AN ON-FARM INSECTICIDE RESISTANCE TEST KIT FOR COLORADO POTATO BEETLE (COLEOPTERA, CHRYSOMELIDAE)

Test kits were developed to enable growers to assess insecticide resistance in Colorado potato beetle populations. Kits included tests for resistance to: carbofuran (Furadan(R) 4F), phosmet (Imidan(R) 50WP), esfenvalerate (Asana(R) 1.9EC), and a combination of esfenvalerate & piperonyl butoxide (Butacide(R) 8EC). Tests were petri dishes containing filter paper treated with a discriminating concentration of insecticide (i.e., kills susceptible beetles but not resistant beetles). Discriminating concentrations were determined by testing susceptible and resistant strains of beetle across a range of insecticide concentration. About 200 test kits were distributed during the summer of 1988. Results received indicate: 1) Michigan beetle populations were either susceptible or highly resistant to carbofuran, 2) phosmet resistance was more widespread than previously thought, 3) many populations showed moderate to high levels of resistance to esfenvalerate, and 4) adding piperonyl butoxide reduced resistance to esfenvalerate, in many, but not all populations. Resistance kits help growers determine if insecticide resistance is present in beetle populations (either prior to or after an insecticide application), and also generate data useful to research and extension personnel in documenting the extent and distribution of resistance.