Excretion and metabolism of 14C-imidacloprid in resistant and susceptible Colorado potato beetles

Colorado potato beetle is one of the principal pests of potatoes in the US and many places in the world. Neonicotinoid insecticides are the main choice to control the Colorado potato beetle. However, CPB has developed resistance to these compounds and is ranked as the 4th more resistance species to insecticides in the world. In order to effectively manage resistance, it is necessary to determine the mechanism of resistance. The rate of excretion and metabolism of14C- imidacloprid in resistant beetles from Michigan and Long Island, NY was identified and compared with a susceptible strain. Adults of Colorado potato beetles were treated with 14C-imidacloprid via oral assays procedure that closely approaches the form in which beetles come in contact with imidacloprid in the potato fields. Metabolism, excretion and internal amount of 14C-imidacloprid at different times (1, 2, 4, 24, and 72 h) after application were determined. Resistant beetles from Michigan and Long Island, NY excreted and metabolized more 14C-imidacloprid than susceptible beetles. This was also correlated with high resistance levels to imidacloprid and underscores the importance of managing neonicotinoid resistance in potato beetles.