Response of western flower thrips, Frankliniella occidentalis and its predator Amblyseius cucumeris to chrysanthemum volatiles in olfactometer and greenhouse trials.

In olfactometer assays, the predatory mile Amblyseius cuciiiiieris (Oudemans) recorded a significantly higher response to volatiles from chrysanthemum, Dendranthema morifolium plants infested with western flower thrips (WFT), Frankliniella occidentalis (Pergande) than to volatiles from healthy plants. This increased attraction was attributed to the presence of higher amounts of Germacrene-D in WFT-infested plants. In choice experiments using synthetic volatiles, the predator remained longer in the olfactometer treated with 50 ng Germacrene-D and made many entries at 500 mg. Preferential attraction of WFT to healthy chrysanthemum flower buds was observed, and attributed to the significantly higher amounts of (E)-β-farnesene found in the buds compared to leaves and open flowers. This attraction peaked at 100 ng/pl (E)-β-farnesene. In greenhouse experiments, blue sticky traps with 500 ng (E)-β-farnesene or 1000 mgf>-anisaldehyde attracted 32.3% and 27.5% more WFT than the untreated controls, respectively. The prospects of using Germacrene-D in improving the attraction of A. cucumeris to whole chrysanthemum plants and (E)-β-farnesene in monitoring WFT, are discussed.