Recent research has shown that genes linked to metabolism in fruit flies are becoming more active, indicating a shift in their biological processes. This heightened gene activity is associated with a noticeable reduction in body fat and protein reserves, a trade-off that appears to enhance the flies’ resistance to mite infestations. The findings suggest that increased lipolysis, the breakdown of fats, and proteolysis, the breakdown of proteins, are prevalent in the mite-resistant strains of the insects.
Parasite paranoia
The depletion of essential nutrients may jeopardize the survival of fruit flies, even in the absence of mite predation. Nonetheless, the determination exhibited by these flies to remain active throughout the night indicates that the threat posed by mites is more significant. In fact, the mite-resistant flies exhibited heightened activity and oxygen consumption during nighttime hours, which matched the daytime levels of the control group flies.
In order to keep mites at bay, flies engage in constant movement, allowing them to evade any approaching parasites. To further explore this behavior, researcher Benoit conducted experiments to restrict the movement of resistant flies. The findings were stark: when movement was limited, these once-resistant flies became just as vulnerable to mites as their non-resistant counterparts. This highlights the crucial role of physical activity in defending against mite attacks.
As ectoparasites, mites pose a substantial threat to potential hosts such as fruit flies, which may benefit from heightened alertness. For hosts confronted by internal parasites, sleep often serves to bolster immune responses. However, for fruit flies facing external threats like mites, the act of sleeping could turn them into easy targets. The necessity of maintaining vigilance, aided by their stereoscopic vision, leaves little opportunity for rest.
The researchers noted, “The pattern of reduced sleep likely allows the flies to be more responsive during encounters with mites during the night,” in a study published in Biological Timing and Sleep. They added that while there may be variations in sleep patterns during the day, these differences are likely less significant since D. melanogaster typically sleeps less in daylight hours.
Fruit flies are not unique in experiencing disrupted sleep patterns due to parasitic threats; similar shifts have been documented in birds and bats when faced with nighttime risks of parasitism. For fruit flies, the downside of fatigue can be counterbalanced by enhanced fertility, making the pursuit of a mate worth the price of sleepless nights.
Biological Timing and Sleep, 2025. DOI: 10.1038/s44323-025-00031-7
