Saturday, 10 August 2019

Predicted grasshopper development (August 8, 2019; Wk 18)

Grasshopper Simulation Model Output – Recent, warmer temperatures have resulted in increased grasshopper developmental rates. Surveys in central SK (last week) indicated that grasshopper populations are primarily in the fifth instar and adult stages and in some areas C. pellucida are very abundant. Based on model runs, approximately 50% of the population should be in the adult stage (24% last week). Based on climate data, 60% of the population would be expected to be in adult stage. Model output indicates that oviposition has begun in southern areas prairies. 

The first map (Fig. 1) indicates the average instar for grasshopper populations across the prairies with most areas have grasshopper populations that are in the 5th and adult stages. The second map (Fig. 2) indicates adult populations are developing across areas between 49 and 52 degrees North. The last map (Fig. 3) provides an overview of where oviposition is predicted to have started. The yellow and red areas show that oviposition has began across southern MB, southeastern SK and southern AB.

Figure 1. Predicted development stages of grasshopper (Melanoplus sanguinipes) populations across
the Canadian prairies (as of August 5, 2019). 

Figure 2. Predicted percent of grasshopper (Melanoplus sanguinipes) populations attaining adult stage across 
the Canadian prairies (as of August 5, 2019). 

Figure 3.  Predicted overview of where oviposition has started (as of August 5, 2019).

The Insect of the Week's Doppelganger featured GRASSHOPPERS for Week 14!!  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.