How Cockroaches Lost Their Sweet Tooth—Fast

We're not so lucky as to have a genetic mutation that keeps us away from sugar—but that's the case with some cockroaches, which scientists reveal have quickly evolved in a way that keeps them away from glucose, a popular ingredient in roach-poison bait. That cockroaches have grown resistant to a poison would be relatively unremarkable, reports the New York Times; what makes this a "fantastic discovery," in the words of an entomologist not involved in the study, is that the bugs developed an aversion to any bait with glucose in it. The behavior was first spotted in Florida in the 1980s, reports the AP, which marvels that the trait became widespread in as few as five years, or 25 generations of cockroaches; and it's finally been explained by a trio of US researchers.

They studied German cockroaches, and found that roaches had evolved such that when their taste hairs encounter the sweet glucose, nerve cells register a bitter taste instead, repelling them. (Interestingly, AP notes that the studied cockroaches actually ate most kinds of bait they were presented with, indicating that manufacturers have tweaked their recipes, which are a trade secret.) The research, published in Science, may help explain the behavior of other pests, like malaria-spreading mosquitoes, which have evolved to no longer "rest on walls that are treated with insecticide," says one of the scientists; he speculates that his cockroach research could serve as a tool in discovering why. (More cockroaches stories.)