Impacts of a glyphosate-based herbicide on the gut microbiome of three earthworm species ( and ): A pilot study.

While the impact of glyphosate-based herbicides (GBHs) on earthworms has been studied, little is known about their effects on the earthworm gut microbiome. This study investigated the impact of a GBH on the gut microbial communities of three earthworm species ( and ). Earthworm species accommodated in soil were sprayed with 115.49 mL/m² of Roundup® Alphée or water. Gut microbiome composition was analysed using 16S rRNA Bacterial Tag-Encoded FLX Amplicon Pyrosequencing (bTEFAP) at the 8th week post-herbicide application. A profound shift in bacterial populationswas observed in all exposed earthworms with becoming the dominant phylum. Affected bacteria were mostly from the genus , and , which together represented approximately 80 % of the total abundance assigned at the genus level in exposed earthworms, while they were present at a minor abundance (∼1%) in unexposed earthworms. Although consistent results were observed between the three groups of worm species, it is not possible to generalize these outcomes due to a lack of biological replicates, which does not allow for inferential statistical analysis. Nevertheless, our study is the first to report the effects of a GBH on the earthworm gut microbiome and paves the way for future more comprehensive investigations.