Seasonal Shifts in Cold Tolerance and the Composition of the Gut Microbiome of Dendroctonus valens LeConte Occur Concurrently

Abstract

Dendroctonus valens LeConte, an invasive bark beetle, has caused severe damage in pine forests and has the potential to disperse into new geographic ranges in China. Although the gut microbiota of D. valens and its fundamental role in host fitness have been investigated widely, little is known about the relationship between the seasonal shifts of both cold tolerance and the gut microbiome of D. valens during overwintering, which occurs at the larval stage. In this study, to examine seasonal variations in the composition of the microbiome, we collected D. valens larvae in September (autumn), January (winter), and May (spring), and then analyzed the bacterial and fungal communities of the gut via sequencing of partial 16S rRNA and ITS genes. In addition, changes in the supercooling capacity and antioxidant enzyme activities of D. valens larvae collected in the different seasons were evaluated. Overwintering resulted in changes to microbial communities. In particular, the abundances of Enterobacter, Serratia, Erwinia, and Klebsiella decreased during overwintering. Concurrent with these changes, the cold tolerance of D. valens larvae was enhanced during overwintering, and the activities of the antioxidant enzymes catalase and peroxidase were reduced. We hypothesize that seasonal shifts in the gut microbiome may be connected to changes in cold tolerance and antioxidant enzyme activity in D. valens. It will be worthwhile to confirm whether seasonal changes in the microbiome contribute to the success of host overwintering.

Seasonal variations in the composition and functional profiles of gut microbiota reflect dietary changes in plateau pikas

“…Both hibernating and non‐hibernating animals will make adaptive changes in metabolic physiological characteristics for overwintering, which then may have an impact on their gut microbiota (Hou et al . 2021 ; Speakman et al . 2021 ).…”

“…Plateau pika has seasonal reproductive characteristics (Li et al 1998) and these may affect their internal bacteria. Both hibernating and non-hibernating animals will make adaptive changes in metabolic physiological characteristics for overwintering, which then may have an impact on their gut microbiota (Hou et al 2021;Speakman et al 2021). Additionally, dispersal patterns also play a role in influencing microbial communities, sometimes to an even greater extent than other selective pressures (Stothart et al 2021), and could be further reflected in geographic, family, or host associations (Grant et al 2019;Hildebrand et al 2021).…”

Natural diversity of the honey bee (Apis mellifera) gut bacteriome in various climatic and seasonal states

“…bacteriome is not fully transitioned to the summer state, to a bacteriome characteristic to summer, where apiary level and regional differences can shape its composition. Bacteriomes in the winter can show substantial differences in different insect species [56,57]. However, during the honey-producing season, a more even distribution of species can be observed in foragers, with Gilliamella being one of the most abundant members.…”

The bacterial community of the European spruce bark beetle in space and time

“…Seasonal variations and diapause behavior might influence the bacterial community structure and the latter could support the insect in overcoming the harsh winter conditions, for instance by nutrient storage to build up energy reserves. A change in the bacterial community structure across the season and during overwintering was observed in Dendroctonus bark beetles (Wang et al 2017;Hou et al 2021). By comparing populations sampled before and during the overwintering phase, we found a significant difference of the microbial community.…”