There are about 4,000 species of fruit flies in the world. The vast majority feed on fruit and many thrive indoors in our kitchens. But one species has puzzled scientists for many years. It differs markedly from its relatives in that it lives in flowing watercourses in Africa.
For example, the larvae have claws to hold on to the surface despite strong currents and feed on insects.
"I've been fascinated by it ever since I was a doctoral student and wanted to study it. It has truly changed the way of life, from rotting fruit to a predator in flowing water," says Marcus Stensmyr, associate professor at Lund University and researcher in zoology.
Mysterious variant
This particular fruit fly has been extremely elusive and has not been observed since 1981. Then Marcus Stensmyr and his research colleagues received a tip that there was a preserved specimen in a museum in Zurich, Switzerland.
Using modern technology, they have managed to extract DNA from the preserved flies and map their genome. The results, published in the scientific journal Current Biology, show that it belongs to a group of flies that live near rushing water in southern Asia. These "mysterious" water flies in both Asia and Africa have simply adapted to their environment and are genetically different from those we have in places like Sweden.
"The African variant had almost completely lost its sense of smell and has a completely different metabolism. It would not do at all in a Swedish kitchen," says Marcus Stensmyr.
Provides answers about climate
The research points to the value of collections of insects and animals. Using the same method, researchers can see how changes in the climate and environmental toxins have affected, for example, bees, butterflies and bumblebees in our vicinity.
Marcus Stensmyr has not given up hope of finding an aquatic fruit fly.
"Absolutely not. We have found places in Tanzania where we think it might be possible to see them."
Facts: Fruit flies
These flies are found everywhere in nature, so it is difficult to prevent them from entering houses and apartments.
If you have fruit flies at home, there are tricks to get rid of them.
Dispose of fruit waste in sealed bags and keep the fruit bowl free of overripe fruit.
Clean reusable bottles and similar items, and store them sealed in plastic bags, for example.
Don't leave dishes in the sink for too long and remove food residue from the sink immediately.
Throw away the trash every day and keep an eye on the compost.
Clean the sink and floor drain with a coarse brush and dish soap to get rid of eggs and larvae that may be present at the opening.
Source: Anticimex, SLU
