The gut microbiota of insects – diversity in structure and function

Abstract

Insect guts present distinctive environments for microbial colonization, and bacteria in the gut potentially provide many beneficial services to their hosts. Insects display a wide range in degree of dependence on gut bacteria for basic functions. Most insect guts contain relatively few microbial species as compared to mammalian guts, but some insects harbor large gut communities of specialized bacteria. Others are colonized only opportunistically and sparsely by bacteria common in other environments. Insect digestive tracts vary extensively in morphology and physicochemical properties, factors that greatly influence microbial community structure. One obstacle to the evolution of intimate associations with gut microorganisms is the lack of dependable transmission routes between host individuals. Here, social insects, such as termites, ants, and bees, are exceptions: social interactions provide opportunities for transfer of gut bacteria, and some of the most distinctive and consistent gut communities, with specialized beneficial functions in nutrition and protection, have been found in social insect species. Still, gut bacteria of other insects have also been shown to contribute to nutrition, protection from parasites and pathogens, modulation of immune responses, and communication. The extent of these roles is still unclear and awaits further studies.

Feeding on ripening and over-ripening fruit: interactions between sugar, ethanol and polyphenol contents in a tropical butterfly

“…Indeed, the butterflies that we used in our experiment have been kept under laboratory conditions and have not been exposed to pathogens for generations. Consequently, if ethanol had microbicidal effects in butterflies, its effects would more likely occur on their gut microbiota rather than on potential pathogens, which in turn might reduce fitness components (Engel and Moran, 2013). Instead, the fact that The solution with low sugar concentration and no ethanol mimics unripe fruit, and the solution with low sugar concentration and ethanol mimics over-ripe fruit.…”

A novel intracellular mutualistic bacterium in the invasive ant Cardiocondyla obscurior

“…Symbionts can provide essential amino acids, vitamins or help in nitrogen recycling (Nakabachi et al, 2005;Feldhaar et al, 2007;Michalkova et al, 2014;Patino-Navarrete et al, 2014). Such bacteria are commonly harbored in bacteriocytes, specialized host cells that sometimes form special organ-like structures, the bacteriomes (Baumann, 2005) or are confined to the insect gut (Engel and Moran, 2013). Provisioning with nutrients can lead to increased fitness (Michalkova et al, 2014), which may enable invasive species to exploit novel habitats or food sources (Feldhaar, 2011).…”

Gut bacterial communities across tadpole ecomorphs in two diverse tropical anuran faunas

“…Assuming that the DNA-based approach here actually detects mostly bacteria living in the 591 gut of tadpoles and not DNA from bacteria ingested (and digested) as food, it remains to be 592 studied whether these communities represent intimate symbiotic associations with the host or 593 opportunistic colonization of the tadpole gut by nonspecific environmental bacteria, as it 594 seems to be common in many insects (Engel and Moran 2013). Our observation of multiple 595 shared OTUs between the core gut communities of tadpoles from two entirely different 596 geographical regions (Brazil and Madagascar), suggests that specific symbiotic relationships 597 between microbe and host may be the case for tadpoles.…”