Effects of amitraz, buprofezin and propargite on some fitness parameters of the parasitoid Encarsia formosa (Hym.: Aphelinidae), using life table and IOBC methods

The side-effects of amitraz, buprofezin and propargite were studied on Encarsia formosa (Gahan) in the laboratory, using a life table response experiment and the IOBC system for their toxicity. Bioassays were conducted by dipping bean leaves containing third instar nymphs of the whitefly Trialeurodes vaporariorum (Westwood), parasitized by E. formosa, in insecticide solutions or caging adult parasitoids in treated petri dishes. The insecticide buprofezin caused 19.87% and 11.87% mortality in adults and pupae respectively. Amitraz showed the highest level of toxicity for the adults (100% mortality) and the pupae of parasitoids (83.3% mortality). Both buprofezin and propargite caused no adverse effect on the fecundity and longevity of parasitoids, but amitraz significantly reduced the fecundity and longevity of adults. Life table assay indicated that buprofezin and propargite have no major impact on the intrinsic rate of natural increase (rm), while amitraz lowered the rm value by 7.03%. According to the IOBC classification of toxicity, buprofezin was found to be harmless for the pupae and adults and amitraz proved to be harmful for adults. Based on both the life table and IOBC methodology, buprofezin and propargite are found to be relatively safe for E. formosa and can be used in integrated pest management programs where this parasitoid is involved.