2006 Annual Report 4d.Progress report. This report documents research conducted under a specific cooperative agreement between ARS and the University of California, Riverside. Additional details of research can be found in the report for parent CRIS 5344-22620-017-00D, Ecologically-Based Pest Management Strategies for Western Cotton. Biology, ecology, sampling and control of whiteflies, pink hibiscus mealybug, glassy-winged sharpshooter This project is carried out under a specific cooperative agreement between ARS and the University of California, Riverside. Research focuses principally on chemical control measures directed against major agricultural pests, in particular exotic and invasive pests that have erupted to outbreak proportions. Some of the negative consequences associated with chemical control include insecticide resistance development and non-target impact on natural enemies of the pest species. Resistance monitoring was carried out on field populations of sweetpotato whitefly from Arizona and California and on two exotic strains imported and held in quarantine in California. Laboratory bioassays were carried out with four neonicotinoid insecticides on these various strains to evaluate resistance and cross-resistance patterns. An imidacloprid-resistant strain (IM-R) with 120-fold resistance originally collected from Imperial Valley, California, did not show cross-resistance to acetamiprid, dinotefuran or thiamethoxam. The Guatemala-resistant strain (GU-R) that was also highly resistant to imidacloprid (RR= 109-fold) showed low levels of crossresistance when bioassayed with acetamiprid and thiamethoxam. However, dinotefuran was more toxic than either imidacloprid or thiamethoxam to both IM-R and GU-R strains as indicated by low LC50s. By contrast, a Q-biotype Spanish-resistant strain (SQ-R) that is highly resistant to imidacloprid demonstrated high cross-resistance to the two related neonicotinoids. Field populations from Imperial Valley (California), Maricopa and Yuma (Arizona), showed variable susceptibility to imidacloprid (LC50s ranging from 3.39 to 115 mgmlx1) but did not exhibit cross-resistance to the three neonicotinoids suggesting that all three compounds would be effective in managing whiteflies. In contrast to the sweetpotato whitefly, the glassy-winged sharpshooter proved to be highly susceptible to all insecticides tested against it. The prognosis for continuing effective management against GWSS is good as a combination of chemical and biological control provides stable and balanced control. This same combination of chemical and biological control has also proven effective against the pink hibiscus mealybug (PHM) that currently infests portions of Imperial County, CA. There have been no new infestations of PHM outside of its range in Imperial County that was originally determined in 1999. Imported exotic parasitoids have been released and now mostly control PHM to low levels that help to prevent further spread. Neonicotinoid insecticides have also been shown to be highly effective against PHM and have helped to reduce populations in some areas that were not adequately protected using biocontrol alone.