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IPM Lessons From the Quest to Contain New Zealand’s Worst Vertebrate Pest

brushtail possum (Trichosurus vulpecula)

Brushtail possums (Trichosurus vulpecula) were introduced in 1858 in New Zealand to initiate a fur industry. A century later, however, they came to be viewed as a pest, and today they are deemed as the country’s major pest species, covering an estimated 90 percent of New Zealand. A new case study in the Journal of Integrated Pest Management examines management of the brushtail possum and the IPM lessons to be learned from those efforts. (Photo by iNaturalist user pfaucher, CC BY-NC 4.0)

By Ravneel Chand and Belinda Cridge, Ph.D.

Editor’s Note: Here at Entomology Today, integrated pest management is a vital subject, though one usually examined through its application to insect and arthropod pests. But IPM is a framework for management of all kinds of pests, and the Entomological Society of America’s Journal of Integrated Pest Management welcomes research from beyond the confines of entomology. Today we share a look at a new case study in JIPM on brushtail possums, a major pest in New Zealand, and state of IPM approaches toward it.

Ravneel Chand

Ravneel Chand

Brushtail possums (Trichosurus vulpecula) were liberated in 1858 in New Zealand to initiate a fur industry. Historical accounts detail the factors that led to widespread dispersal of possums. However, the view on possums as pest gained ascendancy in 1946 owing to a dramatic and deleterious impact on the native flora and fauna. Today, possums are deemed as the country’s major pest species, covering an estimated 90 percent of New Zealand.

Success in management has been achieved on a small scale, but the transition to whole country management poses new issues. At present, sodium fluoroacetate (1080) poison is the only feasible option for widespread control operations in New Zealand. The exaggerated use of 1080 poison in the 1980s caused an outcry of public opinion that continues to influence policy 30 years later. The ongoing disputes, which stem largely from historical mistakes and lack of public communication, suggests that increased use of this agent will not be tolerated.

Belinda Cridge, Ph.D.

Belinda Cridge, Ph.D.

Understanding the controversy is vital if new strategies are to be deployed to achieve large-scale pest management. Surely, this calls for caution when adopting new technologies, far more caution than would seem immediately reasonable.

Therefore, within the scope of the review titled “Upscaling Pest Management From Parks to countries: A New Zealand Case Study,” published this month in the Journal of Integrated Pest Management, we provide an overview of recent possum management strategies in New Zealand. Special attention is paid to the “Predator Free 2050” framework to summarize current practices and scrutinize new technologies in the absence of a “silver bullet.”

New Zealand’s Predator Free vision is a major national goal, announced by the government in 2017, to eradicate the country’s worst predators by 2050—often portrayed as a moon-shot to achieve a breakthrough science solution. This local challenge mirrors international issues and provides an opportunity to succinctly review the current state of play in New Zealand as a case study. Knowledge on what has worked previously and what might work alongside other techniques is a fundamental feature of the Predator Free 2050 plan that has immense relevance beyond one island nation.

While some lines of research in integrated pest management are showing potential, others demand further knowledge on the development and operation. Even advances over the past several years in the biological technology have expanded our theoretical approaches and delivered proof of concept. However, the technology remains practically challenged because of limited knowledge, ethical acceptability, and cost.

Overall, pest management in New Zealand has become increasingly sophisticated, with significant improvements achieved over the past 20-plus years through increased understanding of the risks, strengths, and constraints of using poisons, traps, and other eradication approaches. The information presented in this review suggests that widespread, country-wide control will require new tools. Ongoing action is required to improve the best practices from older approaches and to develop new tools that meet modern requirements: tools that are specific, competent, and efficient for possums.

Journal of Integrated Pest ManagementRead More

Upscaling Pest Management From Parks to Countries: A New Zealand Case Study

Journal of Integrated Pest Management

Ravneel Chand is currently pursuing a Ph.D. in toxicology at the University of Otago, New Zealand. His research focuses on characterising detoxification enzymes in New Zealand possums to increase the specificity of existing poisons and biocontrol agents via enzyme inhibition. Email:

Belinda Cridge, Ph.D., is a mechanistic toxicologist currently working as a lecturer and programme director within the Department of Pharmacology and Toxicology at the University of Otago. She loves nature and would like to wake each day to the calls of native birds. Email:


  1. It’s not a viable option for the large scale and inaccessible areas. In past, the government introduced the ‘bounty scheme’ where public were paid for the kill but overall the scheme failed due to a number of reasons.

  2. It’s a myth repeated by pro-poison propaganda that these places are ‘inaccessible’ and ‘remote’. One example nearby is a small block on a cycle trail, with residential areas within a 3km radius. This poison is a chemical endocrine disrupter: there have been NO epidemiological studies on any species.

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