Host trees partially explain the complex bacterial communities of two threatened saproxylic beetles

Area of Science:

• Ecology
• Microbiology
• Entomology

Background:

• Microorganisms are crucial for ecosystem function and host adaptation.
• Understanding insect microbiomes is vital, yet knowledge gaps exist for many beetle species.
• Red flat bark beetles (Cucujus spp.) are important in forest ecosystems.

Purpose of the Study:

• To investigate the microbial composition of two red flat bark beetle species (Cucujus haematodes and C. cinnaberinus).
• To assess the impact of host taxonomic relatedness and host tree species on beetle microbiomes.
• To elucidate the ecological factors influencing insect-microbe interactions in saproxylic beetles.

Main Methods:

• Sampling of 67 larvae from two Cucujus taxa across 11 host tree species.
• 16S rRNA V4 fragment sequencing for microbial community analysis.
• Statistical analyses including alpha/beta diversity and principal component analysis.

Main Results:

• Distinct microbial communities were identified for each Cucujus species.
• Host tree species significantly influenced microbiome composition, more so than beetle species.
• Microbial communities in beetles and host trees showed significant differences and distinct clustering by host tree.

Conclusions:

• Host tree species is a primary driver of microbiome composition in red flat bark beetles.
• The similar ecology of Cucujus species may explain the overlap in their microbial communities.
• Findings underscore the complex interplay of host, microhabitat, and microbial communities, with implications for conservation and forest ecosystem understanding.