Virus infection alters the predatory behavior of an omnivorous vector

Th e interactions between parasites and their hosts can cause profound changes in host behavior, including changes that can alter other trophic interactions. Th e western fl ower thrips Frankliniella occidentalis is an important omnivorous insect vector of Tomato spotted wilt virus (TSWV), which infects crops worldwide and also infects its thrips vector. Here, we show that tospovirus-infected female thrips become more predaceous, illustrating how the functional role of omnivores may change in response to pathogen infection. Our fi ndings support the hypothesis that increased predation among virus-infected female thrips compensates for the detrimental eff ects of virus infection. Because predatory behavior is unlikely to increase virus transmission to plants, it is doubtful that this shift in feeding behavior is due to an adaptive parasite manipulation of vector behavior. In this study, increases in predatory behavior were observed in female thrips, but not in male thrips. Th is sexually dimorphic compensatory response indicates that male and female thrips utilize diff erent feeding strategies to compensate for parasite infection, the expression of which is constrained by resource availability. Our fi ndings demonstrate a novel, but potentially common pathway by which viruses can infl uence the structure of trophic interactions in food webs.