Comparative Tolerance of Native and Exotic Parasitoids of the Sweetpotato Whitefly to Cotton Insecticides

Walker A. Jones, D. F. Wolfenbarger, A. A. Kirk


The effectiveness of parasitoids of the sweetpotato whitefly Bemisia tabaci (Gennadius) in a multi-crop and multi-pest system will require the use of insecticide tolerant parasitoids or materials with low residual activity or high selectivity because other pests still require insecticide for their control. Tests were conducted to determine the susceptibility of four parasitoids of B. tabaci to seven cotton insecticides. The parasitoids were the native species Eretmocerus sp. nr. californicus Howard and Encarsia pergandiella Howard; the exotic species were Eretmocerus mundus Mercet and Encarsia formosa Gahan. Insecticides, applied as sprays to potted cotton plants at recommended rates, were amitraz (Ovasyn®), azinphosmethyl (Guthion®), bifenthrin (Capture®), buprofezin (Applaud®), cypermethrin (Ammo®), methyl parathion and thiodicarb (Larvin®), with a water control. Significant differences in toxicity were detected among the insecticides. Buprofezin was not toxic to any of the four parasitoids. When parasitoids were exposed to leaves sprayed two days previously, only amitraz, among the remaining insecticides, allowed significant levels of survival after two days. E. mundus demonstrated the greatest tolerance to insecticides, with 40% or more surviving 48 hr exposure to leaves sprayed with amitraz, thiodicarb and cypermethrin, although survival was much reduced after 96 hr exposure.

Reprinted from Proceedings of the 1994 Beltwide Cotton Conferences pp. 1234 - 1236
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998