Preference of the silverleaf whitefly, Bemisia tabaci B biotype, on zucchini squash and buckwheat and the effect of Delphastus catalinae on whitefly populations

Zucchini squash, Cucurbita pepo L., is a high value vegetable crop in Florida. Plant physiological disorders and insect-transmitted diseases associated with the feeding of immature silverleaf whiteflies, Bemisia tabaci B biotype, are serious problems for many growers around the state. The implementation of mixed cropping systems and crops interplanted with alternative host cover crops, when used in conjunction with other pest suppression methods, has the potential to reduce whitefly numbers as well as the impact of whitefly-transmitted viruses on cucurbits. This study investigated the preference of the silverleaf whitefly when given a choice between zucchini squash and buckwheat, and how the introduction of a predator, Delphastus catalinae, would affect whitefly populations. The study was conducted in an open-sided greenhouse with three field cages. The experiment was a randomized complete block design with four replications. Three treatments were evaluated 1) a cage that contained whiteflies, zucchini squash and buckwheat, 2) a cage containing whiteflies, zucchini squash, buckwheat, and D. catalinae, and 3) zucchini squash and buckwheat only (control). Significantly more whiteflies were recorded on zucchini squash compared with buckwheat. We also observed fewer whiteflies in the cage with D. catalinae compared with other treatments. Our findings suggest that combination treatments involving an alternative host and a key predator, D. catalinae, can effectively suppress key pests including B. tabaci without using conventional pesticides. Future studies should consider the effect of intercropping buckwheat with zucchini squash on populations of silverleaf whiteflies and D. catalinae.