Micro"bee"ota: Honey Bee Normal Microbiota as a Part of Superorganism

Abstract

Honey bees are model organisms for microbiota research. Gut microbiomes are very interesting for surveys due to their simple structure and relationship with hive production. Long-term studies reveal the gut microbiota patterns of various hive members, as well as the functions, sources, and interactions of the majority of its bacteria. But the fungal non-pathogenic part of gut microbiota is almost unexplored, likewise some other related microbiota. Honey bees, as superorganisms, interact with their own microorganisms, the microbial communities of food stores, hive surfaces, and other environments. Understanding microbiota diversity, its transition ways, and hive niche colonization control are necessary for understanding any separate microbiota niche because of their interplay. The long coevolution of bees with the microorganisms populating these niches makes these systems co-dependent, integrated, and stable. Interaction with the environment, hive, and other bees determines caste lifestyle as well as individual microbiota. In this article, we bring together studies on the microbiota of the western honey bee. We show a possible relationship between caste determination and microbiota composition. And what is primary: caste differentiation or microbiota composition?

Keywords: bacterial diversity; gut communities; hive; honey bee Apis mellifera; metagenome; symbiosis.

Figure 1

Types of honey bee-related microbiomes (according to [8,9,10]). There are 3 main groups of environments: bees, in-hive, and extra-hive. All microbiota there cannot strictly be divided to normal and pathogenic. Dotted lines depict the relationships between plant and in-hive microbiota. The developmental stages are linked by arrows. Ways of interaction and microorganism transmission are shown by color: blue for nurses, yellow for workers, and green for all hive members.

Figure 2

Amount and origins of main gut bacteria and fungi groups (according to [12,24,25,26,27,28,29,30,31,32,33,34,35,36,37]). Research on pylorus fungi has not been conducted yet. Number of microorganisms is provided on a relative scale. Probable environmental sources for community members are shown by color on pie charts on the right side.