Assistant Professor University of Nevada, Las Vegas, Nevada, United States
Abstract: The establishment of Aedes (Ae.) aegypti, the major arboviral vector species, in desert cities poses a novel public health risk. In 2017, the Southern Nevada Health District (SNHD) reported the first detection of this invasive species in Clark County, Nevada. To predict the spatiotemporal expansion of Ae. aegypti in Southern Nevada, we analyzed 23,572 mosquito trap deployments from 2017-2024 across 82 ZIP codes in Clark County. To investigate environmental drivers of vector abundance, a hybrid approach of unsupervised and supervised machine learning regression models was developed using composite demographic, bioclimatic and ecological remote sensing data. Longitudinally whole genome sequencing data was generated to determine population genetic origin. Population structure analyses revealed four genetic clusters, including Las Vegas and North Las Vegas specimens that aligned most closely with Ae. aegypti from Fresno County, California, suggesting a shared source or gene flow along the I-15 corridor. Henderson specimens formed a distinct cluster, while three Las Vegas outliers indicated possible secondary invasion events. Spatiotemporal modeling of SNHD trap data (3180 trap records, 18,833 individuals collected) examined ~92 environmental predictors, demonstrating rapid expansion from 4 ZIP codes in 2017 to 57 ZIP codes in 2024. Vapor pressure, total precipitation and human modification were the strongest drivers of Ae. aegypti abundance. Ae. aegypti rapidly colonized xeric urban habitats in Southern Nevada via multiple introductions, with expansion shaped by vegetation, climate, and human modification of the built environment.
