Biology subjects

Fay, R. L.

Publications and source records attributed to Fay, R. L..

5 recordsLinked to original sources

bioRxiv2026

Bird functional dispersion predicts dengue vector presence across tropical working landscapes in Costa Rica

Identifying reliable indicators of dengue vector habitat is critical for proactive surveillance and spatially targeted vector control. Bird communities are sensitive to habitat quality and landscape condition, and their functional diversity may track ecological conditions that support Aedes mosquito populations. We tested whether bird functional diversity predicts dengue vector presence across two working landscapes in Costa Rica, comparing bird-based predictors against landscape composition, vegetation structure, and plant diversity. Bird functional dispersion (FDis), the spread of species in multidimensional trait space, was the top-ranked predictor for Ae. aegypti and Ae. albopictus larval presence and for adult Ae. aegypti, outperforming all other predictor classes. Probability of presence declined with increasing FDis, where functionally homogeneous bird communities, characteristic of disturbed landscapes, co-occur with higher vector presence, consistent with shared habitat filtering. Functional diversity estimations may offer a practical signal for identifying habitats at elevated dengue vector risk.

ecology↗

bioRxiv2026

Species-specific susceptibility and low transmission of the historical Japanese encephalitis virus Nakayama strain in North American Culex mosquitoes

Japanese encephalitis virus (JEV) is an emerging mosquito-borne flavivirus with potential for geographic expansion, yet the risk of establishment in North America remains poorly characterized. We assessed vector competence of three North American Culex species (Cx. pipiens, Cx. quinquefasciatus, and Cx. tarsalis) for the JEV Nakayama strain, isolated from human brain in 1934 in Japan, across five constant temperatures (15, 20, 25, 30, and 33{degrees}C) at 4, 7, and 14 days post-feeding, quantifying infection, dissemination, and transmission rates. Vector competence was low but non-zero across all species. Cx. pipiens showed higher infection rates than the other species, whereas Cx. quinquefasciatus and Cx. tarsalis were minimally susceptible under these experimental conditions. Temperature had limited effects on infection and no detectable effects on dissemination or transmission. These findings suggest limited transmission potential of JEV Nakayama in North America, with Cx. pipiens as a relatively permissive vector.

molecular biology↗

bioRxiv2026

Mosquito infection-mediated trait variation alters temperature-dependent transmission of West Nile virus

Rising global temperatures are reshaping species interactions and the ecological conditions governing vector-borne disease transmission. Although previous studies show that West Nile virus (WNV) infection alters mosquito longevity, fecundity, blood-feeding behavior, and the thermal performance of these traits, trait-based R models largely rely on data from uninfected mosquitoes, implicitly assuming homogeneous vector populations. This overlooks infection-induced trait variation that may influence transmission dynamics. Here, we examined how temperature, infection status, and viral strain interact to shape transmission potential for WNV in Culex pipiens. Life-history traits of WNV-exposed and unexposed mosquitoes were measured across constant temperatures ranging from 10{degrees}C to 33{degrees}C, as well as under a fluctuating temperature regime of 25{degrees}C {+/-} 5{degrees}C. These data were used to generate thermal performance curves and estimate temperature-dependent relative R across treatments. Infection altered the thermal performance of mosquito life-history traits, vector competence, and overall transmission potential. We also found evidence for a bimodal effect of temperature on vector competence, potentially driven by tradeoffs between viral replication and mosquito immune responses. Incorporating infection-sensitive traits into relative R calculations reduced estimated transmission intensity across much of the thermal range without shifting thermal optima or limits, suggesting that current models may overestimate transmission.

microbiology↗

bioRxiv2025

The impact of climate change on transmission season length: West Nile virus as a case study

BackgroundClimate change is accelerating the spread of temperature-sensitive vector-borne diseases such as West Nile virus (WNV), the most widespread mosquito-borne disease in the United States, with 2,400 reported cases in 2024. In New York State (NYS), where WNV first emerged in the U.S., mean temperatures have increased by 1.4{degrees}C since the early 1900s. Although temperature is a well-established driver of WNV transmission, its effect on transmission season length remains poorly quantified. This study examines whether WNV transmission seasons have lengthened in NYS and whether these changes are associated with increased disease risk, shifts in seasonal timing, and anthropogenic climate change. MethodsWe integrated daily county-level observational data from 1999-2024, including temperature, mosquito surveillance, and human case data, with climate model simulations spanning 1850-2024 to assess trends in transmission season length. FindingsBased on observed temperature suitability, the WNV transmission season in NYS has lengthened by an average of 20 days over the past 25 years, beginning 3.8 days earlier and ending 16.3 days later. Longer transmission seasons are positively associated with higher WNV prevalence in both mosquito vectors and humans. While such changes could occur in the absence of global warming, climate model analyses indicate that the observed increase in season length is 6.4 times more likely under historical climate forcing since 1900 than under pre-industrial conditions. InterpretationThese findings demonstrate that climate change is reshaping the phenology and burden of WNV transmission. FundingSupported by NIH, NSF, Stanford University, and the Fogarty International Center. Research in ContextO_ST_ABSEvidence before this studyC_ST_ABSWe searched Google Scholar for publications from 1999 to 2024 using the term "West Nile virus and season length," yielding 18,200 results. Previous studies focused on how climatic factors affect transmission and its seasonality in the United States, but none assessed how climate change influences transmission season duration. We analyzed over two decades of data to link extended WNV transmission seasons with increased vector and human prevalence. Additionally, we evaluated the causal role of climate warming using simulated climate data and counterfactual analyses. Added value of this studyUsing daily temperature and WNV case data from 1999- 2024, we found that the WNV transmission season in NYS has lengthened by an average of 20 days. The season now begins 3.8 days earlier and ends 16.3 days later. Longer seasons were associated with higher prevalence in mosquitoes and humans. Climate model simulations indicate that human-driven greenhouse gas emissions have significantly extended the WNV season, making observed trends in season length, onset, and conclusion 6, 2, and 16 times more likely, with implications for mosquito infection and human disease risk. Implications of all available evidenceOur findings suggest that climate change is lengthening WNV transmission seasons, a phenomenon likely relevant to other temperature-sensitive vector-borne diseases. As warming continues, extended transmission seasons may amplify risks for WNV and other vector-borne diseases, underscoring the need for climate-adaptive public health surveillance and intervention strategies.

ecology↗

bioRxiv2025

Temperature influences West Nile virus evolution and adaptation

Abstract bodyWest Nile virus (WNV), the most common mosquito-borne disease in the continental U.S., is vectored by Culex spp. mosquitoes. Since its introduction to New York State (NYS) in 1999, WNV has become endemic. NYS temperatures have risen by 0.14{degrees}C per decade since 1900, with larger increases linked to higher WNV transmission. Using surveillance and sequencing data, we find a significant correlation between rising temperatures, increased WNV genetic diversity, and higher prevalence. Given the experimentally demonstrated role of temperature influencing WNV fitness, we hypothesized that contemporary strains should exhibit greater fitness in mosquitoes at higher temperatures compared to historic strains. To test this, we analyzed genetically distinct WNV strains from mosquitoes collected during recent warm summers (2017 and 2018) and cooler historic summers (2003 and 2004). Assessing Culex pipiens vector competence and calculating the relative R at 20{degrees}C, 24{degrees}C, and 28{degrees}C, we found that contemporary strains exhibit higher transmission potential at increased temperatures. Our results show that contemporary WNV strains possess greater phenotypic and genotypic diversity, facilitating the emergence of strains with enhanced transmission potential in a warming climate.

molecular biology↗