Supporting wild bee development with a bacterial symbiont.

Aims: Wild bees foster diverse microbiota that may determine survival success of developing larvae. Here, we compare survivorship and microbial communities of Ceratina calcarata small carpenter bees reared from eggs across three treatments: maternally collected control provisions with diverse microbiota, sterile provisions, and probiotic provisions supplemented with a beneficial symbiont, Apilactobacillus kunkeei.

Methods And Results: Survival probability and adult masses differed across treatments, with the probiotic treatment resulting in highest survivorship and masses. By comparing the bacterial (16S rRNA), fungal (ITS), and plant (rbcL) communities of adults reared across treatments, we characterized distinct microbial communities across each that suggest the microbiome may be sensitive to microbial succession and competition.

Conclusions: We describe positive implications for the usage of probiotics on wild bees. Furthermore, the sensitivity of bee microbiota's relationships to their host, floral resources, and the environment suggests that holistic approaches best encapsulate the complex network of interactions between bees and their microbes.