Entomologists at the The University of California, Riverside recently conducted an experiment to discover why flies are attracted to beer. The scientists say flies can sense glycerol, a sweet-tasting compound that yeasts make during fermentation.
Anupama Dahanukar, an assistant professor of entomology, whose lab conducted the research, says, "Insects use their taste system to glean important information about the quality and nutritive value of food sources. Sugars signal high nutritive value to flies, but little is known about which chemical cues flies use for food sources that are low in sugar content - such as beer."
Dahanukar's lab examined the feeding preference of the common fruit fly for beer and other products of yeast fermentation. The researchers found that a receptor (a protein that serves as a gatekeeper) that is associated with neurons located in the fly's mouth-parts is instrumental in signaling a good taste for beer. The name of this receptor is Gr64e. Once a fly has settled on beer, Gr64e detects glycerol and transmits this information to the fly's neurons, which then influences the fly's behavioral response.
Dahanukar says flies first rely on smell to locate a food source. The sense of taste does not come in play until the fly lands on the beer.
Dahanukar says, "Taste becomes important only after the fly makes physical contact with food. A fly first locates food sources using its odor receptors - crucial for its long-range attraction to food. Then, after landing on food, the fly uses its taste system to sample the food for suitability in terms of nutrition and toxicity."
The study was reported
in the journal, nature neuroscience
Photo: Dahanukar lab, UC Riverside