Rainfastness and residual activity of insecticides to control Japanese beetle (Popillia japonica) in grapes

Japanese beetle (Popillia japonica Newman) is an invasive pest that poses substantial risks to growers of Grapes (Vitus spp.) in the Midwest. Damage by Japanese beetle adults mainly takes the form of mechanical damage on leaves, but they may also feed directly on the fruit. The purpose of this study was to determine the impact of precipitation and aging on the performance of insecticides on the Japanese beetle. Insecticides from five chemical classes were used in this study including: Phosmet, Carbaryl, Bifenthrin, Thiamethoxam, and Indoxacarb. Each insecticide was tested under three levels of rainfall: 0 cm, 1.27 cm, and 2.54cm and two levels of field aging: 24h and 7d. 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 and both levels of residue field age. Bioassays were also used to measure the repellent effects of the insecticides to Japanese beetle feeding.