Effect of formulated insecticides on Homalodisca vitripennis (Germar) (Hemiptera : Cicadellidae) and its parasitoid Gonatocerus ashmeadi Girault (Hymenoptera : Mymaridae)

• Author(s): Elzen, G; Lauziere, I;
• Abstract: Eleven insecticides were tested using a bioassay of foliar insecticide residue to evaluate their impact on Homalodisca vitripennis nymphs and adults and on Gonatocerus ashmeadi parasitoid pupae and newly-emerged adults. Most compounds caused 100% mortality of H. vitripennis nymphs and adults within the first 24 h following exposure. Dimethoate was significantly less toxic to the nymphs than the other compounds. The insect growth regulators buprofezin and pyriproxifen caused high mortality levels at the end of the 72-h period of observation. They were efficacious against both the H. vitripennis nymphs and adults. Thiamethoxam, acetamiprid, cyfluthrin, fenpropathrin and endosulfan severely affected the immatures and newly-emerged adults of the parasitoid G. ashmeadi with total percent mortality exceeding 65%. Piriproxifen, methomyl, imidadoprid and carbaryl were moderately toxic to the parasitoid pupae and young adults (34-55% total mortality); whereas treatments using buprofezin or dimethoate allowed > 89% survival of the parasitoids. These results may help predict the reliability of these compounds in the field and risks to natural enemies associated with their use. It is possible, however, to choose insecticides that are more selective in toxicity to the glassy-winged sharp-shooter than to its natural enemies.
• Publication Date: Jan 2007
• Journal: Journal Of Entomological Science