Control of tomato whiteflies using the confusion effect of plant odours

Glasshouse tomato production is reduced by the whitefly Trialeurodes vaporariorum, a major worldwide pest of glasshouse crops. Whitefly control is achieved using pesticides or parasitoids, which have drawbacks. There is thus a need for other control methods. For instance, the use of volatile compounds from plant odours could profoundly change the behaviour of plant-eating insects. This practice should be safe because plant odours are usually harmless to humans. Therefore, we have studied the effect of plant volatiles on whiteflies feeding on tomato plants. The rationale was to use the confusion effect by supplying whiteflies with a super-abundance of volatiles. We removed plant headspace volatiles from multiple whitefly host plants. Then, we presented these volatiles to whiteflies feeding on tomato plants. At the same time, whitefly stylet penetration is monitored using electrical penetration graphs (EPG). Plant colonisation, egg laying and honeydew production are analysed in separate experiments. Data are compared to controls in which extracted volatiles from tomato and air alone are presented to the whiteflies. The only significant effect produced by exposure to multiple-host volatiles is a pronounced reduction in the incidence of phloem-related waveforms during the 15-h EPG recording. This represents a delay in, rather than a cessation of, phloem-related activities as there is no related reduction in long-term performance. The confusion effect thus does not appear to exert strong effects on whitefly behaviour here.