BEMESIA ARGENTIFOLII (HOMOPTERA, ALEYRODIDAE) - HOST PREFERENCE AND FACTORS AFFECTING OVIPOSITION AND FEEDING SITE PREFERENCE

Bemisia argentifolii Bellows Er Perring preferred cantaloupe, Cucumis melo, var. cantalupensis L., to cotton, Gossypium, hirsutum L., broccoli, Brassica oleracea var. botrytis L., and lettuce, Lactuca sativa var. capitata L., in 1992 and 1993 in field and greenhouse studies. In the absence of cantaloupe, B. argentifolii preferred cotton to broccoli and lettuce, respectively. More eggs and fewer nymphs were found on broccoli than on cotton in the field. Differences in relative abundance of vascular bundles per unit of leaf area among the four plant species may partly account for differences in oviposition site selection. Vascular bundle volume per unit of leaf tissue volume was 50% greater in cantaloupe than in cotton and broccoli, which in rum had significantly greater volumes than lettuce. Field studies showed that most B. argentifolii on cotton and cantaloupe leaves were found on lower leaf surfaces. Distances from upper and lower leaf surfaces to the nearest vascular bundles in cotton leaves were 131 and 60 mu m, respectively. This distribution favors oviposition and feeding on the lower surface of a leaf. Leaf structure, positive effect of gravity, and negative effect of light affected oviposition site preferences in laboratory studies.