Fourth International Bemisia Workshop International Whitefly Genomics Workshop
Management of Bemisia Resistance: Cotton in the Southwestern USA
1 Department of Entomology, University of Arizona, Tucson, AZ, USA. Correspondence: tdennehy@ag.arizona.edu
2 University of Arizona, Maricopa Agricultural Center, Maricopa, AZ, USA
3 Cotton Incorporated, Cary, NC, USA
Bemisia tabaci can be a severe pest of many crops produced in arid regions of the southwestern United States including cotton, melons and vegetables. It has also become an increasingly common problem in glasshouse production systems. Attempts to control whiteflies with conventional broad-spectrum insecticides have had devastating results in many desert agro-ecosystems. Severely reduced natural enemy populations have been associated with resurgences of whiteflies, outbreaks of secondary pests, and rapid evolution of pest resistance. Under such conditions, B. tabaci has developed resistance to essentially all insecticides to which it has been repeatedly exposed. Such was the case in 1995, when whitefly numbers reached crisis proportions in Arizona cotton despite application of 6 to 15 insecticide treatments per acre. In consultation with researchers in Israel and the United Kingdom, emergency alternatives for whitefly control were formulated and implemented in 1996 that replaced broad-spectrum insecticides during the early season with once-per-season use of the insect growth regulators, pyriproxyfen and buprofezin. Concomitant registration of Bt cotton significantly reduced treatments of conventional insecticides for lepidopteran pests. Additionally, neonicotinoid insecticides provided exceptional whitefly suppression in the other major whitefly hosts, melons and winter vegetables. The end result has been over a decade of unprecedented low insecticide use in cotton, and equally unprecedented effectiveness of biological control in cotton fields. Management of Bemisia resistance in the Southwestern USA is focused intensively on sustaining effective, selective insecticides. This includes statewide detection and isolation of resistance in cotton, vegetables, melons and glasshouses, and collaborative research to characterize critical toxicological, genetic and ecological parameters of resistance in laboratory and field experiments. I will overview new developments from this research, including information regarding the distribution and threat posed by Q biotype.
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