Naturally occurring viruses ofDrosophilareduce offspring number and lifespan

Abstract

AbstractDrosophilaremains a pre-eminent insect model system for host-virus interaction, but the host range and fitness consequences of the drosophilid virome are poorly understood. Metagenomic studies have reported over 160 viruses associated withDrosophilidae, but few isolates are available to characterise theDrosophilaimmune response, and most characterisation has relied on injection and systemic infection. Here we use a more natural infection route to characterise the fitness effects of infection and to study a wider range of viruses. We exposed laboratoryD. melanogasterto 23 naturally occurring viruses from wild-collected drosophilids. We recorded transmission rates along with two components of female fitness: survival and the lifetime number of adult offspring produced. Nine different viruses transmitted during contact with laboratoryD. melanogaster, although for the majority, rates of transmission were less than 20%. Five virus infections led to a significant decrease in lifespan (D. melanogaster nora virus, D. immigrans nora virus, Muthill virus, galbut virus and Prestney Burn virus), and three led to a reduction in the total number of offspring. Our findings demonstrate the utility of theDrosophilamodel for community-level studies of host-virus interactions, and suggest that viral infection could be a substantial fitness burden on wild flies.