LAUSR

BACKGROUND The diamondback moth (DBM), Plutella xylostella (L.), is the most destructive pest of cruciferous vegetables worldwide. Chlorfenapyr is an important insecticide for controlling DBM. The impacts of three sublethal doses (LC1 , LC10 and LC30 ) of chlorfenapyr on the chlorfenapyr-exposed DBM individuals and their unexposed F1 and F2 offspring were investigated in order to reveal the non-lethal deleterious effects of chlorfenapyr and its potential hormetic effects. RESULTS LC1 significantly increased female pupa weight of F0 and F1 generations, and F0 fecundity as well as F1 gross reproduction rate (GRR). The LC1 -elicited rise in emergency rate and fecundity was significantly greater in F0 than in F1 . By contrast, LC30 significantly decreased age-specific survival rates, pupation rate, male pupal weight, emergence rate and fecundity of F0 and F1 generations as well as female adult proportion and GRR, net reproduction rate (R0 ), intrinsic rate of increase (rm ) and finite rate of increase (λ) of F1 generation. The LC30 -induced reductions in pupation rate, adult emergence rate, male and female pupa weight, and fecundity were greater in F1 than in F0 . While LC10 elicited only a mild inhibition (extension of pupal duration) in F0 , it yielded both deleterious (drops in female proportion and age-specific survivals) and hormetic effects (ups in male longevity and female fecundity) in F1 . CONCLUSION The results demonstrate that the sublethal effects of chlorfenapyr on DBM vary from inhibition to stimulatory hormesis, depending on the dose and generation. This article is protected by copyright. All rights reserved.