"Perfume" Lures Flies Into Trap

Flies are attracted to decaying and fermenting substances but using such substances in flytraps is not practical because they dry out too fast and require a lot of maintenance. Synthetic combinations of odours which flies find attractive would seem to be a more effective solution. In order to determine what substances are attractive to flies, the biologists at University of Groningen investigated how flies smell.

Flies smell with special cells in olfactory hairs on their antennae and palps. When olfactory molecules bind to the olfactory cell, tiny electrical impulses are transmitted to the brain. An electrode placed at the base of the hair can measure these impulses and thus determine the reaction to an olfactory stimulus. The STW study showed that the majority of olfactory cells react to a variety of smells and that there are only a few specialised olfactory cells that distinguish one specific smell.

The researchers measured a strong reaction for example, when the fly was stimulated with 1-octen-3-ol, a substance present in meat, and 3-methylphenol, which is found in chicken manure. For the fly, these substances are like an attractive perfume. However, flies are also sensitive to less predictable odours.

Because flytraps need to work effectively in areas with complex combinations of smells, such as stables, the researchers carried out tests in the presence of background smells. It was found that the flies were not much distracted by the background smell. This means that it may well be perfectly possible to use attractants or repellents effectively in areas where there is already a strong smell.

The researchers concluded that using the proposed attractive mixtures in traps can indeed help to control a whole population of house flies. The mixtures work on flies whether they are young or old, male or female, small or large. They also work in both clean areas and areas where there is already a strong smell. Future behavioural tests will determine whether the synthetic mixtures can in fact be used as attractants in flytraps.