Spatial and temporal variation in vector competence of Culex pipiens and Cx. restuans mosquitoes for West Nile virus.

Vector competence, the probability that a vector will transmit a pathogen after feeding on an infected host, is known to vary among vector species, populations, days since feeding, and temperature during the extrinsic incubation period. However, the extent of spatio-temporal variability and consistency in vector competence of populations is not known. We examined vector competence of Culex pipiens Linnaeus and Cx. restuans Theobald mosquitoes for West Nile virus collected over 3 years from 17 sites to measure spatial and temporal scales of variation in vector competence. We found extreme variation with 0-52% of mosquitoes transmitting West Nile virus at a single site between different sampling periods, and similar variation across populations. However, we also found that within a smaller geographic range, vector competence varied somewhat synchronously, suggesting that environmental and population genetic factors might influence vector competence. These results highlight the spatio-temporal variability in vector competence and the role of local processes.