|LIU, T.-X - Texas Agrilife Extension|
Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/2011
Publication Date: 10/1/2011
Citation: Liu, T., Greenberg, S.M. 2011. Effects of selected defoliants in combination with insecticides on sweetpotato whitefly (Hemiptera: Aleyrodidae) and its parasitoids in cotton. Journal of Entomological Science. 46(4):308-314.
Interpretive Summary: Frequent insecticide applications on cotton are expensive and create a risk to the environment. We found that pre-harvest application of insecticides at half rates with conventional cotton defoliants performed as well or better than full rates of insecticides alone. Use of this strategy may reduce dispersal of whiteflies to winter crop, increase the effectiveness of whitefly parasitoids, and reduce associated environmental problems.
Technical Abstract: Effects of two defoliants, Def (S, S, Stributylphosphorotrithioate) and Dropp (thidiazuron) alone and in combination with two commonly used insecticides, a pyrethroid, Karate (lambda-cyhalothrin) and an organophosphate, Guthion (azinphosmethyl) on sweetpotato whitefly, Bemisia tabaci Gennadius Biotype B (=silverleaf whitefly, Bemisia argentifolii Bellows & Perring) and its parasitoids were determined in the Lower Rio Grande Valley of Texas. The defoliants, Def and Dropp, and their combinations with Guthion and Karate, significantly affected the infection and survival of sweetpotato whiteflies and their parasitoids, Encarsia spp. and Eretmocerus spp, although the effects varied greatly among the treatments. Karate had no significant effects on sweetpotato whitefly and its parasitoids. We concluded that combining defoliants and insecticides increased the effectiveness on whiteflies and parasitoids on cotton.