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Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/19/2002 Publication Date: 5/21/2002 Citation: SIMMONS, A.M. SETTLING OF CRAWLERS OF BEMISIA TABACI (HOMOPTERA: ALEYRODIDAE) ON SELECTED VEGETABLES. ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA. 2002. v.95(4) p.493-497. Interpretive Summary: The B-strain of the sweetpotato whitefly damages many vegetable crops. The nymphal stage of whitefly pests is important because of its relationship to pest management measures and the spread of plant diseases and other plant disorders. The active first instar of the nymphal stage, which is called a crawler, is the only mobile form of the immature whitefly. A study was conducted to determine any influence of vegetable plant species or temperature on the distance moved by crawlers of the B-biotype sweetpotato whitefly. Tests were conducted in the greenhouse and under laboratory conditions on five vegetable crops(cantaloupe, collard, cowpea, pepper, and tomato). The distance moved from the egg to the site where the crawler stopped traveling was shortest (about 0.1 inches) on collard. The crawler stopped traveling about 0.4-0.6 inches from the site of hatching on the other vegetable crops. Observations on collard indicated that the crawlers traveled 21 minutes while it was a 1st instar. They generally traveled 3 times. On average, each trip was separated by a 2-hour rest. No effect of temperature (61-93 degrees F) was detected on the travel distance of the crawler. The data suggest that among the crop species in this study, collard is highly attractive for feeding and/or it offers suitable feeding sites that are easy to locate by the crawler. Also, because of the little movement, there may be little chance of the crawler moving onto toxic residues when there is incomplete insecticide spray coverage on the collard leaf. The results of this study help define the behavior of crawlers on several host crops and will help in understanding the resistance of plants to whiteflies. Technical Abstract: The B-biotype sweetpotato whitefly, Bemisia tabaci (Gennadius), feeds on and damages numerous vegetable crops. The nymphal stage of whitefly pests is important in terms of its relationship to pest management measures, disease epidemiology and other plant disorders. The active first instar, which is called a crawler, is the only mobile form of the immature whitefly. A study was conducted to determine any influence of vegetable plant species and temperature on net distance moved (between the egg site and final resting site) by crawlers of the B-biotype B. tabaci. Tests were conducted in the greenhouse and under controlled laboratory conditions on five vegetable hosts: cantaloupe, Cucumis melo L.; collard, Brassica oleracea ssp. acephala de Condolle; cowpea, Vigna unguiculata (L.) Walpers ssp. unguiculata; pepper, Capsicum annuum L. ssp. annuum; and tomato, Lycopersicon esculentum Miller. The net distance moved was shortest on collard in which the crawler ceased traveling about 2 mm from where it hatched. The crawler ceased traveling about 10-15 mm from the site of hatching on the other vegetable host plants. Observations on collard in the laboratory indicate that the crawlers traveled 21 minutes before developing to the 2nd instar. No effect of constant temperature (16-34oC) was detecte on the net travel distance of the crawler. The data suggest that among the plant species in this study, collard is highly attractive for feeding and/or it offers suitable feeding sites that are easy to locate by the crawler. The results of this study help define the behavior of crawlers on several host plants. |
