Noninvasive Analysis of Microbiome Dynamics in the Fruit Fly Drosophila melanogaster

The diversity and structure of the intestinal microbial community has a strong influence on life history. To understand how hosts and microbes interact, model organisms with comparatively simple microbial communities, such as the fruit fly (Drosophila melanogaster), offer key advantages. However, studies of the Drosophila microbiome are limited to a single point in time, because flies are typically sacrificed for DNA extraction. In order to test whether noninvasive approaches, such as sampling of fly feces, could be a means to assess fly-associated communities over time on the same cohort of flies, we compared the microbial communities of fly feces, dissected fly intestines, and whole flies across three different Drosophila strains. Bacterial species identified in either whole flies or isolated intestines were reproducibly found in feces samples. Although the bacterial communities of feces and intestinal samples were not identical, they shared similarities and obviously the same origin. In contrast to material from whole flies and intestines, feces samples were not compromised by Wolbachia spp. infections, which are widespread in laboratory and wild strains. In a proof-of-principle experiment, we showed that simple nutritional interventions, such as a high-fat diet or short-term starvation, had drastic and long-lasting effects on the micobiome. Thus, the analysis of feces can supplement the toolbox for microbiome studies in Drosophila, unleashing the full potential of such studies in time course experiments where multiple samples from single populations are obtained during aging, development, or experimental manipulations.     

Good mothers,bad mothers,and the nature of resistance to herbivory in <Emphasis Type="Italic">Solidago altissima</Emphasis>

Evidence of poor correspondence between an insect herbivore’s oviposition preferences and the performance of its offspring has generally been attributed either to maladaptive behavior of the insect mother or inadequate measurement by the researcher. In contrast, we hypothesize that many cases of “bad mothers” in herbivores may be a byproduct of the hierarchical way natural selection works on resistance in host plants. Epistatic selection on the components of resistance (i.e., antixenosis and antibiosis) may generate negative genetic correlations between the resistance components, which could counteract the efforts of herbivores to oviposit on the best hosts for the performance of their offspring. In common garden and greenhouse experiments, we measured aspects of antixenosis and antibiosis resistance in 26 genets of tall goldenrod, Solidago altissima, against two common herbivores: the gall-inducing fly Eurosta solidaginis and the spittlebug Philaenus spumarius. Goldenrod antixenosis and antibiosis were positively correlated against E. solidaginis and negatively correlated against P. spumarius. Analogously, population-wide preference–performance correlations were positive for the gall flies and negative for the spittlebugs. Several natural history differences between the two insects could make gall flies better mothers, including better synchrony of the phenologies of the flies and the host plant, the much narrower host range of the gall flies than the spittlebugs, and the more sedentary lifestyle of the gall fly larvae than the spittlebug nymphs. If these results are typical in nature, then negative genetic correlations in antixenosis and antibiosis in plants may often result in zero or negative population-wide correlations between preference and performance in herbivores, and thus may be an important reason why herbivorous insects often appear to be bad mothers.     

A Novel Method for Tracking Individuals of Fruit Fly Swarms Flying in a Laboratory Flight Arena

The growing interest in studying social behaviours of swarming fruit flies, Drosophila melanogaster, has heightened the need for developing tools that provide quantitative motion data. To achieve such a goal, multi-camera three-dimensional tracking technology is the key experimental gateway. We have developed a novel tracking system for tracking hundreds of fruit flies flying in a confined cubic flight arena. In addition to the proposed tracking algorithm, this work offers additional contributions in three aspects: body detection, orientation estimation, and data validation. To demonstrate the opportunities that the proposed system offers for generating high-throughput quantitative motion data, we conducted experiments on five experimental configurations. We also performed quantitative analysis on the kinematics and the spatial structure and the motion patterns of fruit fly swarms. We found that there exists an asymptotic distance between fruit flies in swarms as the population density increases. Further, we discovered the evidence for repulsive response when the distance between fruit flies approached the asymptotic distance. Overall, the proposed tracking system presents a powerful method for studying flight behaviours of fruit flies in a three-dimensional environment.     

