Toxicity and Pharmacokinetics of Insect Growth Regulators and Other Novel Insecticides on Pupae of Hyposoter didymator (Hymenoptera: Ichneumonidae), a parasitoid of early Larval Instars of lepidopteran Pests

SCHNEIDER, M., G. SMAGGHE, A. GOBBI AND E. VIÑUELA

JOURNAL OF ECONOMIC ENTOMOLOGY

Entomological Society of America (ESA) , CAB

Lugar: USA; Año: 2003 vol. 96 p. 1054 - 1065

0022-0493

ABSTRACT Susceptibility of the lepidopteran parasitoid Hyposoter didymator (Thunberg) to seven modern insecticides, azadirachtin, dißubenzuron, halofenozide, methoxyfenozide, pyriproxyfen, tebufenozide, and spinosad, was tested in the laboratory. Pupae were exposed to different doses of each compound by direct topical application. At the Þeld recommended doses, methoxyfenozide and tebufenozide had no effect on H. didymator. Halofenozide had a low effect on both adult emergence and adult survival but the progeny size and parasitism capacity were not affected. Dißubenzuron was moderately toxic to the parasitoid, while azadirachtin, pyriproxyfen and spinosad were very toxic, affecting all its life parameters. In the pyriproxyfen and spinosad treatments, no progeny was obtained. As a second approach of this study, we determined the rate of penetration through the pupal cocoon and absorption in the parasitoid body as pharmacokinetic parameters important for toxicity. Most of the radioactivity was retained in the silken cocoon, indicating a low accumulation in the parasitoid body. Among all compounds tested, dißubenzuron exhibited the highest absorption in the parasitoid body, followed by pyriproxyfen. For halofenozide, methoxyfenozide and tebufenozide, low absorption (2%) was found. In addition, we tested for the presence of molting hormone receptors in Hyposoter tissues using a monoclonal antibody 9B9. Our data suggest that the use of dißubenzuron, azadirachtin, pyriproxyfen, halofenozide, and spinosad in combination with H. didymator in integrated pest management (IPM) programs should be carefully evaluated. Methoxyfenozide and tebufenozide could be considered safe for this parasitoid.