fruit flies

Some flies go insomniac to ward off parasites

Biology, circadian rhythm, Drosophila, evolution, fruit flies, parasites, Science / Mike M. / May 2, 2025

Those genes associated with metabolism were upregulated, meaning they showed an increase in activity. An observed loss of body fat and protein reserves was evidently a trade-off for resistance to mites. This suggests there was increased lipolysis, or the breakdown of fats, and proteolysis, the breakdown of proteins, in resistant lines of flies.

Parasite paranoia

The depletion of nutrients could make fruit flies less likely to survive even without mites feeding off them, but their tenaciousness when it comes to staying up through the night suggests that being parasitized by mites is still the greater risk. Because mite-resistant flies did not sleep, their oxygen consumption and activity also increased during the night to levels no different from those of control group flies during the day.

Keeping mites away involves moving around so the fly can buzz off if mites crawl too close. Knowing this, Benoit wanted to see what would happen if the resistant flies’ movement was restricted. It was doom. When the flies were restrained, the mite-resistant flies were as susceptible to mites as the controls. Activity alone was important for resisting mites.

Since mites are ectoparasites, or external parasites (as opposed to internal parasites like tapeworms), potential hosts like flies can benefit from hypervigilance. Sleep is typically beneficial to a host invaded by an internal parasite because it increases the immune response. Unfortunately for the flies, sleeping would only make them an easy meal for mites. Keeping both stereoscopic eyes out for an external parasite means there is no time left for sleep.

“The pattern of reduced sleep likely allows the flies to be more responsive during encounters with mites during the night,” the researchers said in their study, which was recently published in Biological Timing and Sleep. “There could be differences in sleep occurring during the day, but these differences may be less important as D. melanogaster sleeps much less during the day.”

Fruit flies aren’t the only creatures with sleep patterns that parasites disrupt. Evidence of shifts in sleep and rest in birds and bats has been shown to happen when there is a risk of parasitism after dark. For the flies, exhaustion has the upside of better fertility if they manage to avoid bites, so a mate must be worth all those sleepless nights.

Biological Timing and Sleep, 2025. DOI: 10.1038/s44323-025-00031-7

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Male fruit flies drink more alcohol to get females to like them

Fruit flies (Drosophila melanogaster) are tremendously fond of fermented foodstuffs. Technically, it’s the yeast they crave, produced by yummy rotting fruit, but they can consume quite a lot of ethanol as a result of that fruity diet. Yes, fruit flies have ultra-fast metabolisms, the better to burn off the booze, but they can still get falling-down drunk—so much so, that randy inebriated male fruit flies have been known to court other males by mistake and fail to mate successfully.

Then again, apparently adding alcohol to their food increases the production of sex pheromones in male fruit flies, according to a new paper published in the journal Science Advances. That, in turn, makes them more attractive to the females of the species.

“We show a direct and positive effect of alcohol consumption on the mating success of male flies,” said co-author Ian Keesey of the University of Nebraska, Lincoln. “The effect is caused by the fact that alcohol, especially methanol, increases the production of sex pheromones. This in turn makes alcoholic males more attractive to females and ensures a higher mating success rate, whereas the success of drunken male humans with females is likely to be questionable.”

Fruit flies are the workhorses of modern genetics research, used to study everything from cancer to sleep disorders. They make excellent model systems because they share so many genes with humans, plus they are cheap, easy to breed, and can be genetically altered easily. Many years ago, I had the privilege of visiting the University of California, San Francisco laboratory of behavior geneticist Ulrike Heberlein, who spent years getting fruit flies drunk in an “Inebriometer” to learn about the various genes that influence alcohol tolerance. (Heberlein is now scientific program director and laboratory head at the Howard Hughes Medical Institute’s Janelia Farm Research Campus.)