A Herbivory-Induced Volatile Disrupts Host Selection by Chilli Thrips, Scirtothrips dorsalis, on Strawberry

The chilli thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae), is an invasive and polyphagous pest that exhibits a broad host range. S. dorsalis relies on both visual and olfactory cues to locate and recognize its host plants and exhibits preference for young foliage. However, little is known about the specific cues mediating host selection by S. dorsalis. The objectives of this study were to: (1) identify herbivore-induced plant volatiles (HIPVs) produced by strawberry plants in response to S. dorsalis infestation versus mechanical damage; and (2) assess the behavioral response of S. dorsalis to uninfested versus infested strawberry plants. Laboratory olfactometer experiments revealed that S. dorsalis preferentially oriented to the volatiles from uninfested strawberry plants over those released by plants infested with conspecifics. In addition to the observed preference of S. dorsalis for uninfested strawberry plants, gas chromatographic-mass spectrometry revealed significant differences between the volatile compounds produced by uninfested strawberry plants and those produced by plants that had been infested with S. dorsalis in both the 'Florida Brilliance' and 'Florida Sensation' cultivars. Seventeen volatiles were identified from strawberry plants that were released in response to either mechanical or S. dorsalis feeding-induced damage; however, only three [(Z)-3-hexenyl acetate, cymene, and α-farnesene] were significantly elevated in S. dorsalis-infested plants relative to undamaged plants. One of these HIPVs, (Z)-3-hexenyl acetate, eliminated natural attraction of S. dorsalis to uninfested strawberry even though it did not act as a repellent when presented alone. Our results suggest a possible practical application of semiochemicals for managing S. dorsalis in strawberry.