Survey of susceptibility to registered and new insecticides in Canadian Colorado potato beetle (CPB), Leptinotarsa decemlineata Say, populations

The 2017 insecticide susceptibility survey in Canadian populations of Colorado potato beetle (CPB) determined that ten percent of the tested CPB populations were resistant to the neonicotinoid insecticide, TITAN™ (clothianidin). A further sixty percent of the populations could be considered to have reduced susceptibility to clothianidin. These results are not surprising as over 76% of the populations were collected from fields where neonicotinoid products have been applied within the past five years. Interestingly, over two thirds of populations tested with the butenolide product SIVANTO® PRIME (flupyradifurone), recently registered in Canada but not promoted for potato pest control, showed reduced susceptibility and resistance. The majority of CPB populations where reduced susceptibility or resistance to flupyradifurone was observed were also found to be resistant or less susceptible to clothianidin. Twenty nine percent of the 14 CPB populations tested with the new anthranilic diamide, tetraniliprole, were determined to be resistant and a further 57% were determined to have reduced susceptibility. In the cases where susceptibility to diamides was reduced or resistance was determined, a similar trend with clothianidin was observed. In some cases other diamide products had previously been applied at the same collection location or there was reduced susceptibility or resistance to other neonicotinoid products in the same populations. Based on the survey findings, cross-resistance between classes should be an issue of concern for potato growers in the coming season.