Environment or kin: whence do bees obtain acidophilic bacteria?

Area of Science:

• Microbiology
• Ecology
• Entomology

Background:

• Declining bee populations have increased interest in bee-microorganism relationships.
• Honey bees and bumble bees harbor simple intestinal bacterial communities, including acidophilic bacteria.
• The acquisition and role of these bacteria in sweat bees remain largely unexplored.

Purpose of the Study:

• To investigate the hypothesis that sweat bees acquire acidophilic bacteria from their environment.
• To quantify bacterial communities associated with sweat bees, their brood cells, and nests.
• To understand the phylogenetic relationships of bee-associated Lactobacillus species and their environmental origins.

Main Methods:

• 16S rDNA amplicon 454 pyrosequencing was used to analyze bacterial communities.
• Bacterial communities were sampled from three sweat bee species (two North American, one Neotropical), their brood cells, and nests.
• Phylogenetic analysis was performed on the Lactobacillus genus to determine bacterial origins.

Main Results:

• Lactobacillus spp. were the most abundant bacteria in many sweat bee-associated samples.
• Lactobacilli related to flower-associated bacteria were found in all three sweat bee species.
• Sweat bee-associated lactobacilli were abundant in nest pollen and frass, suggesting a role in preventing spoilage.

Conclusions:

• Sweat bees acquire certain Lactobacillus species from environmental sources, particularly flowers.
• Some Lactobacillus strains may be vertically transmitted within bee populations, while others are acquired horizontally from the environment.
• Flower-associated lactobacilli found in sweat bee nests may inhibit the growth of molds and other spoilage organisms, contributing to bee health.