The 2009 ASHS Annual Conference

Greenhouse floriculture is an important segment of the American agriculture industry with bedding plants being an important commercial crop. As such, the horticulture industry has acknowledged the need to maintain the aesthetics and health of these crops through the reduction of insect feedings and the transmission of damaging plant viruses. With the identification of selectable plant traits that can confer resistance against insect feeding, a major diminution is made in plant damage and a corresponding reduction in insecticide applications throughout production. Impatiens (Impatiens walleriana) cultivars have been bred and selected over many generations for flower color, flower size, plant shape and habit and previous research has identified certain strains that are endowed with resistance to western flower thrips (WFT, Frankliniella occidentalis) infestation. To determine whether there exists an underlying biochemical factor to impatiens resistance to WFT beyond visual cues, experiments were undertaken to explore the hypothesis that emitted plant volatile compounds contribute to the observed resistance. In this research, the behavioral responses of adult WFT to volatiles from potted impatiens were investigated using a Y-olfactometer. Individual WFT ability to differentiate between purified air and volatile compounds of whole impatiens plants was determined. Using purified air and chrysanthemums (Chrysanthemum x morifolium, ‘Chesapeake’) as controls, the simple experimental design allowed for comparing four impatiens lines varying in resistance and susceptibility. The dynamic headspace volatile components of the plants and controls were then analyzed by capillary gas chromatography/ mass spectrometry (GC/MS). The results discussed herein demonstrate that different breeds of impatiens have variations in the production of volatile compounds. This variation has a dynamic impact on thrips behavior and response with some cultivars being more attractive than the purified air sample. We suggest that a complex interplay between the visual and biochemical cues confers WFT resistance to impatiens.