Minor genetic change creates unattractive female moths
Sex pheromones are used across the insect world. They are chemical compounds that are released by an organism to attract potential mates. For moths sex pheromones are incredibly important for recognising a mate and they are completely reliant upon scents rather than visuals when attracting a mate. However, there is still little known about the genes underlying the sex pheromone variation. This is information that is crucial when understanding how sexual communication works.
“We aimed to identify the genetic basis of sex pheromone variation in a moth species that shows large variation within populations,” explained the lead author Prof. Astrid Groot from the UVA Institute for Biodiversity and Ecosystem Dynamics (IBED). “We first selected the moths that produced extreme pheromone blends, followed by crossing and backcrossing the moth individuals. What we found was a single point mutation, a minor genetic change that resulted in the change of one specific enzyme that shifted the female sex pheromone from having a low ratio to an extremely high ratio of specific sex pheromone components, which rendered females completely unattractive.”
Most genetic studies have found that multiple mutations with interacting effects affect pheromone blends and other sexual signals, which tells us that evolutionary changes happen over the course of a long time in small steps. Therefore, it is surprising that the study carried out found that a single mutation which affected the biosynthesis of the moths sex pheromone quite dramatically.
Another interesting discovery was found by the research team, they found that same mutation in male moths did not affect their behaviour at all. Female moth’s signals shift to being unattractive whereas males with the mutation respond in the same way as males without the mutation, so both are attracted to the attractive blend.