The Chinese white pine beetle Dendroctonus armandi Tsai and Li, is arguably the most destructive forest insect in the Qinling Mountains in Northern China. Little is known about the structure of the bacterial communities associated with D. armandi even though this wood-boring insect plays important roles in ecosystem and biological invasion processes that result in huge economic losses in pine forests. The aim of this study was to investigate the composition of the bacterial communities present in the guts of D. armandi at different developmental stages using a culture-independent method involving PCR-denaturing gradient gel electrophoresis (DGGE). Analysis of PCR-amplified 16S rRNA gene fragments of bacteria from the guts of larvae, pupae, and male and female adults revealed bacterial communities of low complexity that differed according to the developmental stage. Citrobacter spp. and Pantoea spp. predominated in larvae and adults, whereas Methylobacterium was the dominant genus at the pupal stage. The main difference between the guts of male and female adults was the greater dominance of Citrobacter in females. Previous studies suggest that the bacterial community associated with D. armandi guts may influence insect development. The data obtained in this study regarding the phylogenetic relationships and the community structure of intestinal bacteria at different developmental stages of the D. armandi life cycle contribute to our understanding of D. armandi and could aid the development of new pest control strategies.

The increased transcription levels of GST genes suggested that they have some relationship with the detoxification of terpenoids that are released by host trees. The mediating oxidative stress that is caused by monoterpene might be the main role of the bark beetle GSTs.

Aspergillus flavus is an important saprophytic fungus that produces aflatoxins (AF), which threaten food and feed safety. MAPK signaling pathways are essential for fungal adaptation to diverse environments.