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Efficacy of encapsulated sodium nitrite as a new tool for feral pig management


Worldwide feral pigs threaten native biodiversity, agricultural production and pose a risk to biosecurity as potential disease vectors. In New Zealand, the management of feral pigs has long been restricted to hunting, trapping, fencing and limited poisoning with 1080, warfarin and phosphorus. Sodium nitrite (NaNO2) is commonly used at very low concentrations in the food industry. At high doses, NaNO2 induces methaemoglobinaemia in mammals restricting the transport of oxygen by the red blood cell and in toxic doses leads to central nervous system anoxia, lethargy and death. Pen and field trials with pigs have been undertaken with an encapsulated formulation of NaNO2, designed to overcome the bitter taste of NaNO2 and mixed into a palatable paste bait. In pen trials, eight out of nine pigs consumed a lethal dose of paste bait. The average time to death was 59.5 min (±23.96 SD); symptoms lasted an average of 42.13 min (±19.12 SD) and included pale extremities, lethargy and ataxia. In a field trial, 12 radio-collared feral pigs were baited with the toxic paste bait formulation in prototype bait stations, where 11 of the 12 pigs consumed a lethal dose. Encapsulated NaNO2 has potential as an additional tool for the management of feral pigs, particularly when shooting and hunting is not practical or possible. Data in these studies were used to register this bait as a vertebrate toxic agent for feral pig management in New Zealand. This represents the first known registration of NaNO2 worldwide for use as a vertebrate toxic agent.

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Pen and field trials were carried out with approval from the Environmental Protection Agency (HSC000344), Agricultural Compounds and Veterinary Medicines Group (V009545). All applicable international, national and institutional guidelines for the care and use of animals were followed. All animal manipulations were approved by the Lincoln University Animal Ethics Committee (#233) and the Biosecurity Queensland Animal Ethics Committee (#CA 2010/05/438). The authors acknowledge the funding support of TBfree New Zealand (R-80701), the Department of Conservation, and the Ministry of Business, Innovation and Employment (LINX1003), Regional Councils in New Zealand and Connovation Ltd. Thanks also to Dr Steven Lapidge and Dr Simon Humphrys from the Invasive Animal Cooperative Research Centre and Linton Staples from ACTA for their encouragement and complimentary research in Australia, and Dr Peter Savarie and colleagues at the National Wildlife Research Center in the USA for their original work on methaemoglobinaemia inducers. Matthew Gentle and James Speed from Biosecurity Queensland for their all help running trials at the Robert Wicks Research Facility. Justin Foster, Donnie Frels and Bjorn Palm from Texas Parks and Wildlife Department for their continued work in pen trialling encapsulated NaNO2.

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Correspondence to Lee Shapiro.

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Communicated by J. Jacob.

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Shapiro, L., Eason, C., Bunt, C. et al. Efficacy of encapsulated sodium nitrite as a new tool for feral pig management. J Pest Sci 89, 489–495 (2016).

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  • Sodium nitrite
  • NaNO2
  • Vertebrate pesticide
  • Feral pigs
  • Methaemoglobinaemia