Mating time of the rice-feeding and water-oat-feeding strains of the rice stem borer, Chilo suppressalis (Walker) (Lepidoptera: Pyralidae).

The Rice Stem Borer, Chilo suppressalis (WALKER), is a serious pest of rice plants in Asia. In Japan, host plants of are mainly rice plants (Oryza sativa) and the water-oat (Zizania latifolia). Our previous study indicated significant differences in insecticide susceptibility and esterase isozyme patterns between the rice-feeding and water-oat-feeding strains. In the present study, the mating time of the two strains was investigated in the laboratory. The mating time was significantly different. The peak of mating time of the rice-feeder was 5 h earlier than that of the water-oat-feeder, suggesting that the two strains are reproductively isolated.