The sensitivity of the labellar sugar receptors of Phormia regina in relation to feeding

The hypothesis that behavioural feeding threshold of P. regina modulates and is modulated by the sensitivity of the labellar contact chemoreceptors is not supported by the examination of individual flies.Sensitivity (number of impulses fired in the first second of stimulation) of the sugar receptors in selected labellar hairs of flies of known age was recorded periodically on a fixed schedule for up to 72 hr. Experimental flies were hand fed 2.0 M fructose once every 24 hr. No correlations between feeding or age and receptor sensitivity were found. Statistically significant changes in firing frequency did occur but were unrelated to feeding and age.The proboscis extension response, on which behavioural threshold measures are based, is known to be triggered by the first few sugar receptor spikes of sufficient frequency. Neither age nor feeding significantly affected the number or frequency of impulses during the first 50 msec of stimulation.     

Developmental plasticity of the locomotor activity rhythm of Drosophila melanogaster

We used four replicate outbred populations of Drosophila melanogaster to investigate whether the light regimes experienced during the pre-adult (larval and pupal) and early adult stages influence the free-running period (τ_DD) of the circadian locomotor activity rhythm of adult flies. In a series of two experiments four different populations of flies were raised from egg to eclosion in constant light (LL), in light/dark (LD) 12:12 h cycle, and in constant darkness (DD). In the first experiment the adult male and female flies were directly transferred into DD and their locomotor activity was monitored, while in the second experiment the locomotor activity of the emerging adult flies was first assayed in LD 12:12 h for 15 days and then in DD for another 15 days. The τ_DD of the locomotor activity rhythm of flies that were raised in all the three light regimes, LL, LD 12:12 h and in DD was significantly different from each other. The τ_DD of the locomotor activity rhythm of the flies, which were raised in DD during their pre-adult stages, was significantly shorter than that of flies that were raised as pre-adults in LL regime, which in turn was significantly shorter than that of flies raised in LD 12:12 h regime. This pattern was consistent across both the experiments. The results of our experiments serve to emphasise the fact that in order to draw meaningful inferences about circadian rhythm parameters in insects, adequate attention should be paid to control and specify the environment in which pre-adult rearing takes place. The pattern of pre-adult and early adult light regime effects that we see differs from that previously observed in studies of mutant strains of D. melanogaster, and therefore, also points to the potential importance of inter-strain differences in the response of circadian organisation to external influences.     

Genetics of Acetylcholinesterase in DROSOPHILA MELANOGASTER

Genes in Drosophila melanogaster that control acetylcholinesterase (AChE) were searched for by segmental aneuploidy techniques. Homogenates of flies containing duplications or deletions for different segments were assayed for enzyme activity. A region on the third chromosome was found for which flies having one does consistently gave lower AChE activity than euploid flies, which were in turn had lower activity than flies with three doses. The activity differences were in the approximate ratio 1:2:3. Fine structure deletion mapping within this region revealed a very small segment for which one-dose flies have approximately half-normal activity. To obtain putative AchE-null mutations, lethal mutations within this region were assayed. Four allelic lethals have approximately half-normal activity in heterozygous condition. These lethals probably define the structural locus (symbol: Ace) for AChE.     

Fine-scale genetic breaks driven by historical range dynamics and ongoing density-barrier effects in the estuarine seaweed Fucus ceranoides L.

Background

In the laboratory, the Drosophila melanogaster heat shock protein Hsp90 can buffer the phenotypic effects of genetic variation. Laboratory experiments either manipulate Hsp90 activity pharmacologically, or they induce mutations with strong effects in the gene Hsp83, the single-copy fly gene encoding Hsp90. It is unknown whether observations from such laboratory experiments are relevant in the wild.

Results

We here study naturally occurring mutations in Hsp83, and their effects on fitness and phenotypic buffering in flies derived from wild populations. We examined more than 4500 flies from 42 Drosophila populations distributed world-wide for insertions or deletions of mobile DNA in or near the Hsp83 gene. The insertions we observed occur at low population frequencies, and reduce Hsp83 gene expression. In competition experiments, mutant flies performed much more poorly than wild-type flies. Mutant flies were also significantly less fecund and shorter-lived than wild-type flies, as well as less well buffered against cryptic deleterious variation, as we show through inbreeding experiments. Specifically, in Hsp83 mutant flies female fecundity dropped to much lower levels after inbreeding than in wild-type flies. At even slightly elevated temperatures, inbred mutant Hsp83 populations went extinct, whereas inbred wild-type populations persisted.

Conclusions

Our work shows that Hsp90, a regulator of the stress response and of signaling, helps buffer deleterious variation in fruit flies derived from wild population, and that its buffering role becomes even more important under heat stress.     

