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About the Authors:
Svjetlana Vojvodic
* E-mail: [email protected]
Affiliation: Center for Insect Science, Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona, United States of America
Sandra M. Rehan
Affiliation: Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
Kirk E. Anderson
Affiliations Center for Insect Science, Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona, United States of America, United States Department of Agriculture, Tucson, Arizona, United States of America
Introduction
Insects are known to harbor microbial gut communities that provide protection from pathogens and contribute to nutrition. This is especially true for nutritionally limited organisms or those that subsist primarily on complex plant polymers [1]. Blood sucking insects and herbivorous insects in particular are believed to have coevolved with a number of bacterial and fungal symbionts that can aid in production of vitamins, nitrogen fixation and provide sterols [2]–[5]. In particular, acetic acid bacteria (AAB) are associated with insects that have sugar rich diets, and have been demonstrated to interact directly with the expression of antimicrobial peptides in the gut, affect larval development time, and contribute to cognitive function and general epithelial health [6]–[9]. Lactobacillus spp. in both solitary and social bees are thought to protect food stores and inhibit pathogenic microbes by lowering pH levels or producing secondary metabolites [10]–[12].
Results from non-cultured based sequencing indicate that adult honey bees have a distinct microbial gut community comprised of 7–12 core bacterial species belonging to the Acetobacteraceae, Betaprotobacteria, Gammaprotobacteria and Firmicutes [13]–[16]. While these studies focused primarily on the adult bee gut, non-cultured based studies of larvae have yielded minimal results. Direct PCR screening found that larvae were nearly devoid of putative core bacteria, with the exception of Alpha 2.2, an Acetobacteriaceae [14]. More extensive sampling found that last instar honey bee larvae harbored more diverse microbiota composed of both core and non-core bacteria [17]. Early culture-based work indicates that the minority of larvae contain microorganisms, suggesting that the presence of microbes in honey bee larvae is due to unwanted contamination [18], [19]. In general, microbial communities in the larval gut can differ dramatically from those of adults, revealing diverse groups of Gammaproteobacteria, Acetobacteraceae, Firmicutes, Bacillus spp., and various molds and yeast [17], [19], [20].
The...