Effects of low-risk insecticides against oriental flower beetle, Protaetia orientalis, in lab assays

Oriental flower beetle (OFB), Protaetia orientalis, is an established scarab beetle species in Hawaii. In Hawaii, it was first discovered on Oahu in 2002, and since then spread to neighbor islands. Adult beetles cause damages to various landscape plants and crops, such as coconut palm, mango, papaya, etc. At larva stage, OFB can cause physical damages to turfgrass roots while tunneling through soil, and can also be considered as a nuisance pest on golf courses because they push soil up onto putting green surface. In this research, we evaluated effects of several low-risk insecticides against OFB larvae in multiple lab assays, including: abamectin benzoate, acephate, azadirectin, cyclaniliprole, dinotefuran, emamectin, flypradifurone, imidacloprid, malathion, and Red Palm Weevil Killer (a.i.s. clove oil, thyme oil, sodium lauryl sulfate). Each insecticide was tested at low and high concentrations at 100 ppm and 500 ppm, respectively. Measurements on larvae health and mortality were made hourly during the first four hours on the first day, and then daily through 7 days post treatment. Our results showed that cyclaniliprole and acephate were the best treatments (>60% mortality at 3 days post treatment) and both resulted in significantly higher OFB mortality compared to the control. Dinotefuran also resulted in significantly higher OFB mortality compared to the control, but was not as effective as cyclaniliprole and acephate. The rest of the treatments were not effective except that imidacloprid resulted in moderate OFB mortality. We will continue evaluating field efficacies of cyclaniliprole, acephate, and dinotefuran against OFB.