Overwintering does not affect microbiota diversity in Halyomorpha halys: implications for its ecology and management

Host-associated microbial communities play an important role in regulating many aspects of insect biology, but changes in this microbiota during diapause and overwintering are still largely unknown. Halyomorpha halys is an invasive agricultural pest characterised by a unique overwintering strategy where individuals aggregate and enter a state of dormancy, making it an excellent model to study the relationship between microbiota and diapause. We investigated the bacterial diversity of wild H. halys specimens before and after dormancy using 16S rRNA gene amplicon-sequencing. We found that microbiota varies between geographically neighbouring sampling locations, but there were no significant differences in microbial diversity or composition between populations sampled before and after diapause, despite stressful overwintering conditions. Such stability may relate to the highly specific taxa that dominate the stinkbug-associated microbial community. In addition, we did not detect any strong association of stink bugs with phytopathogens, but we found that two populations harboured Nosema maddoxi, a microsporidian pathogen of stink bugs. Our results are relevant to the assessment of accidental spillovers of microorganisms in newly invaded areas and to the implementation of the sterile insect technique based on mass trapping, irradiation, shipping and release after diapause of wild individuals