Decrease in Susceptibility to Organophosphorus and Carbamate Insecticides in the Brown Planthopper, Nilaparvata lugens STÅL (Homoptera: Delphacidae)

Abstract

Insecticide susceptibility of the brown planthopper collected annually from Takehara, Hiroshima Prefecture, in August and October since 1970 was monitored using the topical application method. The results indicated that susceptibility to organophosphorus insecticides and to carbamate insecticides in the brown planthopper had increased since 1973 and 1979, respectively. Local differences in insecticide susceptibility among 7 populations collected from 6 localities in Hiroshima Prefecture in 1979 were negligible. In the 1981 survey, no significant local difference in insecticide susceptibility was detected. Laboratory selection with diazinon using the spray method in the brown planthoppers collected from Takehara in 1970 caused a marked decrease in susceptibility to this insecticide, whereas selection with carbaryl in the same population caused no change in susceptibility to carbaryl. On the basis of the results obtained, extreme reduction in the susceptibility to organophosphorus insecticides in the brown planthopper can be expected. When the brown planthoppers collected from Takehara in 1975 were selected using applications of BPMC and fenitrothion, each selection resulted in a decrease in susceptibility to both BPMC and fenitrothion.