Sublethal effects of abamectin on the biological performance of the predatory mite, Phytoseius plumifer (Acari: Phytoseiidae).

Traditionally estimating pesticide effects by measuring only lethal effect may underestimate the total negative effect on beneficial arthropods and sublethal effects should be assessed to estimate the total effect of their applications. In this study, sublethal effect of the acaricide abamectin (Vermectin(®) 1.8% EC, Giah, Iran) on the predatory mite Phytoseius plumifer (Canestrini & Fanzago) (Acari: Phytoseiidae) fed on Tetranychus urticae Koch was assessed in laboratory conditions. The adult predators were exposed to the residues of the acaricide on fig leaves and the LC(50) value was determined based on a concentration-response analysis. The results showed that sublethal concentrations (LC(10), LC(20) and LC(30)) of abamectin severely affected the fecundity and longevity of the treated females of P. plumifer. Furthermore, reproductive and life table parameters of the subsequent generation were affected. The results indicated that adverse effects of abamectin on population growth of P. plumifer were significant, so the results from this study can be used to develop approximate guidelines for the use of abamectin in order to minimize their impact on P. plumifer and related natural enemies.