Effect of artificial light on collection of West Nile vectors and disease surveillance in northern Colorado

To evaluate whether the presence of clear incandescent light was attractive or refractive to adult host-seeking mosquitoes in Northern Colorado, a Bayesian hierarchical model was created to measure differences in trap effectiveness based on the presence or absence of phototactic cues.  A total of 96 CDC miniature light traps (with and without light) were set across 4 locations in Northern Colorado between 1 June 2020 and 18 August 2020.  Culex mosquitoes (Diptera: Culicidae) accounted for 81% of all collections in this study with two vectors of West Nile virus being represented.  The probability of catching a mosquito was reduced for both disease vector species but the difference was not statistically significant for Culex tarsalis since the credibility intervals overlap between treatments.  The clear reduction in the number of Culex pipiens caught when these traps were equipped with an incandescent light indicate negative phototactic behavior and underestimation with current surveillance strategies.   Removal of light from these traps may aid our understanding of these species’ distribution within the environment, improve collection efficiency, and help guide implementation of targeted control measures used in public health mosquito control.