Rabbit calicivirus disease as a possible biocontrol for rabbits
The rabbit problem
Currently, European feral rabbits (oryctolagus cuniculus) can be found over a little more than half (150,000 square km) of New Zealand’s total land area. They are usually absent from native forests, dense scrub lands, mature exotic forests, and from tussock grassland and scrub above 900 metres. About 11,700 square km of land is classified in the "extreme" and "high" rabbit-prone classes. About 300 square km in the South Island are considered to represent an "intractable" problem, due largely to the ineffectiveness of poisoning. This reflects the reluctance of rabbits to eat new foods (neophobia) and/or poison shyness, resulting from their previous experience of poison.
Rabbits degrade the land mainly by eating the vegetation that is critical in maintaining soil stability. Besides the direct degradation effects, they provide a food source for predators, largely ferrets and cats, which prey on native fauna. Ferrets are also prone to bovine tuberculosis, and are thought to be vectors of the disease.
The total annual cost of rabbits to the New Zealand economy is estimated to be at least $23 million, consisting of:
- at least $15 million for the direct costs of rabbit control (including $7.8 million from landowners, $5.7 million from ratepayers, and $0.45 million from the Department of Conservation); and
- an estimated $8 million of lost production due to rabbit grazing.
At present, rabbit numbers are controlled largely through the use of poisoned baits, most of which are spread by air. However, poisoning is expensive and is losing its effectiveness. New means of control are needed to complement those currently available.
A biological control method which is humane, rabbit-specific, highly contagious, not reliant on vectors, and results in a high mortality rate would offer hope of cost-effective control. As early reports on rabbit calicivirus disease RCD) suggested that it meets these criteria, research has been undertaken to evaluate its potential.
Contact for Enquiries
Manager, Strategic Science Team
MAF Biosecurity New Zealand
PO Box 2526
Wellington
NEW ZEALAND
Phone: +64 4 894 0115
Fax: +64 4 894 0731
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