Behavioral Responses of Thrips hawaiiensis (Thysanoptera: Thripidae) to Volatile Compounds Identified from Gardenia jasminoides Ellis (Gentianales: Rubiaceae).

Thrips hawaiiensis is a common thrips pest of various plant flowers with host preference. Plant volatiles provide important information for host-searching in insects. We examined the behavioral responses of T. hawaiiensis adults to the floral volatiles of Gardenia jasminoides Ellis, Gerbera jamesonii Bolus, Paeonia lactiflora Pallas, and Rosa chinensis Jacq. in a Y-tube olfactometer. T. hawaiiensis adults showed significantly different preferences to these four-flower plants, with the ranking of G. jasminoides > G.jamesonii > P. lactiflora ≥ R. chinensis. Further, 29 components were identified in the volatile profiles of G. jasminoides, and (Z)-3-hexenyl tiglate (14.38 %), linalool (27.45 %), and (E3,E7)-4,8,12-trimethyltrideca-1,3,7,11-tetraene (24.67 %) were the most abundant. Six-arm olfactometer bioassays showed that T. hawaiiensis had significant positive responses to (Z)-3-hexenyl tiglate, linalool, and (E3,E7)-4,8,12-trimethyltrideca-1,3,7,11-tetraene tested at various concentrations, with the most attractive ones being 10-3 μL/μL, 10-2 μL/μL and 100 μg/μL for each compound, respectively. In pairing of these three compounds at their optimal concentrations, T. hawaiiensis showed the preference ranking of (Z)-3-hexenyl tiglate > linalool > (E3,E7)-4,8,12-trimethyltrideca-1,3,7,11-tetraene. Large numbers of T. hawaiiensis have been observed on G. jasminoides flowers in the field, which might be caused by the high attraction of this pest to G. jasminoides floral volatiles shown in the present study. Our findings shed light on the olfactory cues routing host plant searching behavior in T. hawaiiensis, providing important information on how T. hawaiiensis targets particular host plants. The high attractiveness of the main compounds (e.g., linalool, (E3,E7)-4,8,12-trimethyltrideca-1,3,7,11-tetraene, particular (Z)-3-hexenyl tiglate) identified from volatiles of G. jasminoides flowers may be exploited further to develop novel monitoring and control tools (e.g., lure and kill strategies) against this flower-inhabiting thrips pest.