Biosynthesis of contact sex pheromone in the female tsetse fly, Glossina morsitans morsitans Westwood

Injection of [2,3 ¹⁴C] sodium succinate into recently emerged, unfed females of Glossina morsitans morsitans resulted in incorporation of radiolabel mainly into surface cuticular alkanes. In vivo experiments with intact flies showed that the distribution of labelled alkanes depended on fly mobility, the legs of unrestrained flies possessing proportionately larger amounts of radioactive hydrocarbon material than those of flies whose legs were tied together with a silk suture. The heads of both restrained and unrestrained flies contained proportionately more material per unit surface area than did any other body part. However, ablation experiments and in vitro incubation showed that the most active incorporation of label into alkanes occurred in the abdomen and that all dorsal abdominal segments were equally active. The ventral abdomen also incorporated label into cuticular alkanes in vitro, but other body parts were apparently less able to do so. The sex pheromone of G. m. morsitans is a trimethyl-substituted alkane, the labelling of which appeared to be in proportion to the relative abundance of its methyl groups among those of the other alkanes of the cuticle following injection of either intact or legless flies. Hence it is proposed that sex pheromone is synthesized along with other cuticular alkanes mainly by cells closely associated with the abdominal cuticle of females and that it is spread over the external surface both by diffusion and by grooming which leads to accumulations of hydrocarbon material on the legs.     

Dynamics of follicle development and lipid storage in the tsetse fly Glossina palpalis palpalis fed on serum albumin deficient diets

Females of Glossina p. palpalis were fed on a mixture of bovine erythrocytes and a serum substitute which had been lyophilized, for a period of 30 days. The rate of ovarian development and lipid incorporation and the fatty acid composition of whole flies were examined at five-day intervals. Results showed that in flies fed serum albumin-deficient diets, ovarian development was seriously impaired and ovulation did not take place. Flies which were fed on a serum albumin-containing diet ovulated and produced larvae, though at a lower rate than control flies. Compared with controls, lipid incorporation was reduced in experimental flies, but more in the albumin-deficient group than in the albumin-containing group. The diet composition had no marked influence on the relative composition of fatty acids in any one group. It is concluded that, though an essential nutritional element for cow blood fed G. p. palpalis, serum albumin was not the only missing essential factor in the diets that were used in this study.     

The influence of ambient conditions and space on the phenological patterns of a Solenopsis phorid guild in an arid environment

We observed the diurnal distribution of a phorid parasitoid guild of Solenopsis fire ants across five sites in an arid region of western Argentina over 17-months. We found a rich assembly of 15 taxa, of which 7 species were found each month of the year and over most times of the day. The majority of species were found most frequently in the evening. A Canonical Correspondence Analysis of the hourly abundances of the flies in relation to field meteorological conditions suggested that two broad groups of species existed, one of which had flight periods associated with hotter, drier conditions than the second. The first group was most commonly represented by Pseudacteon tricuspis, the P. obtusus complex and P. cultellatus, while some members of the second group, such as the P. nocens complex and P. litoralis were the most abundant and commonly found flies. The range of conditions in which these flies were found suggests that all of the common taxa represent populations that might be suitable for introduction into similarly arid environments of Texas.     

Does a homogeneous population of elementary movement detectors activate the landing response of blowflies,Calliphora erythrocephala?

The landing response of tethered flying blowflies, Calliphora erythrocephala, was elicited by moving periodic gratings, and by stripes moving apart. The influence of binocular interactions on the landing response was investigated by comparing the responses of intact (“binocular”) animals to the response of flies which had one eye covered with black paint (“monocular” flies) effectively eliminating the input from this eye. Directions of motion eliciting a maximal response (preference direction) were determined in intact animals, and in “molecular” flies for different regions of the visual field. Preference directions determined in “monocular” flies follow the orientation of Z-axes (Fig. 4). Preference directions determined in intact animals and in “monocular” flies differ in the binocular eye region: in intact animals, the preference directions corresponds to vertical directions of motion; whereas the preference direction determined for the same area in “monocular” flies are inclined obliquely against the vertical plane. Sex-specific differences were found for the ventral binocular eye region in which the shift of preference directions is more pronounced in male than in female flies. The experimental data support the hypothesis that elementary movement detectors are aligned along the Z-axes of the eye, and that preference directions deviating from the orientation of elementary movement detectors are caused by binocular interactions.     

