Cotton-Dominated Landscapes, Vector Abundance, and Temperature Influence Cotton Leafroll Dwarf Virus Incidence in Cotton.

Understanding how biotic and abiotic factors influence vector-borne pathogen spread is essential for effective management. Cotton leafroll dwarf virus (CLRDV), transmitted by the cotton aphid, Aphis gossypii, can cause yield loss in cotton, Gossypium hirsutum CLRDV has a variable incidence across the U.S. Cotton Belt, but factors underlying this variation are unknown. Field surveys of commercial cotton fields conducted in Alabama and Georgia from 2021 to 2022 allowed for collection of data on A. gossypii, natural enemies, CLRDV weed hosts, CLRDV incidence, landscape composition, temperature, and precipitation. A structural causal modeling analysis using a directed acyclic graph framework was used to test the significance of these factors on CLRDV incidence in cotton while controlling for potentially confounding effects. A. gossypii abundance, prevalence of cotton in the landscape, and temperature had significant and positive effects on CLRDV incidence, whereas other variables were not significant. Temperature had a significant and positive effect on A. gossypii abundance, which likely contributed to the overall effect of temperature on CLRDV incidence. Cotton is a host for both the vector and virus, which may increase the abundance of both. Novel findings from this study identify factors associated with regions at high risk for CLRDV. Future work can leverage these findings to better predict the spatial and temporal variability in disease incidence.