Possum Research

September 2008
AgResearch, the University of Otago, also Victoria, and also Landcare Research have all been involved in possum research. All of these possum projects have been brought together into a virtual centre called the National Research Centre for Possum Biocontrol. It functions like an umbrella for the researchers who have all been working together since July 2005. Next June 2009 is a big target, a milestone for research they have to meet.

1. Possum specific toxins

This is a promising research project with a very good chance of success, and it is running with the University of Otago. Dr Grant Butt from the Physiology Department of the University is seeking to develop new toxins to kill possums along with Dr Bernie McLeod from AgResearch. Grant has extensive research background in epithelial cell physiology, which is the basis of this work.

This work is aimed to kill possums only; there is no effect on farm animals or companion animals. Thats because the way the toxin would work is very specific to possums or to marsupials.

130 million years ago marsupials diverged from other animals, which is plenty of time for them to develop different mechanisms. For example in the intestine possums have a different way of secreting water compared with other animals. The scientists have been studying the way possums do this, to target this mechanism with possum specific toxins.

The scientists have a target to get to some major milestones by next June with the toxin project, so they are trying to compress three years of research into one.

2. Other Research Projects

These include work on possum reproduction, and a couple of strategies to make possums infertile. This work is also collaborative.

And heres some work to make men feel really uncomfortable: the scientists are using possums to model for diseases in humans: in this case prostrate glands. The prostrate gland in adult male humans often enlarges, and because they circle the urethra, can cause lots of problems for affected men (urodynamic consequences), which has to be resolved by surgery.

In possums, prostrate glands enlarge during the breeding season and regress during the non-breeding season and they can vary in size from 0.4g -107g. Possums can make their own prostrate glands smaller again. So the scientists are trying to identify the growth factors involved in making prostrates grow and regress.

4. The survival instincts of possums

Bernie says we certainly have to give possums a great deal of respect. They are absolute survivors, he says. After we trap possums, they are transferred in a sack, anaesthetized, checked over, ear-tagged, weighed and monitored to make sure they are thriving in the research facility.

They have set up a system of keeping possums in large groups in pens, where they are kept from the time they arrive.

One possum they caught had been shot through the shoulder blade, and its front leg had been shattered and its wound was a few weeks old. In its pouch was a week old young. The hunter told them four weeks previously he had winged a possum in the area that this possum was trapped. As pregnancy in possums is 17-18 days, this animal must have mated 10 days after it had been shot. Thats determination!

When you are working with them you have to give them some respect. If a possum manages to sink its feet into you, it wont let go until you let go. The other option is to prize its jaws open

Sometimes we get scratched, but when you learn what you can and cant do with possums you dont get bitten very often, says Bernie.

3. The current possum facilities.

There are two possum facilities at Invermay. The older facility can house about 150-180 possums. A lot of experiments based in this facility are short term, so the possums may not be staying long. For reproductive experiments, the possums can be in captivity for months if not years. A group of vasectomised possums were here for about seven years, and most of them weighed more than 5kg.

They get fed a specifically formulated cereal pellet which is very low in calcium, because possums are very susceptible to calcium blockages.

They have access to cereal bait pellets continuously, and fresh water. We put branches in their pens for them to browse on, and we feed them on fruit and vegetables.

A few months ago Wallaceville relocated here, and we have another facility recently completed which is designed to house 200 possums. The experiments in that facility will mostly be long term. Pet Possums.

Although it is illegal to keep possums as pets, this does happen. Sometimes pet possums come to us. We generally keep them in a pen by themselves. They are useful for showing groups of school kids.