Development of Insecticide Resistance by the Brown Planthopper, Nilaparvata lugens STÅL (Hemiptera: Delphacidae) and Resistance Pattern of Field Populations

Abstract

Lethal doses of insecticides were assayed in several populations collected in the field in Kagawa and Kagoshima Prefectures, from 1967 to 1979, and Ali-esterase (esterase hydrolyzing β-naphthyl acetate) activity of two populations collected in the field in Kagawa Prefecture in 1968 was determined by agar-gel electrophoresis. The LD₅₀ values of BHC, organophosphorus and carbamate insecticides were slightly higher in three populations collected in the field in Kagawa Prefecture than in the K population collected in the field in Kagoshima Prefecture in 1967 or in 1969. The Ali-esterases of the brown planthopper were separated into five bands by agar-gel electrophoresis. The ratios of individuals with high and medium esterase activity of the E₂ band ranged from 12 to 22% and from 15 to 19%, respectively. These results suggest that some individuals with organophosphate-resistance (R-op) were produced in the brown planthopper populations during the period 1967-1969. The development of R-op was very slow during 1967 to 1972. A relatively large increase of the R-op level was observed in 1975. Thereafter, the R-op level increased gradually each year and the T and the 0t populations collected in the field in Kagawa Prefecture in 1979 were highly resistant to fenthion (30- to 32-fold), fenitrothion (22- to 23-fold), cyanofenphos (145- to 423-fold) and malathion (20- to 31-fold). The development of carbamate resistance in the brown planthopper was slower than that to fenthion-, fenitrothion- or malathion. The T population collected in the field in Kagawa Prefecture in 1979, however, became 5- to 18-fold resistant to almost all the carbamate insecticides tested. It was shown that the brown planthopper had developed multiple resistance to organophosphorus and carbamate insecticides, although it was susceptible to natural pyrethrins and organophosphorus fungicides, IBP and edifenphos like the LE strain.