2008 Annual Report 1a.Objectives (from AD-416) Establish baseline responses to insecticides where feasible and evaluate longer term performance to safeguard against resistance development. Incorporate resistance management strategies into pest management programs for particular pests of cotton and associated crops including silverleaf whitefly, glassy-winged sharpshooter, and Lygus spp. 1b.Approach (from AD-416) Develop bioassay methods for various insect pests that realistically depict the type of exposures that occur in the field. Collect target pests in their crop habitat and establish and maintain cultures for repetitive testing. Evaluate relative susceptibilities to crucial insecticides by examining dose-mortality responses of immature and adults stages. Determine stability of resistance when it occurs in populations and formulate effective strategies for mitigating resistance by incorporating information on resistance stability. Documenst SCA with UC Riverside. 3.Progress Report The principal concern over glassy-winged sharpshooter (GWSS) in California is its role as a vector of the bacterial pathogen Xylella fastidiosa. Large populations that had continued to expand in California through 1999 proved relatively easy to control by area-wide applications of insecticides that began in 2000. Pockets of modest to high populations still remain in some regions of California including the Riverside area and the farm at UC Riverside. Attention has turned from which materials control GWSS to the potential role that citrus plays as a host of both the vector and the pathogen. A former project monitoring incidence of X. fastidiosa in GWSS populations indicated that GWSS individuals that fed exclusively on citrus tested positive for X. fastidiosa. To further evaluate citrus as a potential host of X. fastidiosa, xylem fluid samples have been collected in 2008 from navel and Valencia oranges, mandarins, lemons, and rough lemon groves at UC Riverside. ELISA tests performed thus far show a relatively low percentage that test positive for X. fastidiosa. This low percentage is expected to increase once PCR tests have been optimized that will enable much greater sensitivity of detection. In the meantime, extensive ELISA results already support the concept as a host of X. fastidiosa, and given its importance as a host of GWSS, the potential importance of citrus in the epidemiology of X. fastidiosa increases dramatically. ADODR monitors activities by phone calls and site visits.