Insecticide resistance in field populations of greenhouse whitefly (Homoptera: Aleyrodidae) in the San Joaquin Valley (California) cotton cropping system

Omer, A.D.; Leigh, T.F.; Granett, J.

Insecticide resistance in field populations of greenhouse whitefly (Homoptera: Aleyrodidae) in the San Joaquin Valley (California) cotton cropping system

1992

Omer, A.D. | Leigh, T.F. | Granett, J.

Susceptibility of field populations of greenhouse whitefly, Trialeurodes vaporariorum Westwood, in the San Joaquin Valley (California) cotton cropping system was tested with laboratory bioassays with acephate and dicrotophos. Approximately 9.5-fold resistance to acephate and 18.5-fold resistance to dicrotophos were detected. Results of bioassays indicated that 56.2 ppm acephate and 316 ppm dicrotophos could serve as discriminating concentrations for detecting resistant T. vaporariorum populations. Field trials demonstrated lack of control with acephate and dicrotophos in resistant T. vaporariorum. Susceptibility levels to acephate and dicrotophos of 32 T. vaporariorum field populations collected from cotton and other hosts including weeds in Kern, Kings, and Tulare counties were estimated by bioassays with discriminating concentrations. Substantial regional variability in susceptibilities to the two pesticides was found. Resistant and susceptible T. vaporariorum phenotypes occurred on cotton and other cultivated or weed hosts. Cross-resistance between acephate and dicrotophos is suggested. Implications of these results for integrated pest management of cotton system in the San Joaquin Valley are discussed.

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