A wee trick for getting rid of rats

Developing new weapons to control the deadliest predator of New Zealand native birds is the goal of a research project underway at Victoria University.

Researchers from five different disciplines at Victoria are collaborating to pinpoint the make-

up of rodent urine and use the knowledge to create bait that will more effectively attract rats.

The work is led by Dr Wayne Linklater from Victoria's School of Biological Sciences, and involves researchers with expertise in chemistry, ecology, molecular biology and statistics.

Ultimately, the team hopes to be able to produce a long-lasting substance that will lure rats into traps, allowing the Department of Conservation to accurately gauge numbers in a given area and put appropriate control programmes in place.

One of the team, chemist Dr Rob Keyzers, is helping to analyse what's in the urine of mice and rats.

Currently, much more is known about mice which excrete relatively large amounts of a distinctive protein in their urine. Dr Keyzers says this Major Urinary Protein, or MUP, is an ideal agent to hold and slowly release pheromones which attract other mice.

"Male rat urine has something similar to the MUP but the pheromones released are different. My work is focused on understanding the unique pheromone compounds in rat urine so we can use them, or a laboratory-created equivalent, in traps."

Dr Keyzers says the beauty of the system is that, as well as using a proven attraction agent like pheromones, the rodent protein releases aromas slowly so traps using them will remain active for a long time.

In addition to analysing rat urine, the researchers are running "choice trials" with rodents to confirm which are the attractive pheromones in rat urine.

Dr Keyzers says if the research is successful the benefits will be two-pronged.

"We want to come up with a better rodent trap but we also want to give DOC the means to carry out population tests, which is where Professor Shirley Pledger, our statistical researcher, comes in.

"If we can design a device that reliably attracts rats and also tags them with some kind of mark before they exit, we'll be able to get a more accurate sample of exactly how many rats are in the immediate vicinity and then use statistical modelling to assess the wider population."

The research has funding from Viclink, Victoria University's commercialisation company, and the Department of Conservation.

Dr Keyzers says the only downside of the research project is the "reek" of rodent urine.

"The amounts they excrete are tiny but it has a really foul odour."

A focus of Dr Keyzers previous research is understanding the volatile, sulphur-containing molecules that give wine its flavour and aroma.

It may seem a far cry from profiling rodent urine but Dr Keyzers says both areas of research are about identifying and analysing naturally occurring molecules and using them to achieve a desired outcome. With wine, he says, that means ultimately being able to design flavour and aroma profiles to target the palates of consumers in specific export markets.