Interaction between halofenozide and the entomopathogenic nematode Heterorhabditis marelatus for control of Japanese beetle (Coleoptera : Scarabaeidae) larvae

Japanese beetle, Popillia japonica Newman is a major pest of turf and ornam entals. Laboratory bioassays were conducted to evaluate the potential inter actions between a biological control agent, Heterorhabditis marelatus (Nema toda: Heterorhabditidae) IN strain and the insecticide halofenozide against both overwintered and nonoverwintered 3rd instars of Japanese beetle. Trea tments consisted of all combinations of 2 rates of halofenozid with H. mare latus nematodes Imidacloprid was used as a standard. Percentage larval mort ality was evaluated at 7, 14, and 21 d after treatment No deleterious effec ts were observed. The nematode treatments generally produced significantly greater larval mortality relative to both chemical treatments. Twenty-one c lays after treatment, both rates of nematodes resulted in 100% mortality, w hereas insecticide treatments did not surpass 60% mortality. No synergism w as detected in any of the combination treatments. There were no significant differences in nematode reproduction in larvae exposed to halofenozide and nematodes versus larvae exposed to only nematodes.