Investigation of Rodenticide Pathways Using Isotopically Labeled Bait
This project, funded by the Structural Pest Control Board, explored the use of isotopically labeled rodenticides to track anticoagulant exposure through food chains in urban environments. A novel isotopically labeled compound, C13DFN, was developed and incorporated into bait to monitor its movement from primary consumers (rats) to secondary consumers (coyotes). The study had four phases: bait design, rat labeling, coyote exposure trials, and a pilot field study.
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In laboratory trials, rats consumed varying amounts of C13DFN bait, which was later fed to coyotes under controlled single, intermittent, and daily exposure scenarios. Researchers monitored fecal and hair samples for rodenticide residues. The field study, conducted over 10 months, utilized bait stations in a 100-acre area to assess real-world exposure. Results confirmed the presence of C13DFN in rat and coyote feces, demonstrating how legally applied rodenticides travel through food chains. Residues were detected up to 14 days post-application and as far as 900 meters from bait stations.
This groundbreaking project underscores the role of rats as key vectors in rodenticide exposure and highlights the importance of informed mitigation strategies. Despite challenges, including ethical approvals and field logistics, the study achieved its goal of establishing tools to trace rodenticide pathways and assess their ecological impact.