CHEMICAL CONTROL OF GLASSY-WINGED SHARPSHOOTER: ESTABLISHMENT OF BASELINE TOXICITY AND DEVELOPMENT OF MONITORING TECHNIQUES FOR DETECTION OF EARLY RESISTANCE TO INSECTICIDES

• Author(s): Castle, Steven; Toscano, Nilima;
• Abstract: Among the control practices used against the glassy-winged sharpshooter (GWSS) that spreads Pierces disease, chemical control offers an immediate remedial option against this pest. Insecticides were not used extensively until recently to control this pest and therefore efficacy of insecticides should be evaluated and monitored. Our present challenge is to study the effectiveness of selected insecticides representing various chemistries against the GWSS and to establish baseline toxicity of various insecticides. Knowledge of baseline toxicities would facilitate the selection of the most effective products for use in GWSS management. The results of tests conducted in the laboratory under controlled conditions can provide practical guidance to individual growers without conducting expensive large-scale trials to determine the suitability of an insecticide. Conventional bioassays provide rapid and field-based information to establish baseline toxicity data. In order to establish baseline susceptibility data to various insecticides against the GWSS, evaluation and development of simple and suitable bioassay techniques to detect toxicological responses of the insects to various insecticides is critical. Ideally, bioassay techniques should require less handling of insects and also be sensitive enough to allow early detection of changes in an insects response to insecticides over time. Changes in the toxicological response of a population to an insecticide is usually the first indication of resistance development. Hence, the priority of our project was to evaluate and standardize 3 bioassay techniques at the present time with the possibility of developing 2 more techniques in the future. The purpose of the report is to describe three techniques, a petri-dish and a leaf-dip bioassay technique used for testing the relative susceptibilities of GWSS to a number of contact insecticides, and a systemic-uptake bioassay method for systemic insecticides. The baseline data obtained so far to selected insecticides against the GWSS can be useful for future studies on resistance monitoring and management of this pest. The availability of these three techniques will allow us to also examine various strategies of management with chemicals to avoid or delay insecticide resistance. Testing various chemical application strategies to manage GWSS populations will be critical to understand the evolution of resistance in GWSS.
• Publication Date: Dec 2001
• Journal: 2001 Pierce's Disease Research Symposium