Dr. Meredith Anderson, a veterinarian and PhD candidate in the Ecology and Evolutionary Biology Program at the Texas A&M University College of Veterinary Medicine and Biomedical Science, is uncovering a hidden risk in the natural world: how pesticide exposure weakens birds’ immune systems and could make them ideal carriers of zoonotic diseases. “Dr. Anderson’s clinical veterinary background provides an important foundation to now ask questions about individual, population, and community-level impacts of pesticide exposure in her PhD program,” says Dr. Sarah Hamer, Director of the Schubot Center and a key collaborator with UTMB. “Her work is a great combination of field-based observational studies and aviary-based manipulative experiments. Her research in avian ecotoxicology looks at the effects of neonicotinoid pesticides on bird health and their role in spreading zoonotic diseases—a project that sits at the heart of the One Health concept.” Dr. Anderson’s journey into avian research didn’t start in a lab—it started in the field. A self-proclaimed bird enthusiast, she found her passion for ornithology in her university’s birding club. This soon turned into scientific curiosity, and she began working on wild bird population surveys before going to veterinary school. “The club was small, but the members’ passion for birds and nature was infectious,” she recalls. “I found myself wanting to learn everything I could about avian research.” Later on, as a veterinary student, she was introduced to One Health, the concept that connects human, animal and environmental health. It was a natural fit for her growing interests— One Health’s mission allowed her to merge her love of wildlife with the study of disease, physiology, and environmental health. This approach and one statistic influenced the direction of her current research.
In 2019, a landmark study reported that North America had lost 30% of its bird populations since 1970. The number was huge and led to more questions; questions no one had definitively answered. Anderson became determined to find out if pesticide exposure was a contributing factor to avian population declines. Neonicotinoid pesticides, used in agriculture and urban landscaping, are the most common environmental contaminants affecting birds. These chemicals enter the environment through treated seeds, contaminated water, soil, and insect prey – often in ways we overlook. Dr. Anderson’s research looks at neonicotinoids in birds at individual and population levels. Her first study is already published and examined ecological, temporal, and spatial factors affecting pesticide exposure in Texas bird populations. “We found that birds sampled in spring and fall had higher incidences of pesticide exposure,” she explains. “Juvenile birds were also at greater risk than adults. Among species, American robins and red-winged blackbirds had the highest exposure levels.” These results are important for conservationists and policymakers to know which species, seasons and habitats are most at risk of pesticide contamination.
Dr. Anderson’s current study asks the One Health question: How does pesticide-induced immunosuppression impact a bird’s ability to spread zoonotic disease?
Her experimental work at the Schubot Center for Avian Health looks at how imidacloprid, a common neonicotinoid pesticide, affects a bird’s immune system and its ability to transmit West Nile virus and Salmonella Typhimurium – two pathogens of human health concern. “Neonicotinoids are known to suppress immune function in birds,” she explains. “This could increase their susceptibility to disease and even influence how they spread infections across ecosystems.” Although the study is still ongoing, the findings will ultimately impact public health and wildlife conservation. Pesticides can weaken a bird’s immune system and lead to larger zoonotic spillover events – potentially increasing the risk of disease transmission from wildlife to humans. Neonicotinoids are also linked to the decline of insect populations, disruption of food chains, and an overall negative impact on ecosystems. “Most terrestrial birds eat insects at one or more life stages (along with many other wildlife species),” Dr. Anderson says. “In fact, multiple studies have documented parallel declines of birds and insects in areas of high neonicotinoid use.”
Her research informs conservation efforts and policy discussions around pesticide use. In the US, states like New York and Vermont are banning neonicotinoid coated seeds, following Quebec, Canada reduced pesticide use on corn and soybeans from 100% to less than 0.5%. By revealing the risks of neonicotinoid exposure Dr. Anderson hopes her work will guide future policy to reduce environmental contamination and protect bird populations. As she nears the end of her dissertation Dr. Anderson is still passionate about exploring the intersection of chemical exposure, wildlife health and ecosystem resilience. Next, she plans to expand her research to other declining bird populations, wetland ecosystems, and chemical pollutants beyond pesticides. “If I change focus, I think it would be to address how chemical contaminants are harming specific groups of birds declining most rapidly,” she says. Understanding the effects of chemical contaminants is not just critical for birds but for the entire ecosystem. Through Dr. Anderson's work, she’s uncovering the hidden links between wildlife, environmental change, and human health. In the process, she’s building a future where science serves both public health and conservation.
The Schubot Center for Avian Health
Located on Texas A&M’s campus, The Schubot Center for Avian Health (Home - Schubot Center for Avian Health) serves as a hub for avian health expertise, research models, and BSL-2 facilities designed for bird studies. “We have lots of avian health expertise, avian models for study, and BSL-2 suites for birds,” says Dr. Hamer. “We are happy to collaborate with those inside and outside of TAMU.”
Acknowledgment:
A special thank you to Dr. Meredith Anderson, Dr. Sarah Hamer, and the Schubot Center for Avian Health researchers for their work to understand the complex connections between environmental health, wildlife conservation, and public health.
References:
- Rosenberg, K. V., et al. (2019). Decline of the North American avifauna. Science, 366(6461), 120-124.
- Gibbons, D., Morrissey, C., & Mineau, P. (2015). A review of the direct and indirect effects of neonicotinoids and fipronil on vertebrate wildlife. Environmental Science and Pollution Research, 22, 103–118.
- Hallmann, C. A., et al. (2014). Declines in insectivorous birds are associated with high neonicotinoid concentrations. Nature, 511, 341-343.
- Mineau, P., & Palmer, C. (2013). The impact of insecticides on birds: A technical review. American Bird Conservancy.
- U.S. Geological Survey (USGS). Pesticide National Synthesis Project. https://www.usgs.gov/centers/naWQA/pesticides
- Dr. Meredith Anderson ResearchGate Profile https://www.researchgate.net/profile/Meredith-Anderson-9