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Title: DAILY FORAGING INCIDENCE OF ENCARSIA PERGANDIELLA (HOMOPTERA:APHELINIDAE) ON COWPEA

Author
item Simmons, Alvin
item MCCUTCHEON, GLORIA - CLEMSON UNIVERSITY

Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/7/2000
Publication Date: 4/1/2001
Citation: Simmons, A.M., Mccutcheon, G.S. 2001. Daily foraging incidence of encarsia pergandiella (homoptera:aphelinidae) on cowpea. Journal of Entomological Science. 36:218-221.

Interpretive Summary: Knowledge of how insect parasites behave on plants can help in developing ways to control plant feeding insect pests. We examined how Encarsia pergandiella, a whitefly parasite, was attracted to different crops. Greenhouse tests were conducted on 7 dissimilar crops: cantaloupe, collard, cotton, cowpea, bell pepper, soybean, and tomato, on which whiteflies feed. Although the parasite lays eggs in whitefly nymphs, the tests were conducted on plants free of whitefly nymphs. We also examined daily host searching behavior of the parasite. The parasite was most attracted to cowpea and cotton, and least attracted to collard. The behavior of the parasite on the bottom leaf surface as compared with the top surface varied among crop plants. From 45-90% of the parasites were on the bottom leaf surface during the test. About half were on the top leaf surface early in the morning. By the middle of the day, about 90% of the parasites were on the bottom leaf surface. Overall, parasite searching activity was lowest in the early morning and late afternoon. These findings will be helpful in research on host plant resistance and conservation of parasites.

Technical Abstract: Knowledge of parasitoid relationships with plants may help in the development of management strategies for Bemisia argentifolii Bellows and Perring, a whitefly pest. We examined the influence of various horticultural and agronomic plant species on attractiveness for foraging by Encarsia pergandiella Howard, a whitefly parasitoid. Greenhouse tests were conducted on 7 diverse crops: collard, Brassica oleracea ssp. acephala de Condolle; cotton, Gossypium hirsutum L.; cowpea, Vigna unguiculata (L.) Walpers ssp. unguiculata; melon, Cucumis melo L.; bell pepper, Capsicum annuum L. ssp. annuum; soybean, Glycine max Merrill (L.); and tomato, Lycopersicon esculentum Miller. Although the parasitoid oviposits in whitefly nymphs, the tests were conducted on plants free of whitefly nymphs. We also examined general foraging behavior of E. pergandiella. The parasitoid was most attracted to cowpea, followed by cotton, while the fewest parasitoids were observed on collard. The propensity of the parasitoid to forage on the bottom leaf surface compared with the top surface varied among crops (45-90% were on the bottom leaf surface) and over time (ca. 50% were on the bottom leaf surface around sunrise while ca. 90% were on the bottom surface by mid-day). Overall foraging was low around sunrise, peaked near solar noon, and was low again near sunset.