Aggregation pheromones released by nymphs of the stick tea thrips (Dendrothrips minowai): identification and analysis of their potential utility for controlling thrips in tea plantations

Abstract

BACKGROUND The stick tea thrips, Dendrothrips minowai Priesner, is one of the most important sucking pests that seriously infest tea plants (Camellia sinensis) in China. Obvious D. minowai nymph aggregation behaviors are typically detected in tea plantations. The objectives in our study were to identify D. minowai aggregation pheromones and evaluate their potential utility for controlling thrips infestations in tea plantations. RESULTS Dendrothrips minowai nymphs, females, and males were significantly attracted to nymph volatiles rather than the volatiles secreted by females and males in H-tube olfactometer assays under laboratory conditions. Our gas chromatography-mass spectrometry analysis of volatiles collected from D. minowai revealed that nymphs can produce dodecyl acetate and tetradecyl acetate. Additionally, the D. minowai females and males responded positively to dodecyl acetate, tetradecyl acetate, and the mixture (dodecyl acetate : tetradecyl acetate = 1 : 1.5) according to in behavioral experiments under laboratory conditions. Moreover, both aggregation pheromones and the mixture increased the number of D. minowai adults on sticky traps by 0.9- to 2.5-times (compared with the traps containing the solvent control) in tea plantations. Most importantly, at 10 days after adding sticky traps with D. minowai aggregation pheromones to tea plantations, the number of adult thrips per 100 leaves decreased by 57–75%, which was significantly higher than those of 39% decrease induced by the solvent control. CONCLUSION Dodecyl acetate and tetradecyl acetate were identified as D. minowai nymph-produced aggregation pheromones that can significantly attract conspecifics under laboratory conditions. More importantly, combining the aggregation pheromones with sticky traps can significantly decrease the thrips population in tea plantations. The findings of this study on thrips pheromones may be useful for developing new methods for managing thrips that do not require potentially harmful insecticides.