Why being hungry affects flies’ mating

Female fruit flies mate more frequently when there’s plenty of food available and research published today in Proceedings of the Royal Society B reveals why.  Although it has been known for some time that feasting fruit flies have a higher mating rate, up to now nobody knew why the level of food available should influence the flies’ sex drive.

Now, a research team based at University College London’s Institute of Healthy Ageing has discovered that the key lies in the effect of fly nutrition on a well-known pathway involving insulin (IIS) which enables flies to sense the amount of food available to them.  The pathway is already known to affect a number of critical functions, including development, metabolism and stress control, but this study represents the first time that IIS has been shown to affect mating frequency.

The researchers found that by knocking out the genes responsible for regulating the insulin pathway, they reliably produced flies who mated less frequently.  ‘These fruit flies “think” they are hungry even though there might be plenty of food available’ explains Dr Stuart Wigby of the Edward Grey Institute at the Department of Zoology, University of Oxford, and lead author of the study.

While one might think that the frequency with which a female fruit fly chooses to mate is her own business, the research could have wide-ranging implications.  The insulin pathway that was studied is highly evolutionarily conserved, meaning that it can be found in many different organisms at different locations in the tree of life.  As such, the research could well have implications for other organisms, perhaps even mammals.  As the authors conclude, “the regulation of mating behaviour via IIS could be common among animals”.