Tsetse blood-meal sources,endosymbionts and trypanosome-associations in the Maasai Mara National Reserve,a wildlife-human-livestock interface

African trypanosomiasis (AT) is a neglected disease of both humans and animals caused by Trypanosoma parasites, which are transmitted by obligate hematophagous tsetse flies (Glossina spp.). Knowledge on tsetse fly vertebrate hosts and the influence of tsetse endosymbionts on trypanosome presence, especially in wildlife-human-livestock interfaces, is limited. We identified tsetse species, their blood-meal sources, and correlations between endosymbionts and trypanosome presence in tsetse flies from the trypanosome-endemic Maasai Mara National Reserve (MMNR) in Kenya. Among 1167 tsetse flies (1136 Glossina pallidipes, 31 Glossina swynnertoni) collected from 10 sampling sites, 28 (2.4%) were positive by PCR for trypanosome DNA, most (17/28) being of Trypanosoma vivax species. Blood-meal analyses based on high-resolution melting analysis of vertebrate cytochrome c oxidase 1 and cytochrome b gene PCR products (n = 354) identified humans as the most common vertebrate host (37%), followed by hippopotamus (29.1%), African buffalo (26.3%), elephant (3.39%), and giraffe (0.84%). Flies positive for trypanosome DNA had fed on hippopotamus and buffalo. Tsetse flies were more likely to be positive for trypanosomes if they had the Sodalis glossinidius endosymbiont (P = 0.0002). These findings point to complex interactions of tsetse flies with trypanosomes, endosymbionts, and diverse vertebrate hosts in wildlife ecosystems such as in the MMNR, which should be considered in control programs. These interactions may contribute to the maintenance of tsetse populations and/or persistent circulation of African trypanosomes. Although the African buffalo is a key reservoir of AT, the higher proportion of hippopotamus blood-meals in flies with trypanosome DNA indicates that other wildlife species may be important in AT transmission. No trypanosomes associated with human disease were identified, but the high proportion of human blood-meals identified are indicative of human African trypanosomiasis risk. Our results add to existing data suggesting that Sodalis endosymbionts are associated with increased trypanosome presence in tsetse flies.     

Ecdysteroids in adult males and females of Drosophila melanogaster

Ecdysteroid titres in whole flies and different tissues of adult male and female Drosophila were determined at various times after eclosion using a radioimmunoassay. The ecdysteroid titre decreased as the flies matured after eclosion. The differences in titre between males and females can be accounted for by their difference in body weight. The ecdysteroids were found to be distributed throughout several tissues. At eclosion not all of the ecdysteroid complement present could be accounted for by that found localised in tissues. After maturation of the flies the ecdysteroids in various tissues can account for the majority of that detected in whole-fly extracts. Ecdysteroids were produced during in vitro culture of various tissues, but the quantities detected were low by comparison with ring glands of wandering 3rd-instar larvae. Neither the ovaries nor the abdominal body walls (fat body) seem to be a major source of hormone, and they are only able to convert minute quantities of ecdysone to the biologically active form, 20-hydroxyecdysone, in vitro. The amounts of 20-hydroxyecdysone present were measured using high performance liquid chromatography and radioimmunoassay. We tentatively suggest that the differential experession of the yolk-protein-genes in the fat bodies of males and females does not result from differences in hormone titres between them.     

The FlyBar: Administering Alcohol to Flies

Fruit flies (Drosophila melanogaster) are an established model for both alcohol research and circadian biology. Recently, we showed that the circadian clock modulates alcohol sensitivity, but not the formation of tolerance. Here, we describe our protocol in detail. Alcohol is administered to the flies using the FlyBar. In this setup, saturated alcohol vapor is mixed with humidified air in set proportions, and administered to the flies in four tubes simultaneously. Flies are reared under standardized conditions in order to minimize variation between the replicates. Three-day old flies of different genotypes or treatments are used for the experiments, preferably by matching flies of two different time points (e.g., CT 5 and CT 17) making direct comparisons possible. During the experiment, flies are exposed for 1 hr to the pre-determined percentage of alcohol vapor and the number of flies that exhibit the Loss of Righting reflex (LoRR) or sedation are counted every 5 min. The data can be analyzed using three different statistical approaches. The first is to determine the time at which 50% of the flies have lost their righting reflex and use an Analysis of the Variance (ANOVA) to determine whether significant differences exist between time points. The second is to determine the percentage flies that show LoRR after a specified number of minutes, followed by an ANOVA analysis. The last method is to analyze the whole times series using multivariate statistics. The protocol can also be used for non-circadian experiments or comparisons between genotypes.     

