One of the best indicators of colony health for the European honey bee (Apis mellifera) is its performance in the production of honey. Recent research into the microbial communities naturally populating the bee gut raise the question as to whether there is a correlation between microbial community structure and colony productivity. In this work, we used 16S rRNA amplicon sequencing to explore the microbial composition associated with forager bees from honey bee colonies producing large amounts of surplus honey (productive) and compared them to colonies producing less (unproductive). As supported by previous work, the honey bee microbiome was found to be dominated by three major phyla: the Proteobacteria, Bacilli and Actinobacteria, within which we found a total of 23 different bacterial genera, including known “core” honey bee microbiome members. Using discriminant function analysis and correlation-based network analysis, we identified highly abundant members (such asFrischellaandGilliamella) as important in shaping the bacterial community; libraries from colonies with high quantities of theseOrbaceaemembers were also likely to contain fewerBifidobacteriaandLactobacillusspecies (such as Firm-4). However, co-culture assays, using isolates from these major clades, were unable to confirm any antagonistic interaction betweenGilliamellaand honey bee gut bacteria. Our results suggest that honey bee colony productivity is associated with increased bacterial diversity, although this mechanism behind this correlation has yet to be determined. Our results also suggest researchers should not base inferences of bacterial interactions solely on correlations found using sequencing. Instead, we suggest that depth of sequencing and library size can dramatically influencestatistically significantresults from sequence analysis of amplicons and should be cautiously interpreted.
The influence of conopid flies on bumble bee colony productivity under different food resource conditions
