Monitoring of colorado potato beetle (Leptinotarsa decemlineata Say) sensitivity to insecticides

Abstract

Sensitivity of two field populations of Colorado potato beetle (Leptinotarsa decemlineata Say.) - CPB (Vilovo and Čurug) adults to insecticides were determined in 2008 and 2012. Bioassay was performed using screening test that allows rapid assessment of sensitivity of over wintered adults to insecticides. Sensitivity to four insecticides commonly used for CPB control in Serbia (chlorpyrifos, cypermethrin, thiamethoxam and fipronil) was assessed. Insecticides were applied at label rates, and two, five and 10 fold higher rates by soaking method. Insect mortality was assessed after 72 h. Sensitivity was assessed using a modified IRAC method (2009) and 1-5 scale. In 2008, both tested CPB populations were resistant to chlorpyrifos label rate, as well as in 2012. Both tested populations were also resistant to cypermethrin in 2008, while in 2012, population from Vilovo was resistant, and population from Čurug was moderately resistant. Significant differences in CPB sensitivity to thiamethoxam between populations tested in 2008 and 2012 were recorded.