Specificity of vectoring and non-vectoring flower thrips species to pathogen-induced plant volatiles

Insect-vectored plant pathogens are known to alter host-plant quality and associated cues, subsequently affecting the frequency of interactions with vectors and influencing pathogen transmission. It is unknown whether these changes deliver information highly specific to the vector and have evolved as a result of host manipulation or if they are more generalist indicator of plant status. In the current study, the responses of two thrips species, Frankliniella occidentalis Pergande, the vector of the tospovirus Tomato spotted wilt virus (TSWV) and a non-vectoring species, F. tritici Fitch, to pathogen-induced plant volatiles (PIPVs) in tomatoes were investigated. As the two species cohabit, and one is a vector of tospoviruses while the other is not, this system is perfectly suited to investigate the specificity of PIPVs to insect vectors. Both species were exposed to PIPVs of TSWV and the begomovirus Tomato yellow leaf curl virus (TYLCV) transmitted by the sweet potato whitefly, Bemisia tabaci Gennadius. Frankliniella tritici did not respond to PIPVs. F. occidentalis was attracted to both TSWV- and TYLCV-infected plants and showed no preference between plants infected by either virus. Volatiles from TSWV- and TYLCV-infected plants were collected and identified using GC–MS. Principal component analysis showed a clear differentiation between the volatiles of the uninfected and infected tomatoes. There was no differentiation between the volatile profiles of the two virus-infected tomatoes, suggesting that PIPVs may be a by-product of viral infection that elicit a generalist response in F. occidentalis and are likely not the result of host manipulation.