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

Authors

Abstract

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.

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