The silverleaf whitefly, Bemisia argentifolii, is a major plant pest throughout the tropical and temperate regions of the world. Sugar beets are one of the few plants not affected. Greenhouse whiteflies, Trialeurodes vaporariorum, also are frequent pests throughout the world and in greenhouses. Of the many other species of whiteflies (approximately 1200), some are localized pests on specific plants. In the early 1990s, an epidemic of silverleaf whiteflies was estimated to cause losses of over $200,000,000 annually in Arizona, California, Florida and Texas.
Whiteflies feed on the phloem sap of plants and excrete sticky, sweet honeydew which contaminates plant leaves and fruit, gums up cotton gins, and promotes bacterial and mold growth.
In cooperation with ARS, Phoenix, AZ, and with Dr. Thomas P. Freeman at North Dakota State University, we are studying the surface waxes produced in copious amounts by these insects, the processes by which they penetrate the leaf and reach the phloem bundles, the attachment of their eggs to the surface of the leaf, and whether leaf morphological features influence the selection of oviposition and feeding sites.
Parasitoids of whiteflies are being characterized by identifying the hydrocarbon components of their cuticular lipids and their effect on the cuticular chemistry of parasitized nymphs. In collaboration with Dr. Arland E. Oleson, Professor of Biochemistry, North Dakota State University, and Dr. Jianzhong Zhang, DNA probes are being developed that allow the identification of the species of parasite infesting a whitefly nymph.