Modifying the expression of plant volatiles to affect the behaviour of greenhouse insect pests

Abstract: Plant volatile organic compounds (VOCs) are known to attract insect herbivores and pollinators, as well as the predators and parasitoids of plant pests. Our recent findings have demonstrated how the feeding and oviposition habits of insect pests are affected by VOCs produced by the over-expression of genes in Arabidopsis thaliana and tomato Solanum lycopersicum. The overall project objectives were to determine whether the transgenic plants producing attractive or repellent volatiles can: 1) be applied as a trap crop for greenhouse whiteflies Trialeurodes vaporariorum (Westwood) and cabbage loopers Trichoplusia ni Hübner, and 2) be used as components in a “push-pull” strategy. In the present research the focus was on the attractive volatiles produced by transgenic tomatoes. The orientation of cabbage looper moths was toward transgenic relative to wild-type tomato plants (62% vs. 38%, respectively) in Y-tube olfactometer assays. Similarly, there was greater preference for transgenic tomato by the cabbage looper and whitefly as a site for oviposition (OPI values -0.36 and -0.63, respectively). Chromatographic analyses measured increased levels of specific monoterpenes and decreased levels of sesquiterpenes from the transgenic tomato believed to be responsible for the observed insect behaviour. The long term goal of this research is to allow us to manipulate natural plant volatiles as an environmentally sustainable pest control strategy that is compatible with other bio-based pest management tools such as parasitoids, predators and microbial control agents.