The tears of baby mice make adult female mice less interested in mating, meaning in theory they could be used as a form of pest control. A study carried out by scientists in Japan has revealed that pheromones produced by young mice override the sex stimulating chemicals produced by amorous males. This makes the males less desirable to females and could therefore be used to lower reproduction rates. Only mice aged one to three weeks produce the substance ESP22 which is spread liberally around their territory.
Its effects may benefit the young mice by stopping their mothers fornicating, leaving more food and attention for them. Scientists think this natural birth control, which has been tested and deemed effective on all female mice, could be an effective way of stopping mice spreading. “It is unlikely that other animals would be affected because pheromones are so species specific,” said Professor Kazushige Touhara from the University of Tokyo, who led the project. “The sex-rejecting behaviour is an innate instinct, so it’s also unlikely that the mice will learn to change their behaviour.”
A similar pheromone called ESP1 is produced by male mice to encourage sex and scientists have found that ESP22 signals replace these signals in female mice’s brains, stopping them breeding. Their findings were published in the journal Nature Communications, and as well as giving an insight into mouse brain activity, it hopefully will lead to a more practical purpose. “ESP22 is difficult to artificially synthesise, so we want to find a smaller portion of the pheromone molecule that could be added to mouse drinking water,” said Professor Touhara. “This could prevent mice breeding in areas where they are pests.”
The scientists not that pheromones are highly species specific and direct connections between human and mouse behaviour could not be made, in this case.