The mysteries of sexual attraction just became a little less mysterious--at least for moths. A team of six American and European research groups, including one at Tufts University, has discovered which gene expressed in the brain of the male European corn borer moth controls his preference for the sex pheromone produced by females. This complements a previous study on the gene expressed in the female pheromone gland that dictates the type of blend she emits to attract males. The results of the new study were reported online on May 14, 2021 in Nature Communications. The article is titled “bric à brac Controls Sex Pheromone Choice by Male European Corn Borer Moths.” The implications go beyond making a better dating app for bugs. Now scientists can begin to ask why mating signals and mating preferences change in the first place, which is a long-standing paradox because any change could reduce the ability of an organism to successfully mate. Knowledge of these two genes will provide a better understanding of how the pheromones of the 160,000 moth species have evolved. Of course, one important role for mating preferences is to make sure you are not matching up with a completely different species. The signal sent by females must be preferred by males of the same species to ensure that like mates with like--a mechanism called assortative mating. The European corn borer is interesting because there are two types, called E and Z, with assortative mating within each type. Even though the two types can be mated to each other in captivity, E mostly mates with E, and Z with Z in the field. For this reason, the European corn borer has been used as a model for how one species can split into two, ever since the two pheromone types were first discovered 50 years ago. "That means we now know--at the molecular level--how chemical matchmaking aids in the formation of new species. Similar genetic changes to pheromone preference could help explain how tens of thousands of other moth species remain separate," said Erik Dopman, PhD, Professor of Biology in the School of Arts and Sciences at Tufts and corresponding author of the study.