Thrips tabaci: an ambiguous vector of TSWV in perspective

Abstract: The transmission ability of Thrips tabaci, one of the first recognized vectors of Tomato spotted wilt virus (TSWV), is a matter of much discussion. Although originally considered as an important vector, it failed to transmit TSWV in several laboratory tests. However, destructive outbreaks of TSWV in the tobacco crops of East Europe and the Balkan Peninsula have for long been attributed to T. tabaci. Recent results have shown that a large diversity exists in the competence to transmit TSWV or other tospoviruses between the parthenogenetic and sexual populations of this haplodiploid species. Arrhenotokous, sexual, populations, are either poor or very efficient vectors of TSWV. Several populations on leeks were poor vectors of TSWV and did not transmit Tomato chlorotic spot virus (TCSV), Groundnut ring spot virus (GRSV) or Impatiens necrotic spot virus (INSV), while others proved to be very efficient vectors of Iris yellow spot virus (IYSV). Arrhenotokous populations from tobacco were highly effective in transmitting TSWV in laboratory tests as well as in the field. TSWV was acquired by both first and second larval stages of a T. tabaci population from tobacco, and most thrips started to transmit after becoming adults. The dynamics of TSWV spread by arrhenotokous T. tabaci studied in tobacco fields, showed that primary infections play a major role in the development of epidemics. Large-scale surveys associated this thrips species with TSWV infections in several wee