Variation in Honey Bee Gut Microbial Diversity Affected by Ontogenetic Stage, Age and Geographic Location

Abstract

Social honey bees, Apis mellifera, host a set of distinct microbiota, which is similar across the continents and various honey bee species. Some of these bacteria, such as lactobacilli, have been linked to immunity and defence against pathogens. Pathogen defence is crucial, particularly in larval stages, as many pathogens affect the brood. However, information on larval microbiota is conflicting.Seven developmental stages and drones were sampled from 3 colonies at each of the 4 geographic locations of A. mellifera carnica, and the samples were maintained separately for analysis. We analysed the variation and abundance of important bacterial groups and taxa in the collected bees.Major bacterial groups were evaluated over the entire life of honey bee individuals, where digestive tracts of same aged bees were sampled in the course of time. The results showed that the microbial tract of 6-day-old 5th instar larvae were nearly equally rich in total microbial counts per total digestive tract weight as foraging bees, showing a high percentage of various lactobacilli (Firmicutes) and Gilliamella apicola (Gammaproteobacteria 1). However, during pupation, microbial counts were significantly reduced but recovered quickly by 6 days post-emergence. Between emergence and day 6, imago reached the highest counts of Firmicutes and Gammaproteobacteria, which then gradually declined with bee age. Redundancy analysis conducted using denaturing gradient gel electrophoresis identified bacterial species that were characteristic of each developmental stage.The results suggest that 3-day 4th instar larvae contain low microbial counts that increase 2-fold by day 6 and then decrease during pupation. Microbial succession of the imago begins soon after emergence. We found that bacterial counts do not show only yearly cycles within a colony, but vary on the individual level. Sampling and pooling adult bees or 6th day larvae may lead to high errors and variability, as both of these stages may be undergoing dynamic succession.

Honey bee gut microbial communities are robust to the fungicide Pristine® consumed in pollen

“…There is evidence that bee bread communities (Anderson et al 2014) and midgut/pyloric (Ludvigsen et al 2015) bacterial communities fluctuate with pollen source and season. Gut bacterial communities also can differ among colonies (Hroncova et al 2015). Bees for each of our experiments were sourced from different sets of colonies, and this might also have contributed to the differences we detected in gut microbiota between the experiments.…”

“…This diversity can change with age (Anderson et al 2015), season (Hroncova et al 2015;Ludvigsen et al 2015), and nutrition (Ludvigsen et al 2015;Saraiva et al 2015). In this study, we used high-throughput sequencing to examine the effects of feeding pollen with added Pristine® on the composition and diversity of microbial communities in the gut of nurse bees (i.e., worker bees that care for brood).…”

Microorganisms in Honey

“…New methodologies have made it possible to access information about the differences in the profile of this microbiota in different apiculture sources [118][119][120][121], species [53,122] and genetic diversity [116] of honeybees, development stages [53,68,117,[122][123][124][125][126], nutrition [116,127], location inside the gut [49,53,68] and digestive system [120], ontogenetic stage and geographic location [118,122,125], environmental conditions [128], health control [129], and individual [116,125].…”

“…This access has been carried out mainly by sequencing the coding region of the 16S subunit of the bacterial ribosome [53,121,130], both from genomic DNA from microorganisms growing on selective media as Man-Rogosa-Sharpe agar, Sabouraud dextrose agar, and Candida agar [117,120,131,132], such as process-independent culture as specific PCR [68], denaturing gradient gel electrophoresis [124,125], mixed and deep 16S sequencing [49,128], pyrosequencing [53,116,121], and clone library [115,118,120,122]. While culturedependent methods are ideal for quantification of microorganisms and phenotypic testing, culture-independent methods generally have greater coverage in relation to the amount of different species accessed and are ideal for fingerprinting studies, and the identification of these species may be performed by real-time PCR analysis [49,68,125,128].…”

“…While culturedependent methods are ideal for quantification of microorganisms and phenotypic testing, culture-independent methods generally have greater coverage in relation to the amount of different species accessed and are ideal for fingerprinting studies, and the identification of these species may be performed by real-time PCR analysis [49,68,125,128]. These methods, although they have different principles, were able to distinguish similarly the narrow niche of bacterial species and the diversity of strains present in these matrices [120].…”