Dr. Frank Byrne, University of California-Riverside, $15,000, 2 year project

Other Project Team Members -

Mr. James Bethke, Floriculture Farm Advisor, UCCE San Diego

Executive Summary
Insecticide resistance is one of the major problems associated with the effective control of the whitefly Bemisia tabaci.  The problem is compounded by the existence of several biotypes of this pest, each with the capacity to develop its own unique form of resistance.  Until 2005, growers in the United States had one biotype, the B-biotype (aka Bemisia argentifolii), to contend with, and much progress has been made in developing strategies to deal with its management.  In 2005, a new biotype (the Q-biotype) was detected in the United States for the first time, and a subsequent survey showed that this biotype was highly pervasive (22 states).  Furthermore, it exhibited resistance to insecticides known to be effective against the B-biotype.  With the existence of two Bemisia biotypes, new approaches to improving the management of whitefly outbreaks are being evaluated.  The propensity to deal with whitefly outbreaks will depend on a sound knowledge of the biotype identity, and on the level of resistance expressed within that biotype population.  Biotype identification services are available for growers; however, knowledge of the resistance status of Q-biotype populations that are establishing within the United States is lacking.  This project will determine the resistance status of populations of B- and Q-biotype Bemisia tabaci collected from several states within the U.S.  Resistance and cross-resistance profiles will be determined for each population for the major insecticide groups.  This information will alert the industry to the necessary adjustments required if both biotypes are to be effectively managed.  We will also define levels of tolerance for the main neonicotinoid insecticides administered as either foliar or drench applications.  This will define a level of persistence for the neonicotinoids, which growers can utilize to plan their treatment strategies more effectively.
For further information contact Dr. Frank Byrne at frank.byrne@ucr.edu