Blattella germanica (German cockroach) - Photo by Sarah Camp
Researchers at Queen Mary's School of Biological and Chemical Sciences at the University of London (London, UK) allowed a group of hungry German cockroaches (Blattella germanica) to choose between two piles of food. Instead of randomly choosing either pile, most of the cockroaches collectively fed on one pile. Furthermore, the more cockroaches there were on the pile, the longer each individual would stay to feed. The research team led by Dr. Mathieu Lihoreau inferred that cockroaches use a short-distance pheromone to communicate with one another once they are already at or near the food, unlike the longer-distance chemical trails used by ants. This 'foraging pheromone' has not yet been identified, but Lihoreau and his colleagues point at chemicals in the roach saliva or hydrocarbons in the cuticle that cover roaches' bodies as the possible pheromones. Ants' food trail pheromones are hydrocarbons.
Pheromones - chemicals secreted by an organism that can influence the behavior of others within the same species - can play a role in sex, warnings, foraging, and other important communication within a species. Female Blattella germanica, the German cockroach used in this study, have previously been shown to use a sex pheromone to attract mates. In America, we're familiar with a larger genus of roach, Periplaneta americana. A sexual pheromone has been identified in the the American roach as well, but potential foraging pheromones have not been researched because until now, it was generally accepted that roaches foraged alone.
|Periplaneta americana (American Cockroach) - Photo by Mike Keeling|
Fortunately, cockroaches' pheromone food recommendations can't travel long distances, summoning many colonies to our kitchens. Researchers have not yet discovered a roach internet system.
Note: In Massachusetts, landlords of buildings with two or more apartments are responsible for keeping their units roach-free [PDF].