatch in the Peace River region is predicted to be approximately one week later. Results also indicated that initial hatch (less than 6%) should have occurred in southwest SK and southeast AB.


Figure 3.  Predicted status of Melanoplus sanguinipes populations near Grande Prairie AB as of  May 21, 2019.  



Figure 4.  Predicted status of Melanoplus sanguinipes populations near Lethbridge AB as of  May 21, 2019.  



Figure 5.  Predicted status of Melanoplus sanguinipes populations near Saskatoon SK as of  May 21, 2019.  

Reminder - The Prairie Pest Monitoring Network's 2019 Grasshopper Forecast Map was released in March.  Review all the current 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.