OVIPOSITION ON VEGETABLES BY BEMISIA-TABACI (HOMOPTERA, ALEYRODIDAE) - TEMPORAL AND LEAF SURFACE FACTORS

Selection of ovipositional site of the sweetpotato whitefly, Bemisia t abaci (Gennadius), strain B, was studied under field, greenhouse, and laboratory conditions on early vegetative growth of commercial cultiva rs of 10 vegetable crops: cantaloupe (Cucumis melo L.), cucumber (Cucu mis sativus L.), eggplant (Solanum melongena L.), bell pepper (Capsicu m annuum L. ssp. annuum), collard (Brassica oleracea ssp. acephala de Condolle), cowpea (Vigna unguiculata (L.) Walpers ssp. unguiculata), s nap bean (Phaseolus vulgaris L.), summer squash (Cucurbita pepo L. ssp . melopepo), tomato (Lycopersicon esculentum Miller), and watermelon ( Citrullus lanatus (Thunberg) Matsum. & Nakai ssp. lanatus. Feeding and oviposition started on the cotyledon stage and populations of immatur e B. tabaci increased over time on all crops in field and greenhouse t rials. On most plants, from 90 to 95% of the eggs were laid on the low er surface, with no definitive change over time or among leaves of a g iven crop. In a laboratory choice test using detached leaves facing do wnward, the lower leaf surface of cantaloupe, squash, and watermelon, was preferred for oviposition as compared with the upper surface. Howe ver, the upper surface was preferred in cowpea. There was no preferenc e for egg-laying between leaf surfaces on the six other vegetables in the laboratory. Four crops, cantaloupe, cowpea, snap bean, and squash were evaluated for whitefly geotropic response for oviposition, and th ere was a strong negative response.