Landscape composition of crops is associated with potato virus Y prevalence

Landscape composition affects transmission of vector-borne plant viruses. Aphid-vectored potato virus Y (PVY) is one of the most damaging and economically important plant viruses, has a large host range, and is transmitted by approximately 65 species of aphids. The goal of our study was to determine associations of crop species composition (percent cover) and crop species diversity (Shannon Diversity Index) with PVY transmission within a landscape. We conducted a two-year (2020 and 2021) field study where aphid populations and PVY incidence were surveyed around potato fields in the San Luis Valley in Colorado. PVY incidence showed a significant positive association with aphid abundance and species richness during 2021, but there was no observed association during 2020. Results from spatial analyses of surrounding landscapes did not reveal any associations between crop species composition or diversity with aphid populations. However, a significant positive association between potato and PVY incidence was observed at all three spatial scales (i.e.,1 km, 2 km, and 3 km). Moreover, PVY incidence had a significant positive association with crop diversity at two different spatial scales (2 km and 3 km). Together, these results show that potato acreage and crop diversity, within a landscape of monocultures, are associated with increased PVY prevalence. Because non-colonizing vectors (those that probe but do not host on potato) are important for PVY spread, we are in the process of performing molecular gut content analysis with aphid samples to identify previous host plants of aphids that could be important for PVY spread.