Diversifying agricultural systems by growing more than one crop species in an area can decrease pest and disease pressure and increase crop yields. However, there is a lack of information on how crop diversity at larger spatial scales influences pest and disease pressure. Here, we investigated how landscape-scale crop diversity affects aphid vector communities and prevalence of non-persistently transmitted potato virus Y (PVY). To test the influence of landscape-scale crop diversity on PVY prevalence and aphid communities, we conducted a field study during the 2020 and 2021 field seasons in the San Luis Valley, Colorado where we quantified aphid communities and PVY incidence at multiple sites. We then determined the association of aphid species richness and abundance and PVY incidence with landscape variables (crop diversity metrics and percentage cover of crop species) within 1, 2 and 3 km buffers from study sites. Higher crop diversity (measured as Shannon diversity index) led to decreased aphid species richness at a 3 km buffer in the 2021 field season. Percentage of alfalfa was positively associated with aphid species richness in 2020 and aphid abundance in 2021 within a 1 km buffer. Higher crop diversity led to increased PVY incidence at a 2 km buffer in 2021 and 3 km buffer in 2020 and 2021. At a 3 km buffer in 2021, we found a positive influence of crop species richness on PVY incidence and a negative influence of crop species evenness on PVY incidence. Also in 2021, we found a positive influence of percentage of potato (virus host) on PVY incidence and a negative influence of percentage of barley (virus non-host) on PVY incidence.

Synthesis and applications: In summary, we found that landscape-scale crop diversity impacts plant virus prevalence at spatial scales of >1 km. This suggests that potato growers could reduce PVY prevalence by geographically isolating potato fields from other potato or other PVY-hosts. Crop diversity had a negative influence on aphid vector communities so growers could reduce risk of virus spread by aphid vectors by using certified potato seed in a diversified landscape.

A two-year field study (during the years 2020 and 2021) was conducted in the San Luis Valley, Colorado, a major potato producing region in the United States. Potato fields were sampled and tested for the presence of PVY biweekly (i.e., once every two weeks) at 17 fields (eight fields in 2020 and nine fields in 2021) using TAS-ELISA, and aphid communities were sampled weekly, using yellow pan traps, at 10 sites during both years. Potato fields were pivot-irrigated and most fields were either ~24-25 hectares or ~49-54 hectares in area. The mean distance from sampled potato plants to corresponding aphid traps was 567.4 m. Each sampling site, for both aphids and PVY, was at least 1.5 km away from the next closest sampling site. In 2020, one field (“6N6E”) was sampled which did not have corresponding aphid traps; this site was included for tests of PVY-landscape associations but not PVY-aphid abundance or species richness associations. Also in 2020, one field (“RS-1”) was composed of the PVY-resistant potato variety “Rocky Mountain Russet”, so this field was excluded from analyses.

This dataset contains .csv files of weekly values of abundance and species composition of aphids from yellow pan traps at each trapping site, results from biweekly sampling and testing for PVY incidence in potato fields, and values of landscape composition surrounding aphid and PVY sampling sites, obtained from landscape composition data provided by the Rio Grande Water Conservation District. Associations between PVY incidence and aphid communities were determined using binomial (logit) generalized linear mixed-effects models (GLMM). Associations between PVY incidence and landscape composition were determined using logistic regression models. Associations between aphid communities and landscape composition were determined using linear regression models. Further details on statistical analyses can be found in Pitt et al. (2024), “Landscapes with higher crop diversity have lower aphid species richness but higher plant virus prevalence” published in Journal of Applied Ecology.