Caste-specific gut symbionts contribute to the different adult longevity in the honeybee

Abstract

Background Honeybees are important pollinators, and their health is important to agricultural production and ecosystem. Queen-bees contain same genome as worker-bees, but live longer and healthier than worker-bees; thus, queen and worker pairs are natural biological models for studying longevity. Concerns are increasing regarding the relationship between gut microbes and honeybee health. We compared the hindgut microflora of queen and worker (Apis mellifera carpatica) by sequencing the bacterial 16S DNA, then salvaging the caste-specific microbes using LEfSe analysis and predicting the microbial functions using Tax4Fun, hoping to find potential gut symbionts associated with longevity. Results The hindgut microflora of queens differed from those of worker. Queens had higher abundances of Commensalibacter, Lactobacillus and Bifidobacterium than workers. The dominant microflora in the worker hindguts were Gilliamella (29.37%), Lactobacillus (15.28%), Commensalibacter (13.65%), Snodgrassella (11.56%), Bifidobacterium (6.07%) and Frischella (3.51%). The dominant microflora in the queen hindguts were Commensalibacter (44.89%), Lactobacillus (38.42%), Bifidobacterium (6.74%), Gilliamella (2.44%) and Bombella (2.41%). Queen-specific microbes was Bombella genus, and worker-specific microbes included Snodgrassella alvi, Frischella perrara and Gilliamella apicola. Queen and worker hindgut microbes exhibited diverse functions in lipid metabolism, neurodegenerative diseases, endocrine system, nervous system and immune system; those functions were linked to honeybee fitness and longevity. The queen-specific symbiont, Bombella, was predicted to be involved in host endocrine and immune regulation, which may contribute to queens living longer and healthier than worker bees. Conclusion The supernal Acetobacteraceae (especially Commensalibacter and Bombella), Lactobacillus and Bifidobacterium in the queen-hindgut help the queen bees live longer and healthier than the worker bees. This study may help determine the mechanisms of queen longevity and enable further understanding the positive roles of gut symbionts in honeybee fitness.