CHARACTERIZATION OF NEONICOTINOIDS AND THEIR PLANT METABOLITES IN CITRUS TREES AND GRAPEVINES, AND EVALUATION OF THEIR EFFICACY AGAINST THE GLASSY-WINGED SHARPSHOOTER AND THE EGG PARASITOID GONATOCERUS ASHMEADI

• Author(s): Byrne, Frank; Toscano, Nick;
• Abstract: The neonicotinoids are highly effective insecticides for the management of glassy-winged sharpshooters GWSS). The systemic activity of the insecticides exploits the feeding behavior of the sharpshooter at all life stages. Imidacloprid was also toxic to the egg stages. This toxicity was manifested at the time of emergence of the 1(st) instar from the egg mass, and not during the development of the embryo. Imidacloprid metabolites were found to be effective against adult and egg stages of the sharpshooter. In accordance with data from studies on aphids and whiteflies, the olefin and 5-hydroxy metabolites were most toxic, while the desnitro and diol derivatives lacked any toxic effect. Metabolites were detected in the xylem fluid extracted from citrus trees that had been treated with Admire. The source of these metabolites is not yet clear they may originate from imidacloprid metabolism within the soil before uptake by the trees, or they may have been formed within the trees themselves. Nevertheless, our results confirm that sharpshooters feeding on citrus will encounter imidacloprid metabolites that will contribute to its toxicity. We are currently evaluating the metabolic fate of the other neonicotinoids.
• Publication Date: Dec 2005
• Journal: 2005 Pierce's Disease Research Symposium