Community structure of gut bacteria of Dendroctonus armandi (Coleoptera: Curculionidae: Scolytinae) larvae during overwintering stage.

Survival rate at low temperature becomes a crucial strategy since temperature change often leads to fluctuations in the insect population. Microbes play important roles in the process of resisting low temperature. In this study, we analyzed gut bacterial communities from Chinese white pine beetle Dendroctonus armandi which remained overwintering process under natural conditions from October 2015 to January 2016, monthly, in the Qinling Mountains, Shaanxi, China using Illumina MiSeq sequencing. A total of 835,227 high-quality sequences and 48 singleton operational taxonomic units were obtained. Gut bacterial communities showed variation in relative abundance during the overwintering stage. As ambient temperature declined, Proteobacteria (mostly γ-proteobacteria) became the predominant phylum in the larvae guts, and followed with Actinobacteria and Firmicutes, respectively. In particular, there was no Deinococcus-Thermus in January 2016. Thermoleophilia appeared in November and December 2015, but not for October 2015 and January 2016, nor did δ-proteobacteria. By contrast, gut bacterial community compositions increased in relative abundance in November and December 2015. This study provided initial evidence that gut bacterial communities were associated with the larvae overwintering process at low temperature. Moreover, no complementary studies combining overwintering process of Coleoptera insect and high-throughput sequencing were carried out, paying particular attention to insect in cold season.