SHIC Highlights Vector Control Strategies for Pork Producers

As the US anticipates the annual surge in mosquito populations, pork producers are urged to implement robust control strategies to reduce mosquito populations near swine farms and minimize potential production impacts. Changes in environmental conditions, specifically during high rainfall seasons, may result in increased mosquito populations that can be a risk for emerging disease and other swine production challenges. Through global disease monitoring by the Swine Health Information Center, heightened awareness for mosquito control stems from the recent 2025 re-emergence of Japanese encephalitis virus in Australia, a stark reminder of the potential impact of this mosquito-borne pathogen.

In February 2025, JEV was reported at two piggeries in southern Queensland, Australia, marking the first detections of the virus in AU commercial swine since July 2022. With no cases detected in piggeries during 2023 or 2024, this re-incursion of JEV into Australian piggeries requires close monitoring. Recent detections in mosquito populations in Goondiwindi, Inglewood, and Monto, as well as in mosquito and feral pig populations in New South Wales, have raised concerns about further potential spread of JEV, particularly with wet season conditions increasing mosquito activity.
The US is currently negative for JEV, a mosquito-borne virus which has waterbirds as a natural reservoir host but is capable of infecting pigs, humans, and horses. As a transboundary disease risk for US introduction, JEV is transmitted through the bite of infected mosquitos and can cause reproductive failure, delayed farrowing, stillbirths, mummified fetuses, abortions and weak piglets in swine breeding herds. In December 2024, SHIC, along with the Foundation for Food & Agriculture Research, funded six research projects to enhance US prevention, preparedness, mitigation and response capabilities for JEV.

Understanding the biology and lifecycle of mosquitos can aid in the development of mitigation and control strategies to reduce risks of pathogen transmission as well as improve swine health and welfare. In August 2024, SHIC, in collaboration with the American Association of Swine Veterinarians, hosted a webinar entitled “Mitigation Strategies for Mosquitos as an Emerging Threat to Swine Health” in response to a significant increase in Midwest mosquito populations over the summer of 2024. The goals of the webinar were to understand the role of mosquitos as a vector for disease transmission and to take actions to control mosquito populations near swine farms.

As part of the webinar, Dr. Rademacher at Iowa State University shared information with producers detailing mosquito control strategies in Management of Site Insect Levels to Minimize Carcass Impact. This publication emphasizes an integrated pest management approach instead of reliance solely on chemical mitigation. Effective environmental management includes diligent control of standing water, a breeding ground for larvae, and vegetation management around buildings, which serve as resting sites for mosquitoes. Ventilation adjustments within barns can also play a crucial role in mosquito population control. He encouraged producers to consult with entomologists, who can offer expert pest identification and control strategies.

Site maintenance is also essential for effective mosquito mitigation. This includes establishing rock barriers for proper water drainage around buildings, maintaining short grass, and controlling weeds around all production facilities. Particular attention should be paid to curtain pockets, which can retain water. Operating stir fans at night during peak mosquito season in naturally ventilated barns and running tunnels at night in tunnel-ventilated barns can help mitigate mosquito populations within barns. Proper adjustment of misters, waterers, and sprinklers is vital to prevent water pooling in all barn types.

Chemical mitigation should be integrated into a comprehensive pest management strategy, with adult mosquito spraying considered the least effective component. Utilizing non-residual and residual sprays, with strict adherence to label instructions, is critical. Fogging devices, employing oil or water-based pyrethrins, are recommended for adult mosquito infestations within buildings. Residual sprays should be applied to resting surfaces, not directly on animals. To mitigate resistance, rotating the mode of action groups of chemical mitigants is essential.
Additional information regarding mosquito lifecycle and control strategies can be found here.

The Swine Health Information Center, launched in 2015 with Pork Checkoff funding, protects and enhances the health of the US swine herd by minimizing the impact of emerging disease threats through preparedness, coordinated communications, global disease monitoring, analysis of swine health data, and targeted research investments. As a conduit of information and research, SHIC encourages sharing of its publications and research. Forward, reprint, and quote SHIC material freely. For more information, visit http://www.swinehealth.org or contact Dr. Megan Niederwerder at [email protected] or Dr. Lisa Becton at [email protected].