Effects of predatory mite Ambylseius swirskii and acylsugar tomato lines on whitefly suppression

Plant defense traits such as trichomes along with biological control agents may provide alternatives to insecticide use in tomatoes. However, the plant-herbivore-natural enemy trophic interaction is not always complementary. In this study, we aim to explore the role of tomato plants with augmented defense traits and their compatibility with an effective whitefly biological control agent, Ambylseius swirskii, in managing whitefly populations. We conducted a factorial organic field experiment followed up by a greenhouse experiment where we combined A. swirskii treatments with acylsugar producing tomato varieties and commercial varieties to assess their combined performance in whitefly management. For the field experiment, predatory mites were applied to the plants in three different ways: dusting on top, bottom, mite sachet and no mite control. Only mite sachets were used in the greenhouse experiment. Leaflet samples were taken weekly to count predatory mites and whiteflies. Although we observed high quality mite numbers prior to introducing on the tomato plants, few mites were recovered from either the field or greenhouse. Acylsugar lines were more effective in suppressing whitefly populations as compared to commercial lines, but Tomato Yellow Leaf Curl Virus was detected at higher frequencies in acylsugar lines compared to commercial lines. Combined our results suggest A. swirskii does not establish well on tomatoes, and acylsugar lines successfully decrease whitefly populations but not disease.