Potentiation/Antagonism of Pyrethroids with Organophosphate Insecticides in Bemisia tabaci (Homoptera: Aleyrodidae)

The binary mixtures of pyrethroids cypermethrin, alpha-cypermethrin, zeta-cypermethrin, bifenthrin, fenpropathrin, lambda-cyhalothrin, and deltamethrin plus organophosphates ethion, profenofos, chlorpyrifos, quinalphos, acephate, methamidophos, methyl parathion, and triazophos were evaluated on putatively resistant field populations of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) from Pakistan using a leaf-dip bioassay. Ethion exhibited good potentiation with all the pyrethroids. Quinalphos potentiated cypermethrin, fenpropathrin, and lambda-cyhalothrin but not bifenthrin. Acephate was potentiating with bifenthrin and fenpropathrin but antagonistic with zeta-cypermethrin. A potentiation effect was also found when methamidophos was mixed with bifenthrin and fenpropathrin. However, profenofos was antagonistic with cypermethrin, bifenthrin, and lambda-cyhalothrin. Similarly, bifenthrin + methyl parathion and deltamethrin + triazophos mixtures were antagonistic when tested on several populations of B. tabaci. Chlorpyrifos was antagonistic with cypermethrin but had an additive effect with fenpropathrin.