Mating Time of the Rice-feeding and Water-oat-feeding Strains of the Rice Stem Borer, Chilo suppressalis(Walker) (Lepidoptera: Pyralidae).

Abstract

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 5h earlier than that of the water-oatfeeder, suggesting that the two strains are reproductively isolated.

Genetic differences between rice and water-oat feeders in the rice stem borer, Chilo suppressalis (Walker) (Lepidoptera: Crambidae)

“…We used a rubber septum containing synthetic pheromone (Shin-Etsu Chemical Co., Ltd., Japan) that was placed at the center of a sticky plate (240 mmϫ250 mm, Takeda Chemical Industries Co., Ltd., Japan) as a pheromone trap. Konno and Tanaka (1996b) and Samudra et al (2002) reported that the mating time differed between the two feeders under laboratory conditions, and if this was the case in our study populations, the sizes and gene frequencies could be differentiated between the trap periods corresponding to different mating activities between the two feeders. Therefore, we collected trapped moths at both midnight and early morning: the traps were set before sunset, the trapped moths (hereafter, first trap samples) were gently collected alive at 1:00 am, a new sticky plate with the pheromone was left until the next morning, and the moths trapped on the new plate (hereafter, second trap samples) were collected in the early morning.…”

“…Observation of mating time under laboratory conditions. Equal numbers of male and female adults (1 d post-emergence) of the two feeders (6-10 pairs) were released at least 1 h before the beginning of the scotophase in a cage covered with fine mesh (300 mmϫ300 mmϫ300 mm), as reported by Konno and Tanaka (1996b). Laboratory conditions were kept constant (15L : 9D, 25Ϯ1°C) for observation.…”

“…However, Konno and Tanaka (1996a) showed significant differences between the two feeders in insecticide susceptibility and activity of the aliesterase isozyme using moths collected in Okayama Prefecture. They also observed a clear difference in mating time between the two feeders under laboratory conditions: rice feeders mostly mated during the first half of the scotophase, while water-oat feeders mated during the late scotophase in moths from Okayama Prefecture (Konno and Tanaka, 1996b). These findings suggest that there could be a certain reproductive barrier between the two feeders.…”

Polymorphic microsatellite loci for the rice stem borer, Chilo suppressalis (Walker) (Lepidoptera: Crambidae)

“…Maki and Yamashita, 1956;Takasaki et al, 1969). Konno and Tanaka (1996a) observed a clear difference in the mating time between the two feeders under laboratory conditions: most rice feeder mating was observed during the first half of the scotophase, while that of water-oat feeders was observed during the late scotophase. Konno and Tanaka (1996b) also showed significant differences between the two feeders in insecticide susceptibility and activity of the aliesterase isozyme.…”

Morphometric differences between rice and water-oats population of the striped stem borer moth, Chilo suppressalis (Lepidoptera: Crambidae)

“…From these results, it has been considered that these two populations belong to a single species. Konno and Tanaka (1996) observed a clear difference in mating time in the laboratory between two populations collected from Okayama Pref. (Western Japan).…”