Insecticidal activity of surfactants and oils against silverleaf whitefly (Bemisia argentifolii) nymphs (Homoptera : Aleyrodidae) on collards and tomato

The insecticidal activities of four surfactants (Cide-kick, Silwet L-77, M- Pede and APSA-80), a dishwashing detergent (New Day), a mineral oil (Sunspr ay oil), a cotton seed oil and a vegetable oil, alone or in combination, we re tested against nymphs of Bemisia argentifolii Bellows & Perring on colla rds and tomato. Silwet L-77 was more effective (>95% mortality) than Cide-K ick or APSA-80 at rates from 0.25-1.00g Al litre(-1) but caused severe phyt otoxicity to tender tomato leaves at all but the lowest rate. New Day dish detergent at 2.0 ml litre(-1) caused mortality (95%) comparable to M-Pede i nsecticide soap at 10-fold greater concentration. A New Day ingredient, coc amide DEA, was considerably more active than the other ingredients or the c ommercial mixture. Additional surfactants added to Sunspray oil increased e fficacy in some treatments, but not others. Toxic responses of 2nd-and 3rd- instar whiteflies to vegetable oil and cotton seed oil at 5.0 and 10.0ml l itre-l plus 0.4g Al litre(-1) APSA-80 ranged from 22.1 to 79.9% and 66.3-88 .7% mortality, respectively. Whitefly mortality was greater on tomato than on collard in six of seven instances when differences between host plants w ere significant. Our results indicate that the these surfactants and oils h ave good potential for controlling B argentifolii. (C) 2000 Society of Chem ical Industry.