Microbial communities of the house fly Musca domestica vary with geographical location and habitat

Abstract

House flies (Musca domestica) are widespread, synanthropic filth flies commonly found on decaying matter, garbage, and feces as well as human food. They have been shown to vector microbes, including clinically relevant pathogens. Previous studies have demonstrated that house flies carry a complex and variable prokaryotic microbiota, but the main drivers underlying this variability and the influence of habitat on the microbiota remain understudied. Moreover, the differences between the external and internal microbiota and the eukaryotic components have not been examined. To obtain a comprehensive view of the fly microbiota and its environmental drivers, we sampled over 400 flies from two geographically distinct countries (Belgium and Rwanda) and three different environments—farms, homes, and hospitals. Both the internal as well as external microbiota of the house flies were studied, using amplicon sequencing targeting both bacteria and fungi. Results show that the house fly’s internal bacterial community is very diverse yet relatively consistent across geographic location and habitat, dominated by genera Staphylococcus and Weissella. The external bacterial community, however, varies with geographic location and habitat. The fly fungal microbiota carries a distinct signature correlating with the country of sampling, with order Capnodiales and genus Wallemia dominating Belgian flies and genus Cladosporium dominating Rwandan fly samples. Together, our results reveal an intricate country-specific pattern for fungal communities, a relatively stable internal bacterial microbiota and a variable external bacterial microbiota that depends on geographical location and habitat. These findings suggest that vectoring of a wide spectrum of environmental microbes occurs principally through the external fly body surface, while the internal microbiome is likely more limited by fly physiology.

Environmental and Sex Effects on Bacterial Carriage by Adult House Flies (Musca domestica L.)

“…Our results also corroborated those from other studies, by demonstrating that house flies carry AMR and MDR bacteria in areas of livestock agriculture. A thorough assessment of the role flies play in harboring and disseminating bacteria, including AMR and MDR strains, and pathogens, is actively being investigated [8,10,12,[55][56][57], risk assessment models (e.g., [58]) can be enhanced by identifying and including variables related to bacterial source, the role of fly sex, environmental niche, fly dispersal patterns and farm management practices. Overall, we provide evidence of sex-specific effects on culturable bacterial load that includes AMR and MDR bacteria.…”

“…Wild house flies harbor both pathogenic and nonpathogenic bacteria [6,8,9], including those that are antimicrobial resistant (AMR) [10,11]. Because flies associate with a wide variety of microbe rich sites across the landscape, it is not surprising that they harbor different microbial communities associated with the sites with which they interact [12].…”

Saccharomyces cerevisiae – Insects Association: Impacts, Biogeography, and Extent

“…Similarly, bees only accidentally bear S. cerevisiae , with only 1 occurrence over 21 reported cases ( Sandhu and Waraich, 1985 ; Lachance et al, 2003 ; Rosa et al, 2003 ; Daniel et al, 2013 ; Charron et al, 2014 ; Saksinchai et al, 2015 ). Conversely, S. cerevisiae has been found in a large portion of investigated flies, fruit flies, honey-bees, and wasps (29, 57, 20, and 71%, respectively) ( Phaff and Knapp, 1956 ; Batra et al, 1973 ; Sandhu and Waraich, 1985 ; Morais et al, 1993 , 1994 ; Rosa et al, 1994 ; Lachance et al, 1995 , 2003 , 2006 ; Suh et al, 2005 ; Nguyen et al, 2006 , 2007 ; Basukriadi et al, 2010 ; Goddard et al, 2010 ; Chandler et al, 2012 ; de Vega et al, 2012 ; Hamby et al, 2012 ; Stefanini et al, 2012 ; Freitas et al, 2013 ; Buser et al, 2014 ; Charron et al, 2014 ; Lam and Howell, 2015 ; Saksinchai et al, 2015 ; Batista et al, 2017 ; Deutscher et al, 2017 ; Jimenez et al, 2017 ; Piper et al, 2017 ; Quan and Eisen, 2018 ; Siavoshi et al, 2018 ; dos Santos et al, 2019 ; Meriggi et al, 2019 ; Park et al, 2019 ). A few possible scenarios could explain the higher occurrence of S. cerevisiae in these groups of insects: (i) they are more prone to visit human-related environments, such as wineries and vineyards, that are likely to host higher amounts of S. cerevisiae cells, (ii) they are more attracted by substrates inhabited by the budding yeast compared to other insects, (iii) diet and physical-chemical intestine conditions facilitate the housing of S. cerevisiae .…”

Ontogeny, species identity, and environment dominate microbiome dynamics in wild populations of kissing bugs (Triatominae)

“…In some cases, the differences reflect the phylogenetic relationships of the hosts (phylosymbiosis, e.g., [ 35 ]). On the other hand, since environment is a natural source of at least some portion of the microbiomes, the habitat and geographic location of the host may significantly affect microbiome composition (e.g., [ 36 – 39 ]). In triatomines, thirteen high throughput sequencing studies published since 2015 have indicated a wide range of factors that potentially influence their microbiomes.…”