Strain-differences and inducibility of microsomal oxidative enzymes in Drosophila melanogaster flies

Some basic characteristics of the enzyme system involved in the oxidative metabolism of xenobiotic compounds were investigated in Drosophila melanogaster flies. Attention was focussed on (1) the normal levels of these enzymes and their activities in whole flies, in different parts of the fly's body and in different sexes, (2) the changes in levels and activities of the enzymes elicited by pretreatment of the flies with known enzyme inducers and (3) differences between strains.Four commonly used wild-type (WT) strains, three insecticide resistant strains (IR) and one white-eyed mutant strain were employed. Except in those experiments on sex differences and in spatial distribution in the fly's body of the enzymatic activities, microsomes were isolated from whole-body homogenates of mixtures of female and male flies. Microsomal cytochrome P-450, benzo[a]pyrene (BP) hydroxylation, p-nitroanisole (pNA) demethylation and aminopyrine (AP) demethylation were measured in control flies and in flies pretreated with Aroclor 1254 (AC), phenobarbital (PB) or butylated hydroxytoluene (BHT).In flies of the WT strain Berlin-K, there were no significant differences in BP hydroxylation activity and its inducibility between the two sexes. In males, inducibility of BP hydroxylation activity was similar in the head, thorax and abdomen, but significantly lower in testis. Considerable differences in some enzyme activities were found between the strains. pNA demethylation and AP demethylation were substantially higher in all IR strains, while no correlation could be found between their increased insecticide resistance and BP hydroxylating capacity or cytochrome P-450 content of the microsomes.Response to enzyme inducing compounds was found to be strain-dependent. PB proved to be a more efficient inducer of BP hydroxylation than AC, which does induce pNA demethylation. BHT has inducing properties that are intermediate between PB and AC. IR strain Hikone-R turned out to be an exception, possessing very low BP hydroxylating capacity and a low degree of inducibility of mixed-function oxidase activities. Differential temperature dependence was found for BP hydroxylation as compared with pNA demethylation. While BP hydroxylation was doubled when raising the temperature from 25°C to 35°C, pNA demethylation was reduced by 50%.     

Evolutionary ecology of learning: insights from fruit flies

Ecologically and evolutionarily oriented research on learning has traditionally been carried out on vertebrates and bees. While less sophisticated than those animals, fruit flies (Drosophila) are capable of several forms of learning, and have the advantage of a short generation time, which makes them an ideal system for experimental evolution studies. This review summarizes the insights into evolutionary questions about learning gained in the last decade from evolutionary experiments on Drosophila. These experiments demonstrate that Drosophila has the genetic potential to evolve a substantially improved learning performance in ecologically relevant learning tasks. In at least one set of selected populations, the improved learning generalized to a task other than that used to impose selection, involving a different behavior, different stimuli, and a different sensory channel for the aversive reinforcement. This improvement in learning ability was associated with reductions in other fitness-related traits, such as larval competitive ability and lifespan, pointing to evolutionary trade-offs for improved learning. These trade-offs were confirmed by other evolutionary experiments where a reduction in learning performance was observed as a correlated response to selection for tolerance to larval nutritional stress or for delayed aging. Such trade-offs could be one reason why fruit flies have not fully used up their evolutionary potential for learning. Finally, another evolutionary experiment with Drosophila provided the first direct evidence for the long-standing idea that learning can under some circumstances accelerate and in others slow down genetically based evolutionary change. These results demonstrate the usefulness of fruit flies as a model system to address evolutionary questions about learning.     

Classical Olfactory Conditioning in the Oriental Fruit Fly,Bactrocera dorsalis

The oriental fruit fly, Bactrocera dorsalis, is a serious pest of fruits and vegetables. Methyl eugenol (ME), a male attractant, is used to against this fly by mass trapping. Control effect may be influenced by learning, which could modify the olfactory response of the fly to this attractant. To collect the behavioral evidence, studies on the capability of this fly for olfactory learning are necessary. We investigated olfactory learning in male flies with a classical olfactory conditioning procedure using restrained individuals under laboratory conditions. The acquisition of the proboscis extension reflex was used as the criterion for conditioning. A high conditioned response level was found in oriental fruit flies when an odor was presented in paired association with a sucrose reward but not when the odor and sucrose were presented unpaired. We also found that the conditioning performance was influenced by the odor concentration, intertrial interval, and starvation time. A slight sensitization elicited by imbibing sucrose was observed. These results indicate that oriental fruit flies have a high capacity to form an olfactory memory as a result of classical conditioning.     

