6.2 Biotechnology for possum control
Research involving biotechnology is being used to develop new methods of possum control that will complement existing control methods. This research is accorded a high priority by the National Science Strategy Committee for the Control of Possums and Bovine Tb. Two approaches are being pursued at present.
Differences in physiology (life processes) between possums and other animals are being exploited in attempts to develop possum-specific toxins. These could ultimately reduce the use of non-specific toxins, and hence reduce risks to non-target species. For example, possums have a unique mechanism for maintaining their water and salt balance (an essential life process), so it may be possible to target this process to kill possums but not other species. Research on possum-specific toxins has only recently begun, and such compounds are unlikely to be available before 2007.
Methods of interfering with possum fertility are also being actively researched. Fertility control would suppress the recovery of possum numbers after conventional control, and offers potential advantages of humaneness, specificity and a reduction in the use of toxins. Two approaches are being investigated. One aims to block production of the hormones essential for breeding (and does not involve genetic modification). The other uses genetic modification technologies to stop breeding, by stimulating the possum's own immune system to interfere with reproduction during the stages of egg-to-embryo development. Research on delivery of fertility control is exploring both bait-delivered systems (which may not contain living, genetically modified material) and the use of a genetically modified possum-specific parasite, which would transmit naturally from possum to possum.
Significant technical problems and regulatory issues remain to be overcome in each approach. Bait-delivered products may be available by 2006-2008, with transmissible systems, if approved, available by 2010-2012.
The use of bio-controls is, understandably, the subject of considerable public debate. Surveys of public attitudes have clearly shown support for fertility control for possum management, but people are more cautious when delivery involves the use of genetic modification. A recent report by the PCE "Caught in the Headlights: New Zealanders' Reflections on Possums, Control Options and Genetic Engineering"52 canvasses the range of views of New Zealanders on this issue.
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