Susceptibility of Aphidius nigripes (Hym.: Aphididae) adults to entomopathogen Lecanicillium muscarium (Deut.: Moniliales)

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Abstract

Susceptibility of Aphidius nigripes Ashmead adults to entomopathogen Lecanicillium muscarium (Petch) Zare & Gams was evaluated with different inoculation methods. Fungus concentrations including 104, 105, 106, 107, 108 spores/ml and control (distilled water with 0/04% triton x-100) were applied by spraying or dipping method on males, females and pupa of parasitoid and mortality was counted daily during 8 days. Both A. nigripes males and females were infected by L. muscarium concentrations. Minimum mortality was observed in 104 spores/ml treatment on the males and females after 8 days. Positive correlation was observed between concentrations and parasitoid mortality. Direct infection method with 108 spores/ml showed the maximum mortality of 97/9% and 100% for females and males, respectively. Estimated LC50 for females was approximately three times more than that of males. LT50 for each concentration indicated more susceptibility of males than the females. Adult wasps were also infected by fungus spores of inoculated plants; however, the mortality of parasitoid was less than that of direct infection (sprayed on adults). Estimated LC50 and LT50 were also greater than those obtained by direct infection of adults. Mummified aphids were infected by L. muscarium, however, the development of fungus mycelium was observed on mummies, and the mortality of parasitoid pupae within mummies was significantly low. A few parasitoids emerged from infected mummies suffered mortality. Further results demonstrated that the adult infection had come in touch with the infected mummies.

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Journal of Entomological Society of Iran
Volume 28, Issue 1
September 2008
Pages 1-18

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