New York, Sep 17 (IANS): Researchers have found that rats can be baited to or repelled from locations using pheromones found in the scents of other rats.

Rats cost the world's economy more than $300 billion a year. In addition to causing fines and business closures, rats spread disease, start fires and disable motor vehicles.

For the study published in The Journal of Urban Ecology, over a one year period researchers trapped and implanted microchips in city rats in a waste recycling centre in Brooklyn, New York.

"If we can pinpoint the scents and contexts that are most useful, then we increase our chances of creating novel control tools, but further research is needed under a broad range of conditions," said study researchers from Fordham University, Columbia University and Arrow Exterminators Inc.

To overcome issues in using GPS to track movement in dense urban environments, they utilised radio-frequency identification sensors.

Male and female scents were then placed on, or near, these sensors and replaced every two weeks.

To determine whether risk impacted the findings, the research team positioned these devices in sheltered, safe areas that rats were familiar with and also in more risky, open environments where rats were vulnerable to predation.

According to the study, rats reacted differently to male and female scents.

In general, when rats responded to sensors with male scents, risk was unimportant. Rats briefly visited male scents equally in exposed and sheltered areas, and then stayed away.

Female scents, however, were visited significantly more often than male scents (0.2 visits/day compared to 5.02 visits/day).

This implies that attractants may be more useful near sheltered areas while deterrent scents may be more useful in exposed areas where animals are vulnerable to predators.

These findings address a knowledge gap about rat scent preference that could assist in urban wildlife management tools, such as the deployment of baits or immuno-contraceptives.