Submitted to: Subtropical Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/2013
Publication Date: 12/31/2012
Citation: Legaspi, J.C., Simmons, A.M. 2012. Evaluation of selected commercial oils as oviposition deterrents against the silverleaf whitefly, Bemisia argentifolii (Hemiptera:Aleyrodidae). Subtropical Plant Science. 64:49-53.
Interpretive Summary: Despite significant research efforts since the 1990s, the silverleaf whitefly remains a serious worldwide pest of vegetables and ornamentals because it attacks many host plants, has high mobility and reproduction, and is resistant to insecticides. However, relatively little research has addressed the possibility of using repellent plants or plant products to make the crop unattractive to the pest, i.e. “pushing” the pest away. When combined with the complementary tactic of attracting the pests to a trap crop (“pull” strategy), “push-pull” pest management is a promising sustainable alternative to conventional pest control, especially for small farmers. As part of a program to develop a “push-pull” management strategy against the whitefly, scientists with the USDA/Agriculture Research Service, Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, Florida, studied the effects of commercial repellent oils in a two-part experiment. In the first experiment we sprayed squash plants with hot pepper wax, garlic oil, mustard oil and horticultural petroleum oil. The highest numbers of eggs were found in the water control and hot pepper wax treatments. In the second experiment, whiteflies were allowed to choose between plants sprayed with a repellent product and an untreated control plant (a “choice” study). In conclusion, we found some reduction in the numbers of eggs laid by whiteflies due to repellent oil treatments, although the reduction is modest and will likely require complementary controls for effective whitefly management. The mustard oil treatment is most promising as the “push” component in a “push-pull” management program.
Technical Abstract: Silverleaf whitefly (SLWF), Bemisia argentifolii Bellows and Perring, remains a serious economic pest of vegetables and ornamentals worldwide. Conventional chemical control of whiteflies is often rendered ineffective due to rapid development of insecticide resistance. However, relatively little research effort has been reported on cultural management techniques, such as habitat manipulations that could mitigate economic loss due to whitefly damage. The use of extracts and oils of certain other plants as repellents or oviposition deterrent may be an important cultural management technique. We evaluated four commercial oils as repellents or oviposition deterrents against the silverleaf whitefly (“push” factor) as a component of the “push-pull” management strategy. Potted squash plants (Cucumis moschata Duchesne ex Poir) were sprayed with the following four oil treatments at recommended label rates: garlic oil (11%), hot pepper wax oil (3%), mustard oil (3%) and horticultural petroleum oil (1%). TWEEN 20® (2%) was used as a spreader in all the solutions. Water + TWEEN 20® solution served as the control. SLWF adults were released in no-choice and choice experiments for 24 hrs. In the no-choice experiment, we found significantly higher numbers of SLWF eggs in the control and hot pepper wax oil treatments compared to those sprayed with treatments of garlic oil, mustard oil and horticultural petroleum oil. In the choice experiment, mustard oil significantly reduced both numbers of SLWF adults and newly-laid eggs. The results for the horticultural petroleum oil treatment were not as clear. Although SLWF adult counts were significantly reduced, egg counts were significantly reduced only at the 10 % level (P = 0.054). These results indicate that the mustard oil treatment is most promising as the “push” component in a “push-pull” management program. This study will be useful in enhancing integrated pest management strategies against the silverleaf whitefly pest in vegetable and horticultural crops.