Supplementary Information - Chapter 2. Metabarcoding and genomic analysis of two insecticide-degrading bacteria in E. heros (Hemiptera: Pentatomidae) led to the identification of a new insect-associated Serratia species

The microbiota plays a diverse role in their hosts life. Insect-associated microbes can play a role in host nutrition, immunity, stress response, and xenobiotic metabolization, including synthetic pesticides. Gut associated insecticide-degrading bacteria are also selected by the selection pressure of intensive insecticide exposure as their hosts. For this reason, this study aimed at investigating the influence of the evolution of E. heros resistance to the neonicotinoid thiamethoxam and the pyrethroid lambda-cyhalothrin on the diversity of the gut microbiota, as well as to identify and characterize insecticide-degrading bacteria using comparative genomics strategies. We compared the gut microbiota composition of lab-maintained susceptible and insecticide-resistant strains and of field-collected adults of E. heros. The diversity of the gut microbiota was assessed using metabarcoding analysis of the V3-V4 regions of the 16S ribosomal gene (16S rRNA). The gut microbiota analysis of Euschistus heros revealed a predominance of Pseudomonadota - Gammaproteobacteria, which plays a key role in the insect gut environment. The Enterobacteriaceae Yokenella and Serratia, and the Erwiniaceae Pantoea and Erwinia were the most represented in the gut microbiota of E. heros. The gut microbial diversity of laboratory reared strains was higher than that of field-collected adults. The abundance of Serratia, Siccibacter, and Pantoea was enriched in the pyrethroid-resistant strains (RESPYR), and Serratia and Siccibacter were identified as potential biomarkers for pyrethroid-resistance. Two insecticide-degrading bacteria were isolated from the gut of E. heros and identified as Delftia acidovorans and Serratia toxivorans n. sp. using genomic comparative analyses. Our data emphasizes the importance of microbiota in metabolizing toxic compounds, and that the associated microbiota as well as the host are under selection pressure.