Scientists probe new ways of controlling possums

A possum poison which will kill through catastrophic water loss to the gut could be developed in New Zealand.

AgResearch scientists, in collaboration with the University of Otago, have found unique aspects to possum gut physiology which could be used to develop new weapons against the pest.

But it will probably be about two years before the feasibility of the new concept is confirmed, AgResearch announced on its website.

In studies originally aimed at identifying possible routes for delivering oral toxins, scientists found some fundamental differences in physiology of the possum intestine, including those that control water balance which is essential for survival.

One possibility the team was looking at was targeting secretion - which moves water from inside the body into the intestine.

The research group found that several transport mechanisms across possum gut tissue differed widely from those in all other animals studied.

This offered potential as a new mechanism for possum-specific toxins not affecting other feral animals and birds, or dogs, livestock and humans.

AgResearch Invermay scientist Bernie McLeod said the potential bait would trigger secretion of water into the intestine causing catastrophic water loss into the gut and a quick death.

The advantage was that such toxins would have no effect on other animals, because the target mechanism would exist only in marsupials.

The first step in developing possum-specific toxins was to identify some aspect of physiology in possums that was different from that in other animals, then to find a toxin that acted on that possum-specific mechanism.

Dr McLeod, in collaboration with Dr Grant Butt, of the Otago University's Physiology Department, is investigating some basic life processes in possums with the aim of developing such toxins.

Possums belong to the marsupial family and although possum biology and possum ecology have been studied in depth, little is known of their physiological processes.

What the AgResearch group has identified is that their gut physiology appears to be different from other mammals.

AgResearch is working with the University of Otago to build up an understanding of physiology and transport function in the possum gut, using possums in AgResearch Invermay's possum colony, and molecular biology facilities at Otago University.

Dr McLeod emphasised that the development of possum-specific toxins would not mean the end of possums in New Zealand, nor would it replace existing possum toxins which would continue to play a major role in possum control.

- NZPA