Monitoring on Insecticide Resistance of the Brown Planthopper and the White Backed Planthopper in Asia

Abstract

Annual change in insecticide susceptibility of the long-range migrating rice insects, the brown planthopper (BPH) and the white backed planthopper (WBPH), monitored by topical application was reviewed covering temperate and tropical Asia. Monitoring in Japan revealed consistent increase in topical LD 50 of BPH for various insecticides during the period between 1967 and 1983 with small peak in 1979 and abrupt increase occurred in 1984 and 1985 with the highest peak ever observed, and then recovered to the 1979 level and remain unchanged to the present. The WBPH showed no obvious change until 1984 when marked increase in LD 30, especially for the organoosphates occurred and gradual increase still continues. In the tropics, recent data on BPH obtained from Vietnam, Thailand and Malaysia shows apparent development of insecticide resistance with remarkable increase in LD 50 as compared to the late 1970's data. Present level of insecticide susceptibility is close to those in temperate Asia. WBPH from those tropical zone also showed remarkable increase in LD 50 during the last two decades.