Effects of oil and oil-surfactant combinations on silverleaf whitefly nymphs (Homoptera: Aleyroididae) on collards

Collards, Brassica oleracea L., treated with SunSpray Ultra-Fine(R) oil with and without silicon-based oil surfactants were evaluated for effects on nymphs of Bemisia argentifolii Bellows & Perring. Synchronously developing populations of eggs, small nymphs and pupae on collards were sprayed to run-off. The rate of egg hatch was not affected by oil treatments. Treated nymphs, pupae, and crawlers emerging from treated eggs, were affected by all oil treatments. Of those nymphs that were affected by the oil, approximately 50% to 75% were killed outright. Over 90% of those that remained alive developed abnormally, remaining small and failing to molt into the next stage. Adults failed to emerge from approximately 94% to 99% of treated pupae. Oil surfactants did not significantly alter whitefly mortality when used with paraffinic oil.