抄録
The study of the effects of insect growth regulators (IGRXs) (hydroprene and R-20458) on the development and morphogenesis of the female Rice weevil, Sitophilus oryzae (Coleoptera : Curculionidae) was conducted in IGR-treated wheat and by topical application. All develop-mental stages were found to be susceptible to some degree to the IGRs in both treatments, the 4th larval and pupal stages being the most susceptible. FX1 progeny production was completely suppressed in IGR-treated wheat. Although the IGRXs did not produce morphological abnormalities in younger larvae, they had a direct toxic effect on some of these insects treated topically. In general, the IGRs caused ecdysial failures, metamorphic defects, and morphogenetic abnormalities at larval-pupal molts. Some of the treated insects emerged as apparently normal adult rice weevils. Thus, although the IGRs disrupted the molt cycle, the ecdysial failures produced were not always lethal. In addition, these compounds induced uneven pigmentation and sclerotization, and produced malformed dlytra and folded or crumpled hindwings in treated weevils. Hydroprene and R-20458 prevented differentiation of the ovaries at metamorphosis. This interfered with the normal development of the oocytes and resulted in the formation of atrophied oocytes. Of the two IGRs, hydroprene was more offective against the rice wevil than R-20458.
