Biologists at Lund University in Sweden are now able to show that the receptors enabling the primitive moth species, Eriocrania semipurpurella, find an individual of the opposite sex, probably evolved from receptors which help the moth perceive the fragrances of plants.

"Love is in the air" is a known expression. And it's true, at least for moths. The female emits sex pheromones into the air to attract a male with which she can mate. The male senses the female's pheromones with the help of receptors located in his antennae. How the males developed the ability to pick up on these sex pheromones, however, has been unclear until now.

Researchers at the Department of Biology in Lund have now drawn the conclusion that plant odourant receptors evolutionarily preceded sex pheromone receptors in primitive species of moths. The researchers studied the leaf miner moth, Eriocrania semipurpurella, and found that this primitive species was likely able to find its host plant, birch, with the help of plant odourant receptors located on its antennae. Subsequently, the receptors of this species evolved a novel function to sense the sex pheromones of a moth of the opposite sex.

The results are important to increase our understanding of sex pheromone communication. Although it is basic research, the results may become practically applicable in the future.

"More research on the receptors could potentially lead to more successful ways to fight insect pests, for example, blocking the sex pheromone receptors may prevent the males from finding the females," says Martin N Andersson, biologist at the Faculty of Science in Lund, and one of the researchers behind the study.

Among the moths, there are four main groups of pheromones. The classification is based on the chemical composition and production routes of the female. Eriocrania semipurpurella uses a type 0 pheromone -- a type which, in its structure, resembles many odourants of plants. The researchers have now identified the receptors for this type of pheromone in Eriocrania semipurpurella. Next, they showed that these receptors can also sense plant odourants, and that the receptors are evolutionarily related to plant odourant receptors in other species. Based on this, the researchers conclude that the pheromone receptors of this primitive species evolved from plant odourant receptors.

According to the researchers, it is not impossible that a similar scenario also occurred in moths more advanced than Eriocrania semipurpurella.

"Research on more species is necessary, but evolution may very well have taken the same path in an ancestor of more advanced Lepidoptera," says Martin N Andersson.