Using herbivore induced plant volatiles and environmental factors for sensitive monitoring of pests infestation in greenhouse tomato crops

Suitability of herbivore-induced plant volatiles as indicators of cabbage looper (Trichoplusia ni, Noctuidae) infestation on tomato plants was assessed for developing a pest monitoring system inside tomato greenhouses. From volatile blends of infested tomato plants, four compounds have been selected as T. ni infestation indicators: (Z)-3-hexenyl acetate, (E)- β-ocimene, limonene and β-caryophellene. Laboratory results indicated significant quantitative differences in the emission level of these indicator chemicals from infested plants compared to clean plants. Research greenhouse trials confirmed these results and also indicated that these differences are detectable six hours after initiation of infestation. The research greenhouse trials also indicated that is it possible to obtain information about T.ni population density, their location within the plant canopy and their feeding duration. A survey was conducted inside a commercial greenhouse. Indicator chemical emission levels, pest infestation status, environmental factors and operational practices were recorded. Pest infestation was found to have significant effect on the emission of indicator chemicals. A portable gas chromatograph was used for most phases of this research. This instrument was found suitable for fieldwork and monitoring rapid changes in the emission levels of plant volatiles. In general, these four chemical volatiles were found to be suitable indicators of T. ni infestation in greenhouse tomato plants.Land and Food Systems, Faculty ofGraduat