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Thumbs up for possum fertility control

NEWS RELEASE - June 12, 2001

Thumbs up for possum fertility control

A nationwide survey by Landcare Research has shown that overall, the public approves of the development of a fertility control for one of New Zealand's worst pests - the possum. The survey also shows that men are more enthusiastic about possum control in general than women.

Possums damage native forests, spread bovine Tb among cattle and deer, and eat the eggs and chicks of native birds. Their numbers have been climbing despite attempts over several decades to curtail this through poisoning, trapping and shooting.

Landcare Research has compiled the results of its telephone survey of 1000 people in March and April. The survey aimed to find out people's views on possums, the current control methods, and two potential fertility control methods which may include the use of genetic modification (GM), which are being researched at various institutes. One involves a bait containing a protein from possum eggs, which makes the female possum react against its own eggs, and become less fertile. The other involves curtailing possums' sex drive, through a bait that works on the brain to inhibit the production of breeding hormones.

The survey shows that the vast majority of respondents (96%) believe that possums are a problem, and that fertility control is highly acceptable (rated acceptable by more than 70% of respondents). Fertility control is evidently much more acceptable to the public than the most common methods of possum control: leg-hold traps (29%) and 1080 poisoning (31%).

But getting fertility controls to the possums usually requires the use of an organism which has been genetically modified to carry the fertility control. The public were asked to rate the acceptability of four delivery methods, namely, a GM plant (killed so it can't spread, and presented in a bait); a GM bacterium (killed, in a bait); a live GM virus spread from possum to possum; and a live GM parasite worm spread from possum to possum. There was considerable polarisation, with each rated acceptable by at least 30 percent and unacceptable by at least 30%. But people clearly dreaded the idea of viruses, with far more people rating them unacceptable than acceptable. The GM plant method was acceptable to more people (43%) than any of the other methods.

"All the control methods and all the delivery methods are more acceptable to males than females" says Landcare Research social scientist, Roger Wilkinson. "The difference is highly significant statistically. No other break-up of the respondents, such as urban versus rural for example, showed the same degree of difference.

"The differences in opinion between men and women are most pronounced with regard to poisoning. In our survey, 40% of men said 1080 poison was an acceptable means of possum control, compared with just 22% of women".

Where to from here?

Landcare Research has undertaken not to pursue any research avenues the public says it clearly does not want. Development manager Ian Whitehouse says the survey provides support for the approach that Landcare Research is adopting - interfering with fertility, delivered through a GM plant bait.

"We have rejected the use of viruses because people are clearly against that.

"Our earlier focus groups suggested to us that using dead GM bacteria to deliver a possum fertility control would be more acceptable to the public than this survey shows. This is because the GM bacteria would be killed before it left the laboratory so it could not grow or spread in the field" Mr Whitehouse says.

" We will continue with our laboratory research on dead GM bacteria as another potential way to get fertility controls to the possums. It may be that as more people become comfortable with the idea of insulin produced with GM bacteria, they will become more accepting of dead GM bacteria for possum control.

"In about two years time, we will hold a similar survey to this one, to see if attitudes have changed. If our research goes to plan, and ERMA and the public approve, a preliminary, limited field trial of the GM carrot bait would take place in about three years time".

Mr Whitehouse says one of the first questions people ask is why, if you can get a possum to eat a bait, you do not just kill it. "The answer is that poisons are good at getting possum numbers down, but fertility control used in conjunction with poisons should mean that poisoning would only need to be done about a third as often as it is at the moment.

" This would lessen the use of 1080, and reduce associated environmental impacts and risks to non-target species".


For more information, or for a copy of the preliminary report, contact:

Roger Wilkinson Sociologist Landcare Research Lincoln wk:(03) 325 6701 x3818 mobile: 025 501 183

Ian Whitehouse Development Manager Landcare Research Lincoln wk: (03) 325 6701 x3764 mobile: 025 336 092

Diana Leufkens Media Liaison Landcare Research Lincoln (03) 325 6701 x3858 025 277 6183

Landcare Research

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