Rainfastness of insecticides to control Japanese beetles (Popillia japonica) in blueberries

Japanese beetle (Popillia japonica Newman) is an invasive pest that poses substantial risks to growers of blueberries (Vaccinium spp.) in the Midwest. Damage by Japanese beetle adults mainly takes the form of mechanical damage on leaves and directly on the fruit. The purpose of this study was to determine the impact of precipitation on the efficacy of insecticides used to control Japanese beetle. Insecticides from four insecticide classes were used in this study including phosmet, carbaryl, zeta-cypermethrin, and imidacloprid. Each insecticide was tested under three levels of rainfall: 0 mm, 12.7 mm, and 25.4 mm. Field sites were sprayed and rainfall was simulated at the Trevor Nichols Research Complex in Fennville, MI. Bioassays were used to compare the lethal and sublethal effects of the five insecticides at each rainfall level. Preliminary experiments were also performed to look at leaching potential of these insecticides in soil appropriate for growing blueberries.