Population structure and Admixture of Culex pipiens complex in New York City using Genotyping By Sequencing

Abstract

The first cases of encephalitis associated with West Nile Virus (WNV) in New York City presented in 1999. Birds serve as the primary host for WNV and transmit the pathogen through mosquitoes of the Culex pipiens complex. The Culex pipiens form pipiens (Cx. pipiens f. pipiens) are exclusively ornithophilic (avian feeding) and require blood meal in order to reproduce. Cx. pipiens f. molestus are mammophilic and feed almost exclusively on mammals. WNV transmission to mammals occurs through a succession of feeding between an infected bird and subsequent mammal. While the two forms of Cx. pipiens have preferential food sources, they are capable of hybridizing and become indiscriminate in blood meal. Biosurveillance and clinical presentation in humans has been consistent since the introduction of WNV 20 years ago. While these two forms are physically identical, they differ fundamentally in behavior. Traditionally, a single locus STR (CQ11) has been the defining disambiguator of the two forms. However, this does not illustrate any level of hybridization that would provide insight to bloodmeal preference. Understanding the amount of admixture within NYC populations can aid in the identification of these forms and in vector control processes. This study uses Genotyping by Sequencing (GBS) through Restriction site associated DNA Sequencing (RAD‐Seq) in order to identify the level of admixture within the NYC Culex populations as well as the levels of ancestral states. Admixture analysis has identified unique SNPs that illuminates some underlying behavioral differences between the two forms, as well as evolutionary divergence.