Symbionts as Major Modulators of Insect Health: Lactic Acid Bacteria and Honeybees

TLDR

Lactic acid bacteria are known beneficial microbes in humans and animals, but their associations with invertebrates, including honeybees, remain poorly understood. The study proposes that enhancing or supplementing honeybee LAB could support pollinator health and that this microbiota will become central to research on honeybee health and colony collapse disorder. Honeybees harbor a diverse, ancient LAB community dominated by Lactobacillus kunkeei that protects against pathogens, includes many novel species, and is maintained in crop biofilms but can be disrupted by beekeeping practices.

Abstract

Lactic acid bacteria (LAB) are well recognized beneficial host-associated members of the microbiota of humans and animals. Yet LAB-associations of invertebrates have been poorly characterized and their functions remain obscure. Here we show that honeybees possess an abundant, diverse and ancient LAB microbiota in their honey crop with beneficial effects for bee health, defending them against microbial threats. Our studies of LAB in all extant honeybee species plus related apid bees reveal one of the largest collections of novel species from the genera Lactobacillus and Bifidobacterium ever discovered within a single insect and suggest a long (>80 mya) history of association. Bee associated microbiotas highlight Lactobacillus kunkeei as the dominant LAB member. Those showing potent antimicrobial properties are acquired by callow honey bee workers from nestmates and maintained within the crop in biofilms, though beekeeping management practices can negatively impact this microbiota. Prophylactic practices that enhance LAB, or supplementary feeding of LAB, may serve in integrated approaches to sustainable pollinator service provision. We anticipate this microbiota will become central to studies on honeybee health, including colony collapse disorder, and act as an exemplar case of insect-microbe symbiosis.