There is no information on parasitoids that attack larvae and pupae of the oriental corn borer Ostrinia furnacalis (OCB) in Japan. Larval and pupal parasitism of OCB infesting sweet corn was investigated in a field at Tsukuba, central Japan. Three larval and one pupal parasitoid species parasitized 31.0% and 2.9% of OCB larvae and pupae, respectively. The gregarious Braconid parasitoid Macrocentrus grandii was abundant and parasitized 15.7% of OCB larvae. The solitary Ichneumonid Temelucha sp. nr japonica was newly recorded as a major parasitoid (7.8%) of OCB larvae.
The insecticides susceptibility of adults of the water strider, Gerris latiabdominis, was studied. The water strider is quite susceptible to insecticides and the LD50 values of organophosphates, carbamates, pyrethroids, nereistoxins, and neonicotinoids ranged from 0.24 to 31.6μg/g. The LD50 values for fenitrothion, BPMC and PHC were low compared to those for several Hemipteran insect pests of rice paddy.