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, <i>Aphis gossypii</i> Glover, can cause yield loss in cotton, <i>Gossypium hirsutum</i> L. CLRDV has a variable incidence across the Cotton Belt, but factors underlying this variation are unknown. Field surveys of commercial cotton fields conducted in Alabama and Georgia from 2021-2022, allowed collection of data on <i>A. gossypii</i>, 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. <i>Aphis gossypii</i> 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 <i>A. gossypii</i> 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.