Effects of Pyriproxyfen on Three Species of Encarsia (Hymenoptera: Aphelinidae), Endoparasitoids of Bemisia argentifolii (Homoptera: Aleyrodidae)

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Abstract:

Effects of the phenoxy juvenile hormone analog pyriproxyfen were evaluated in the laboratory on larvae, pupae, and adults of the endoparasitoids Enearsia pergandiella Howard, E. transvena (Timberlake), and E. Formosa Gahan, as well as on their host, Bemisia argentifolii Bellows & Perring. Although B. argentifolii nymphs reared on sweet potato leaves and treated as 1st, 2nd, or 3rd instars with pyriproxyfen developed to the pupal stage, <5% adult emergence was observed. However, when treated in the 4th instar, adult emergence was ≥70%, and when treated as pupae, ≥97%. Of the 3 parasitoids tested, pyriproxyfen was least harmful to E. pergandiella and most deleterious to E. formosa. Concentrations of 1.00, 0.05, and 0.01 mg (AI)/liter applied to whitefly nymphs 6.5 d after parasitization caused significant reduction in subsequent adult emergence of E. Formosa at the greatest rate, but not of E. pergandiella. Effects of treatment of whitefly nymphs containing E. Formosa pupae (11.4 d after parasitization) were even more striking—73.5 and 44.6% reduction in emergence at the 2 highest rates, with wing deformations observed in a large proportion of emerging adults. Development time of all 3 Encarsia species was increased signincantly by exposure to pyriproxyfen shortly after oviposition, and parasitization of B. argentifolii by E. Formosa adults treated as larvae was reduced 21.4—56.8% compared \with untreated parasitoids. However, residues of 2 higher rates reduced the progeny by 30.7—42.3% and rate of emergence by 11.2— 27.6% with E. Formosa, and to a lesser extent the progeny by 21.7—29.3% and adult emergence by 3.2-11.0% of E. transvena. Thus, pyriproxyfen proved to be effective against B. argentifolii, safe to E. pergandiella, and relatively safe to E. transvena, but relatively toxic to E. Formosa, especially pupae.

Document Type: Research Article

Publication date: April 1, 1997

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  • Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.
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