Washington, Sept 12 : Just like humans, fruit flies too feel the influence of peers, according to two new studies in the September 11th issue of Current Biology, a Cell Press publication. he researchers found that group composition affects individual flies in several ways, including changes in gene activity and sexual behavior, all mediated by chemical communication.
"Many take for granted that communication among insects is hard-wired," said Joel Levine of the University of Toronto Mississauga.
"We have observed that communication may be influenced by relationships even in insects like fruit flies, which have not been traditionally considered to be social insects. We have seen individual responses that appear to be altered quickly--within a day of joining a group.
"This level of spontaneity or plasticity is complex because it occurs on many levels: involving neural and non-neural tissues, changes in gene expression and physiology, and changes in behavior, all of which are inter-related," Levine added.
That connection between an individual and its environment, both social and otherwise, reveals a depth that is often missing in experiments that focus exclusively on one or the other, he said.
In one study, the researchers reveal that specialized cells of the fly called oenocytes, which produce chemical signals known as pheromones, operate according to an internal circadian clock. However, the "ticking" of that clock varies depending upon the social environment the flies find themselves in: Males in mixed company-meaning in the company of other flies that were less similar at the genetic level-produced different chemical signals than did males in genetically uniform group, they found.
Those signals had a clear effect on behavior: flies in genetically more mixed social groups had more sex than those in more uniform groups did.
To further explore the connection between chemical communication amongst fruit flies and their physical and social environments, the researchers examined in a second study the chemical composition of pheromones produced by flies in mixed versus homogeneous groups.
Those tests were conducted in flies under conditions of constant darkness and in those under a normal light-dark cycle.
Their results showed important effects on flies of both the physical and social environment. Moreover, they found a strong interaction between the genetic background of individual flies and their social environments.
"The response of an individual male to others like him depends on his neighbors," Levine said.
"That response is quite specific because it affects some of the chemicals made by a fly, but not others," the researcher added.
The results suggest that chemical communications is a rather "fickle" trait, depending heavily on the influence of a fly's peers.