Investigating habitat preferences and host-feeding behavior of mosquito disease vectors on commercial swine farms in the USA.

Abstract

BACKGROUND: Mosquito feeding behavior and habitat preferences strongly influence arbovirus transmission, particularly for viruses where swine serve as amplifying hosts. The high density of pigs in commercial operations poses a potential risk for severe outbreaks if mosquito-borne pathogens were to be introduced. This study characterizes habitat preferences and feeding behavior of mosquito species on commercial swine farms in the USA. METHODS: Overall, ten farms (five sow and five wean-to-market [WTM] farms) were sampled biweekly from June to October 2024. At each farm, resting mosquitoes were collected outdoors using aspirators, while light traps were deployed indoors and outdoors to trap host-seeking mosquitoes. Blood-fed females from all capture methods underwent DNA extraction, polymerase chain reaction (PCR), and Sanger sequencing to identify mosquito species and vertebrate hosts. Generalized linear mixed models were used to evaluate associations between habitat, location, and calendar period with the abundance of resting and blood-fed mosquitoes. RESULTS: In this study, 3009 resting mosquitoes (both males and females) were collected. Vegetation habitats consistently harbored more resting and male mosquitoes than water bodies (P&#x2009;&#x2264;&#x2009;0.02), on both sow and WTM farms. A total of 444 blood-fed female mosquitoes were captured, of which 25.7% (114/444) were captured on sow farms and 74.3% (330/444) on WTM farms. On WTM farms, the abundance of blood-fed mosquitoes was significantly higher indoors than outdoors (P&#x2009;<&#x2009;0.01). Across production systems, the dominant blood-fed species were Anopheles quadrimaculatus (n&#x2009;=&#x2009;157), Culex pipiens (n&#x2009;=&#x2009;105), Aedes vexans (n&#x2009;=&#x2009;65), Culex salinarius (n&#x2009;=&#x2009;46), and Anopheles punctipennis (n&#x2009;=&#x2009;45). Pigs accounted for the majority of blood meals (n&#x2009;=&#x2009;384), followed by white-tailed deer (n&#x2009;=&#x2009;38), cattle (n&#x2009;=&#x2009;11), and birds (n&#x2009;=&#x2009;11). The probability of mosquitoes feeding on pigs compared with other hosts was significantly higher from late June through mid-September (P&#x2009;<&#x2009;0.01). CONCLUSIONS: This study provides baseline data on mosquito habitat preferences and feeding behavior on US commercial swine farms. Routine mosquito vector surveillance and targeted control measures, both indoors and in surrounding habitats, should be integrated into herd biosecurity programs to mitigate mosquito-associated health risks in commercial swine operations.