Sublethal effects of fenoxycarb on female reproduction in Helicoverpa armigera (Lepidoptera: Noctuidae)

Abstract

Abstract The cotton bollworm, Helicoverpa armigera (Hünber) (Lepidoptera: Noctuidae), is a polyphagous pest that causes severe damage to economical crops in most parts of the world. The juvenile hormone analogues are a group of insect growth regulators that increase larval ages and disrupt larval development. Moreover, they affect reproductive system in adult insects. In this study, the effects of sublethal doses of fenoxycarb on fecundity, fertility, and longevity parameters, as well as on oocyte size, ecdysteroid titer in ovaries, and expression level of the ultraspiracle (USP), ecdysone receptor (EcR), hormone receptor 3 (HR3), and vitellogenin (Vg) genes in adult female H. armigera, were examined. Feeding on artificial diet containing fenoxycarb (LC10 and LC25) significantly decreased the percentage of larval survival rate, pupation rate, pupal weight, fecundity, fertility, and oviposition period. It also clearly shortened female longevity. Fenoxycarb treatment suppressed the expression of the USP, EcR, and Vg genes in H. armigera but had no effect on the HR3 gene expression level in either pupae or adults. Overall, our results show that using fenoxycarb as a juvenile hormone analogue can reduce reproduction in H. armigera and may work as an alternative to the use of insecticides for controlling this important agricultural pest.