Toru Nagata

Recent Status of Insecticide Resistance of Long-Distance Migrating Rice Planthoppers monitored in Japan, China and Malaysia

Abstract Simultaneous monitoring on insecticide susceptibility of the long-range migrating rice planthoppers, brown planthopper (BPH), Nilaparvata lugens (Stal) and the white backed planthopper (WBPH), Sogatella furcifera (Horvath), was conducted in Japan, China (3 locations) and Malaysia by standardized topical application method on 10 insecticides in 2000. The LD 50 for the 2000 Japan BPH and WBPH coincided with those for the two China populations, but one of the China populations gave remarkably larger LD 50 for imidacloprid. The 2000 Malaysia population of WBPH gave LD 50 almost equal to those of the 2000 Japan WBPH.

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 LD50 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 LD30, 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 LD50 as compared to the late 1970s data. Present level of insecticide susceptibility is close to those in temperate Asia. WBPH from those tropical zone also showed remarkable increase in LD50 during the last two decades.