The Drosophila microbiome has a limited influence on sleep, activity, and courtship behaviors

Abstract

In animals, commensal microbes modulate various physiological functions, including behavior. While microbiota exposure is required for normal behavior in mammals, it is not known how widely this dependency is present in other animal species. We proposed the hypothesis that the microbiome has a major influence on the behavior of the vinegar fly (Drosophila melanogaster), a major invertebrate model organism. Several assays were used to test the contribution of the microbiome on some well-characterized behaviors: defensive behavior, sleep, locomotion, and courtship in microbe-bearing, control flies and two generations of germ-free animals. None of the behaviors were largely influenced by the absence of a microbiome, and the small or moderate effects were not generalizable between replicates and/or generations. These results refute the hypothesis, indicating that the Drosophila microbiome does not have a major influence over several behaviors fundamental to the animal’s survival and reproduction. The impact of commensal microbes on animal behaviour may not be broadly conserved.

How commensal microbes shape the physiology of Drosophila melanogaster

“…Of note, many recent studies focus on the influence of commensal bacteria on adult fly behavior, such as locomotion [9,10], feeding [11,12], social interactions [10,13] and egg-laying [14]. These are important advances but will not be covered in this review.…”

A gut microbial factor modulates locomotor behaviour in Drosophila

“…However, further work is needed to identify the exact neurons and neuronal mechanisms involved, including potential changes in firing patterns. It would also be important to clarify the sex-specific aspects of these microbial effects on locomotion 30,46 . It is intriguing that germ-free mice display hyperactivity similar to axenic Drosophila , and specific bacteria have been shown to decrease locomotor activity in mice 1,47,48 , although the neuronal pathways implicated in mammalian systems have yet to be identified.…”

Sleep in Drosophila and Its Context

“…Microbiota also appear to interact with insulin signalling which is known to regulate feeding and sleep (Shin et al, 2011). While microbiome composition has been shown to affect mating choice (Sharon et al, 2010), egg laying, and feeding (Leitao-Goncalves et al, 2017), rather surprisingly, another study found that eliminating the microbiome in fruit flies has only very modest effects on sleep and locomotion compared to controls (Selkrig et al, 2018). Considering the wealth of literature describing the interconnection between the availability and quality of food on sleep, it is surprising that loss of gut microbiota has no effect on sleep (Selkrig et al, 2018).…”

“…While microbiome composition has been shown to affect mating choice (Sharon et al, 2010), egg laying, and feeding (Leitao-Goncalves et al, 2017), rather surprisingly, another study found that eliminating the microbiome in fruit flies has only very modest effects on sleep and locomotion compared to controls (Selkrig et al, 2018). Considering the wealth of literature describing the interconnection between the availability and quality of food on sleep, it is surprising that loss of gut microbiota has no effect on sleep (Selkrig et al, 2018). While admittedly we cannot definitive rule out whether microbiota composition has an effect on sleep; for now we can say with a degree of confidence that food-induced changes in sleep is mostly governed by taste and nutritional quality.…”