Investigation of responses of flower thrips and Orius insidiosus to TSWV- and TYLCV-induced volatiles in tomatoes

It is well-known that natural enemies are attracted to herbivory-induced plant volatiles (HIPVs). Similarly, previous research demonstrated that vectors of plant pathogens are attracted to plant volatiles induced by the pathogen that they transmit. The specificity of this response, however, is not well-known. We investigated the response of two thrips species, the western flower thrips, Frankliniella occidentalis Pergande, a vector of tospoviruses such as tomato spotted wilt virus (TSWV) and a non-vectoring species, the eastern flower thrips, F. tritici Fitch. Both species compete within the same flower, but they may respond differently to plant pathogen-induced volatiles, including those they do not transmit such as the Begomovirus tomato yellow leaf curl virus (TYLCV) transmitted by the sweet potato whitefly, Bemisia tabaci Gennadius. The minute pirate bug, Orius insidiosus Say, is a predator of thrips and may “eavesdrop” on these pathogen-induced volatiles which attract its prey. We investigated the response of 1) F. triciti (non-vectoring thrips species), 2) F. occidentalis (vectoring thrips species), and 3) O. insidiosus to TSWV- and/or TYLCV-infected hosts in choice tests. The non-vector F. tritici did not respond to pathogen-induced volatiles, whereas the vector F. occidentalis was attracted to both TSWV and TYLCV-infected hosts. Results indicated that the vectoring thrips species had a generalist response to virus-induced volatiles absent in the non-vectoring species. Orius insidiosus was also attracted to both pathogen-induced volatiles, indicating that they used similar cues to their prey to select their host.