Insecticide resistance and biotype status of populations of the tobacco whitefly Bemisia tabaci (Hemiptera : Aleyrodidae) from Turkey

Analysis using polyacrylamide gel electrophoresis (PAGE) of four strains of the tobacco whitefly, Bemisia tabaci, collected from cotton in Turkey showed all insects to be assignable to the geographically widespread B biotype of this species. Bioassays with appropriate life-stages were used to investigate the status of resistance to two pyrethroid insecticides (bifenthrin and fenpropathrin), two organophosphates (OPs) (formothion and triazophos) and an insect growth regulator (buprofezin). All four strains showed significant resistance to pyrethroids (57- to 360-fold) and OPs (20- to 310-fold). Resistance to buprofezin was found only in a strain from Izmir. Total non-specific esterase activities were 7.4-11-fold greater than in an in secticide-susceptible strain, and were likely to account, in part at least, for resistance to pyrethroids. Inhibition assays with acetylcholinesterase also implicated target-site modification as a mechanism of resistance to OPs. The data update previous results on the resistance status of B. tabaci in Turkey and the implications for managing resistance on cotton and other whitefly hosts are discussed. (C) 2007 Elsevier Ltd. All rights reserved.