Biological control of possums – introduction
Possums are one of New Zealand's biggest pests. Currently they are controlled by poisoning and trapping, but this is expensive and ongoing. Biological control has the potential to provide novel ways to control possums, and combined with conventional control methods, may offer more sustainable solutions.
Possum
Possums are one of New Zealand's biggest pest species – eating native trees, birds and invertebrates, and destroying ecosystems.
Why possums are a problem
Possums are a pest in New Zealand. They eat the native trees, birds and invertebrates, and destroy ecosystems. They can also spread tuberculosis, which has a huge financial impact on the dairy and beef industries.
Current methods of control
Possums are currently controlled through trapping and poisoning (using mainly 1080). These methods are very costly and in the case of poisoning, not specific to possums.
What is biological control?
Biological control, or biocontrol, is the use of a living organism, or the product of a living organism, to control the numbers of another organism, usually a pest. Biocontrol can be defined in several ways, to find out more:
Biocontrol and the importance of species specificity
Of course it is really important that other species are not affected. This is one of the problems with using poisons, like 1080. They are often non-specific, and kill species other than possums, like dogs and deer.
An important part of the research being done at AgResearch into biocontrol of possums is that the biocontrol agent will only affect possums.
Biocontrol methods are:
sustainable, having ongoing, permanent effects
specific to the species being controlled.
Methods of biocontrol
Scientists in New Zealand explored several biocontrol methods for reducing possum numbers. These included using toxins or vaccines against possum fertility. Further information on these two examples are in the articles: Hormone-toxins to reduce possum fertility and Vaccines to reduce possum fertility.
There are a number of ways biocontrol agents, like toxins or vaccines, can be delivered to possums. We need to consider the advantages and disadvantages of each method of delivery before we decide which option to use. Find out more in the article, Delivering biocontrol agents to possums.
This article provides explanations of key terms and definitions in possum biocontrol.
Updates
In a 2011 report, Dr Jan Wright, Parliamentary Commissioner for the Environment, wrote that although significant research effort and resources were put into possum contraceptive vaccines and hormone toxins, funding for the projects finished in September 2010. There was concern about the length of time required to produce results, risks associated with the biocontrol agents and potential controversy over genetic engineering.
New Zealand's Biological Heritage National Science Challenge recognises the potential for gene drives and/or other GE technologies in the eradication of pests in New Zealand. Part of their remit was to explore the social and bioethical issues surrounding genetic engineering.
Related content
This article outlines some initiatives working to achieve New Zealand Government’s vision of becoming predator-free by 2050.
Can we make New Zealand pest-free? Be inspired by Zealandia’s overview and pest free resources.
Biocontrol was a potential answer to the controversy surrounding 1080. Read about 1080 in this introductory article.
Useful links
Read the full report on challenges for pest management in New Zealand on the Royal Society New Zealand website.
For an update on emerging issues in New Zealand pest management, including vertebrate pests listen to this RNZ programme from 2014.
Read about the findings from a study that collated the results of a number of individual studies relating to possum control and the links to biodiversity outcomes
