Colorado Potato Beetle insecticide resistance spreading west

It should come as no surprise to Prairie potato growers that Colorado Potato Beetle (CPB) insecticide resistance is increasing.

The trend of resistance to neonicotinoids (the Group 4 class of insecticides which includes Admire, Actara, Poncho and Calypso) has long been noted in Eastern Canada, and is now spreading west.

Ian Scott, a research scientist with Agriculture and Agri-Food Canada based in London, Ont., recently participated in a study monitoring CPB populations for resistance and cross-resistance with other insecticides. His team, he says, recently published a survey of neonicotinoid resistance in Canadian CPB populations in which they concluded that resistance to imidacloprid (Admire), the first neonic to be registered for CPB control, was present “in a significant number of populations.”

The study also notes decreasing susceptibility to one of the recently-registered products, thiamethoxam (Actara). “Resistance to the more recently registered neonicotinoids, thiamethoxam and clothianidin (Titan), is likely if the products are continuously used without proper insecticide resistance management (IRM) practices being applied,” Scott explains.

Perhaps most troublingly, the survey also demonstrated that cross-resistance is on the rise. Using comparisons of CPB mortality generated from lab bioassays with Admire, Actara and Titan, a positive, and significant, correlation indicated that there is potential for cross-resistance between these three neonics.