Insecticidal properties of a juvenoid, pyriproxyfen, on all life stages of the diamondback moth, Plutella xylostella (Lepidoptera: Yponomeutidae)

Abstract

A photo-stable juvenoid, pyriproxyfen, affected every life stage of Plutella xylostella at critical points in their development. Egg hatch was reduced by about 90% when eggs were treated at 0-1 d. Third instar larvae treated with the compound failed to pupate. At a dose of 100 ppm, supernumerary larvae were produced and most of the dead larvae showed abnormalities associated with the chimera form. Pupae formed at this higher dose were arrested in their development, and all died. Final instar larvae 7 d after treatment pupated successfully. However, adult eclosion was reduced to about 50% even at a low dose of 4 ppm. About 20% of treated pupae failed to eclose, but the rest were unaffected and eclosed normally. Following treatment of adults, egg production was reduced to 10 per female and these failed to hatch. Furthermore, adults placed in contact with pyriproxyfen in an acetone : canola oil formulation on aluminium foil produced eggs that failed to hatch, especially when eggs were at an early stage of development within the female at the time of treatment. Results indicate that a device treated with an appropriate formulation of pyriproxyfen to contaminate both sexes of P. xylostella adults and their eggs would be superior to methods of targeting larvae in control operations.