Effect of Selected Insecticides on Homalodisca coagulata (Homoptera: Cicadellidae) and Transmission of Oleander Leaf Scorch in a Greenhouse Study

Homalodisca coagulata</it> (Say) is a recent introduction to California. It is known to spread a strain of the bacterium Xylella fastidiosa</it> Wells, Raju, Hung, Weisberg, Mandelco-Paul & Brenner that induces oleander leaf scorch disease in oleander, Nerium oleander</it> L. Oleander leaf scorch is lethal to oleander and threatens to decimate one of the most important landscape shrubs in California. Towards developing a management strategy for H. coagulata</it>-spread oleander leaf scorch, we documented the affects of selected insecticides on H. coagulata</it> mortality, feeding behavior, and disease transmission in a greenhouse study. Oleanders treated with fenpropathrin, fenpropathrin + acephate, and imidacloprid caused significant mortality to caged H. coagulata</it> within 4 h of exposure. Within 24 h, these pesticides caused nearly 100% mortality 3 wk after treatment. In other experiments, acetamiprid and fenpropathrin treatments reduced time spent feeding and total time on plants. H. coagulata</it> on fenpropathrin-, acetamiprid-, and imidacloprid-treated oleander died in less than 13 min on average. Oleander leaf scorch transmission by H. coagulata</it> was blocked by applications of foliar-applied acetamiprid, and soil-applied imidacloprid and thiamethoxam.