Effects of pyriproxyfen, insect growth regulator on reproduction of common cutworm, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae)

The effects of pyriproxyfen, a juvenile hormone mimic on the reproduction of the common cutworm, Spodoptera litura (Fabricius) were examined. Topical application of 0.1 ng of pyriproxyfen to day-1 female pupae and 0.125 mu g to day-0 6th stadium larvae reduced the total number of eggs oviposited and hatchability of oviposited eggs. The female adults to which 0.4 mu g pyriproxyfen was applied at the day-0 6th stadium did not show any abnormalities in morphological characteristics, adult life span and mating ability with untreated males. However, the total number of eggs oviposited and hatchability of oviposited eggs were lower in treated females than untreated ones. Female adults treated with 0.3 ng of pyriproxyfen at the day-1 pupal stage showed wing abnormalities. Ovarian development was also inhibited and about 40% of female adults showed morphological ovarian abnormalities. Female adults with no morphological ovarian abnormality oviposited fewer than untreated female adults and the hatchability of oviposited eggs was lower.