Dynamics of resistance to organophosphate and carbamate insecticides in the cotton whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) from Pakistan.

摘要

Field populations of adult whiteflies, Bemisia tabaci, from Pakistan were monitored from 1992 to 2007 for their susceptibility to seven organophosphate and three carbamate insecticides using a leaf-dip method. Malathion, quinalphos and chlorpyrifos generally exhibited no or a very low level of resistance in B. tabaci over a 16-year monitoring period. Resistance to profenofos, triazophos, parathion-methyl and ethion was usually low to high up to 1995, and then it dropped to very low levels during 1996-2004. Resistance levels again picked up from low to moderate levels for triazophos during 2005-2007, for parathion-methyl during 2003-2007, and for ethion in 2006. Among carbamates, thiodicarb resistance was high during 1994-1996, which dropped to moderate levels in 1997 and 1998 and to very low levels during 1999-2001, but again increased from low to high levels during 2002-2007. Methomyl resistance was moderate in 1994 and 1995, which dropped to very low levels during 1996-2002, and then increased to low levels during 2003-2007. Butocarboxim resistance remained very low during 1994-2003 and then increased from low to high levels during 2004-2007. The insecticides exhibiting no, very low or low resistance, and no cross-resistance among themselves can be exploited in devising an insecticide resistance management strategy to combat whitefly resistance in the field.