Romoli, Ottavia, Epelboin, Yanouk, Pavoncello, Viola, Barras, Frederic, Behrends, Volker ORCID: https://orcid.org/0000-0003-4855-5497 and Gendrin, Matilde (2026) The microbiota affects energy production, nitrogen excretion, and sterol metabolism in mosquito larvae. mBio.

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Abstract

Mosquito larvae rely on a living microbiota for normal development because the microbiota supplies essential nutrients, particularly vitamins. Beyond vitamin provision, transcriptomic data suggest that the microbiota also supports other key nutritional processes. Here, we explored these roles by conducting a metabolomics analysis on Aedes aegypti third instar larvae following microbiota depletion. We sampled larvae and dissected guts 12 and 20 h post-decolonization, and analysed methanol-soluble metabolites using untargeted gas chromatography–mass spectrometry. Our findings reveal a pronounced impact of gut microbial presence on several metabolites involved in the tricarboxylic acid cycle and the uricolytic pathway. Germ-free larvae also had a lower quantity of cholesterol in their guts, and their long-chain fatty acid profile was altered in their guts and whole larvae. Sterols, including cholesterol, are essential precursors for the production of the molting hormone 20-hydroxyecdysone. We therefore tested how supplementing exogenous cholesterol affects the development of germ-free larvae. The effects proved to be highly concentration-dependent, ranging from a marginally significant increase in successful development to adulthood at low concentrations, to a pronounced developmental impairment at higher concentrations. Moreover, bacteria deficient in fatty acid beta-oxidation had a significantly lower ability to support larval development. Together, the observed alterations suggest that microbiota-deprived larvae exhibit a downregulation of metabolic processes related to energy production, nitrogen excretion, and sterol metabolism, likely due to the absence of microbiota-derived vitamins essential for these central metabolic functions.

Item Type:	Article
Identifier:	10.1128/mbio.01035-26
Keywords:	mosquito, Aedes aegypti, larval development, metabolome, GC-MS, microbiota, transient colonization, nitrogen metabolism, TCA cycle, cholesterol, fatty acids, beta-oxidation
Subjects:	Medicine and health > Microbiology
Date Deposited:	16 Jun 2026
Dates:	Date Publication status 6 May 2026 Accepted 12 June 2026 Published
School, department or research centre:	School of Medicine and Biosciences
Keywords:	mosquito, Aedes aegypti, larval development, metabolome, GC-MS, microbiota, transient colonization, nitrogen metabolism, TCA cycle, cholesterol, fatty acids, beta-oxidation
URI:	https://repository.uwl.ac.uk/id/eprint/15049

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