Potential of Tomato Spotted Wilt Tospovirus Plant Hosts in Hawaii as Virus Reservoirs for Transmission byFrankliniella occidentalis(Thysanoptera: Thripidae)

Abstract

Five host plant species of tomato spotted wilt tospovirus (TSWV) were evaluated for their potential as virus acquisition and inoculation hosts for transmission by Frankliniella occidentalis. In addition, the feeding and oviposition preferences of F. occidentalis adults (nonviruliferous) for virus-infected and noninfected plants were compared. The presence of TSWV in E. occidentalis and host plants was detected by double antibody sandwich-enzyme-linked immunosorbent assay. Based on the efficiency of TSWV acquisition by F. occidentalis, the various host plants were ranked as follows (in descending order) : jimson weed, Datura stramonium; romaine lettuce, Lactuca sativa var. longifolia; and burdock (gobo), Arctium lappa. On the other hand, TSWV transmission by thrips inoculation was more efficient in D. stramonium, A. lappa, and golden crown-beard, Verbesina enceloides; than in L. sativa or cheeseweed, Malva parviflora. TSWV transmission from L. sativa to L. sativa showed the ability of F. occidentalis to initiate secondary spread within the crop. Likewise, virus transmission from D. stramonium to L. sativa and A. lappa or from L. sativa and A. lappa to noncrop hosts showed that E. occidentalis could spread TSWV from a weed to cultivated crops or vice versa. The presence of virus-infected plants has the potential to dramatically influence viruliferous thrips populations, because colonizing adults preferred landing and feeding on TSWV-infected plants. In addition, larval yields were significantly larger on diseased plants. The implications of these findings in the epidemiology of TSWV are discussed.