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Publication Open Access Encapsulated sodium nitrite as a new toxicant for possum control in New Zealand(New Zealand Ecological Society, 2016) Shapiro, L; Eason, CT; Bunt, Craig; Hix, S; Aylett, P; MacMorran, DSodium 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). In two-choice cage trials 7/8 possums consumed a lethal dose of toxic paste bait and died on average after 96.7 minutes (±11.4 SE). Two field trials targeting possums using this toxic paste in bait stations reduced their abundance by 81.2% (± 2.5% SE) and 72.7% (± 1.6% SE) respectively. NaNO₂ paste, known as BaitRite, has been registered in New Zealand as a vertebrate toxic agent for controlling possums.Publication Open Access Development of re-setting toxin delivery devices for stoats and ratsMurphy, E.; Sjoberg, Timothy; Dilks, P.; Barun, Arijana; Smith, D.; Aylett, P.; MacMorran, D.; Eason, CharlesRats and stoats continue to have a major impact on biodiversity in New Zealand, and improved control techniques are required to avoid further extinctions. A resetting toxin delivery device (Spitfire) is being developed as part of a programme entitled 'Pest Control for the 21st Century', funded by the Ministry of Business, Innovation and Employment. The Spitfire works by firing a paste containing a toxin on to the belly of stoats and rats as they pass through a tunnel. The device then resets. When the stoats and rats groom the paste from their fur, they ingest the toxin. Each Spitfire is capable of approximately 100 doses and is fitted with a counter and a delay mechanism. The first successful field trial of the stoat Spitfire was undertaken in the Blue Mountains, West Otago in late 2013. Stoat abundance was significantly reduced but technical problems meant the trigger mechanism had to be re-designed. Para-aminopropiophenone (PAPP), the toxin used for the stoat trial, is not lethal enough for rats, so 1080, Zinc phosphide, cholecalciferol, C+C (cholecalciferol + coumatetralyl) and sodium nitrite are being investigated as alternative toxins for the rat Spitfire. Field trials are planned for both stoats and rats using Spitfires in 2014/15.