Secondary poisoning risk for encapsulated sodium nitrite, a new tool for possum control

Brushtail possums (Trichosurus vulpecula) present an ongoing threat to New Zealand’s environment and economy. Research into additional control techniques is vital to ensure that a variety of efficient tools are available to help achieve population suppression. Encapsulated sodium nitrite (NaNO2) has been developed in New Zealand as a new toxin for possum and feral pig (Sus scrofa) control. Its toxic effects at high doses are mediated through the induction of methaemoglobinaemia, a condition in which the carrying capacity of oxygen in red blood cells is reduced.

Encapsulated sodium nitrite as a new toxicant for possum control in New Zealand

Sodium nitrite (NaNO2), a commonly used food preservative, has been researched in New Zealand for the control of brushtail possums (Trichosurus vulpecula). In sufficiently high doses, NaNO2 is toxic because it disrupts circulatory transport of oxygen. As NaNO2 is very bitter, encapsulation and mixing it through a highly palatable bait formulation is necessary to effectively deliver it to target pest species. In no-choice cage trials, 12/12 possums consumed a lethal dose of toxic paste bait and died on average after 95.6 minutes (±4.9 SE).