Observed and simulated population dynamics of Culex tarsalis in Nebraska

Background/Question/Methods

Human cases of West Nile virus (WNV) are most prevalent in the late summer and early fall moths in Nebraska. Surveillance efforts typically focus on this same time period. We studied the mosquito community during the late spring and early summer months as part of a National Science Foundation funded education program called “Research for Undergraduates in Theoretical Ecology” that provides an intensively mentored experience in both field and theoretical work. We trapped mosquitoes at six different locations in Lancaster County from May 14 to July 11, 2007. Culex mosquitoes were pooled to be tested for the presence of WNV using the Rapid Analyte Measurement Platform (RAMP^®) method. Culex tarsalis is the most important vector for WNV in Nebraska based on its abundance, its ability to contract and amplify the virus, and its willingness to feed on both avian and mammalian hosts. Early season mosquito population dynamics influence the transmission cycles of WNV, but are not well understood. We developed an individual-based population model to study the effects of weather variation on early season mosquito dynamics.

Results/Conclusions

The 2007 season was unusual with low numbers of mosquitoes late in the summer and few reported human WNV cases. RAMP tests confirmed the presence of WNV in one of 95 Culex pools. This model demonstrated the most sensitive parameters were survival probabilities for both adult mosquitoes and larvae. We also ran the model with 2007 weather data to determine if the unusual pattern of mosquito dynamics could be attributed to weather.