Insecticidal Mixture Interactions Against B-strain Sweetpotato Whitefly (Homoptera: Aleyrodidae)

During 1992–1993, nine insecticides and eight mixtures of these insecticides at a 1:1 ratio were tested for their toxicity to adults of the B-strain whitefly, Bemisia tabaci (Gennadius), collected from cotton plants in a greenhouse in the Lower Rio Grande Valley of Texas. Synergistic, additive, or antagonistic properties of the mixtures were determined in a glass vial bio-assay. Endosulfan+bifenthrin was the most toxic mixture tested and was synergistic with a median lethal concentration (LC50) that was significantly less than the LC50s of either insecticide tested alone. Acephate+bifenthrin and amitraz+bifenthrin provided additive toxicity while amitraz+buprofezin and endosulfan+methyl parathion were antagonistic in their effect on adult whiteflies.