Forest proximity shapes host-feeding patterns of Culex erraticus , a potential vector of eastern equine encephalitis virus, in Illinois

Abstract

Mosquito host-feeding patterns strongly influence pathogen transmission potential, but landscape drivers of host use remain poorly understood for many generalist vectors. We examined whether landscape composition and spatial configuration predict blood-feeding patterns of Culex erraticus collected from natural areas across Illinois, USA. Specifically, we tested whether land-cover composition and distance from key landscape features, including forest edge, are associated with host-use shifts relevant to zoonotic pathogen transmission. Blood-fed females were identified morphologically, vertebrate hosts were determined by mitochondrial Cytochrome c Oxidase Subunit I (COI) amplicon sequencing, and landscape variables were quantified within a 1,000-m radius around each site. Among identified blood meals, Cx. erraticus fed primarily on mammals (73.1%), followed by birds (21.2%), reptiles (5.0%), and amphibians (0.7%), with white-tailed deer and humans dominating mammalian meals. The best-supported generalized linear model (GLM) for bird versus mammal feeding retained mean distance to forest edge and natural cover as predictors, although only distance to forest edge was significant, with mammal feeding declining as signed distance to forest edge became more positive, that is, farther into non-forested habitat. Among mammalian meals, the best-supported GLM for human versus non-human mammal feeding retained mean distance to forest edge as the sole predictor, with human feeding increasing at greater positive distances from forest edge. These results indicate a host shift across the forest-edge gradient and suggest that fine-scale landscape structure, particularly forest proximity, predicts host use in Cx. erraticus. This pattern may help explain spatial variation in human exposure risk to zoonotic pathogens.