Behavioral responses of a parasitoid fly to rapidly evolving host signals

Animals eavesdrop on signals and cues generated by prey, predators, hosts, parasites, competing species, and conspecifics, and the conspicuousness of sexual signals makes them particularly susceptible. Yet, when sexual signals evolve, most attention is paid to impacts on intended receivers (potential mates) rather than fitness consequences for eavesdroppers. Using the rapidly evolving interaction between the Pacific field cricket, Teleogryllus oceanicus, and the parasitoid fly, Ormia ochracea, we asked how parasitoids initially respond to novel changes in host signals. We recently discovered a novel sexual signal, purring song, in Hawaiian populations of T. oceanicus that appears to have evolved because it protects the cricket from the parasitoid while still allowing males to attract female crickets for mating. In Hawaii, there are no known alternative hosts for the parasitoid, so we would expect flies to be under selection to detect and attend to the new purring song. We used complementary field and laboratory phonotaxis experiments to test fly responses to purring songs that varied in many dimensions, as well as to ancestral song. We found that flies strongly prefer ancestral song over purring songs in both the field and the lab, but we caught more flies to purring songs in the field than reported in previous work, indicating that flies may be exerting some selective pressure on the novel song. When played at realistic amplitudes, we found no preferences–flies responded equally to all purrs that varied in frequency, broadbandedness, and temporal measures. However, our lab experiment did reveal the first evidence of preference for purring song amplitude, as flies were more attracted to purrs played at amplitudes greater than naturally occurring purring songs. As purring becomes more common throughout Hawaii, flies that can use purring song to locate hosts should be favored by selection and increase in frequency.     

Do Gravid Black Flies (Diptera: Simuliidae) Oviposit at Their Natal Site?

We present information on an aniline dye marking method for black flies. In the laboratory, adults were sprayed with 2% aqueous solutions of four colors of aniline dyes; brilliant blue and methyl orange gave the best results in longevity trials. In field trials we were able to recapture 1.3% of newly emerged marked and released flies at oviposition sites. Mark–release–recapture experiments were designed to distinguish among three competing models concerning oviposition site selection by gravid female black flies: (1) larval site fidelity (“Do flies return to the site that they experienced as larvae?”), (2) adult site fidelity (“Do flies return to the site that they experienced as adults?”), and (3) no site fidelity (“Do flies oviposit at random, i.e., without regard to adult or larval experience?”). Models 1 and 2 were rejected. There is, however, no reason to reject Model 3, the no site fidelity model. Thus, we conclude that for members of the S. venustum/verecundum complex (i.e., S. rostratum, S. venustum, and S. truncatum) females find an “apparently suitable” waterway in which to oviposit; this may or may not be their natal site.     

Impact of the Chromatin Remodeling Factor CHD1 on Gut Microbiome Composition of Drosophila melanogaster

The composition of the intestinal microbiota of Drosophila has been studied in some detail in recent years. Environmental, developmental and host-specific genetic factors influence microbiome composition in the fly. Our previous work has indicated that intestinal bacterial load can be affected by chromatin-targeted regulatory mechanisms. Here we studied a potential role of the conserved chromatin assembly and remodeling factor CHD1 in the shaping of the gut microbiome in Drosophila melanogaster. Using high-throughput sequencing of 16S rRNA gene amplicons, we found that Chd1 deletion mutant flies exhibit significantly reduced microbial diversity compared to rescued control strains. Specifically, although Acetobacteraceae dominated the microbiota of both Chd1 wild-type and mutant guts, Chd1 mutants were virtually monoassociated with this bacterial family, whereas in control flies other bacterial taxa constituted ~20% of the microbiome. We further show age-linked differences in microbial load and microbiota composition between Chd1 mutant and control flies. Finally, diet supplementation experiments with Lactobacillus plantarum revealed that, in contrast to wild-type flies, Chd1 mutant flies were unable to maintain higher L. plantarum titres over time. Collectively, these data provide evidence that loss of the chromatin remodeler CHD1 has a major impact on the gut microbiome of Drosophila melanogaster.