Metagenomic profiling of the digestive tract of an invasive scarab beetle larvae and associated soil

Invasive scarab beetles, like the Japenese beetle Popillia japonica Newman (JB), spend most of their lives as larvae feeding in the soil matrix where they also acquire a significant portion of their gut microbiota. With this in mind, we aimed to understand the reciprocal effects of JB larval invasion on the soil prokaryotic microbiome. We compared uninfested soil to JB-infested soil over the short-term (96 hrs) under laboratory conditions, and over the longer-term under field conditions. The influence of JB infestation on soil prokaryotic diversity varied with the duration of infestation (field vs. laboratory), with duration explaining most of the variability in both bacterial (R²=68.9%) and archaeal (R²=48.2%) communities. Although prokaryotic community composition did not vary over the short-term as a result of infestation in the laboratory, infested and uninfested soils from the field exhibited significantly different prokaryotic communities. The functional profile of the prokaryotic metagenome in soils from the field revealed different relative abundances of 34 functions with infested soils presenting a higher relative abundance of 12 functions, including those involved in the biosynthesis of amino acids, cofactors and vitamins, steroid hormones, and secondary metabolites with antimicrobial activity. Findings indicate that naturally occurring JB larval infestations provoke changes in the soil prokaryotic community at both taxonomic and functional levels.