Antibiotic exposure perturbs the gut microbiota and elevates mortality in honeybees

Abstract

Gut microbiomes play crucial roles in animal health, and shifts in the gut microbial community structure can have detrimental impacts on hosts. Studies with vertebrate models and human subjects suggest that antibiotic treatments greatly perturb the native gut community, thereby facilitating proliferation of pathogens. In fact, persistent infections following antibiotic treatment are a major medical issue. In apiculture, antibiotics are frequently used to prevent bacterial infections of larval bees, but the impact of antibiotic-induced dysbiosis (microbial imbalance) on bee health and susceptibility to disease has not been fully elucidated. Here, we evaluated the effects of antibiotic exposure on the size and composition of honeybee gut communities. We monitored the survivorship of bees following antibiotic treatment in order to determine if dysbiosis of the gut microbiome impacts honeybee health, and we performed experiments to determine whether antibiotic exposure increases susceptibility to infection by opportunistic pathogens. Our results show that antibiotic treatment can have persistent effects on both the size and composition of the honeybee gut microbiome. Antibiotic exposure resulted in decreased survivorship, both in the hive and in laboratory experiments in which bees were exposed to opportunistic bacterial pathogens. Together, these results suggest that dysbiosis resulting from antibiotic exposure affects bee health, in part due to increased susceptibility to ubiquitous opportunistic pathogens. Not only do our results highlight the importance of the gut microbiome in honeybee health, but they also provide insights into how antibiotic treatment affects microbial communities and host health.

Genetic Engineering of Bee Gut Microbiome Bacteria with a Toolkit for Modular Assembly of Broad-Host-Range Plasmids

“…Previous studies have examined how S. alvi colonizes the honey bee gut, 31,49 but colonization by G. apicola , B. apis , and S. marcescens has not been investigated. 26,34 …”

“…26 Like the human gut microbiome, the BGM is socially acquired and transmitted 27 and has a history of antibiotic exposure. 22,26,28,29 Major members of the core BGM — Snodgrassella alvi , Gilliamella apicola , and Bartonella apis — have been the subject of detailed genomic analyses. 30–32 But aside from random transposon mutagenesis in S. alvi , 33 no genetic tools have been reported for these species.…”

The role of the gut microbiome in health and disease of adult honey bee workers

“…Serratia marcescens strains can be pathogenic, causing sepsis and death [23 • ]. Strains isolated from hives can cause mortality when administered orally to workers in the laboratory [24 •• ]. Potentially, these Enterobacteriaceae pathogens are under-recognized as causes of bee mortality, since infected bees usually leave the hive to die; they are more likely to accumulate in wintering hives [23 • ].…”

“…Oxy-tetracycline has been used for decades in beekeeping in the USA, and strains of bee gut bacterial species have acquired several tetracycline resistance loci, with frequencies highest in colonies exposed more recently [32]. Tetracycline exposure results in severe gut dysbiosis, with drastic and persistent effects on microbiome size and composition [24 •• ]. The treatment also increases mortality in the hive, potentially due to greater susceptibility to opportunistic pathogens, as observed in the lab [24 •• ].…”

Effect of water and resource availability on ant feeding preferences: a field experiment on the Mediterranean ant Crematogaster scutellaris

“…Genomic analyses and recent functional experimental studies suggest that this core microbial community is involved in a range of key functions including nutrition and health (Engel et al 2012;Kwong et al 2014;Engel et al 2014;Lee et al 2015;Ellegaard et al 2015;Engel et al 2015;Raymann et al 2017;Zheng et al 2017;Kešnerová et al 2017). Specifically, the gut community of worker honey bees is dominated by nine bacterial species clusters that make up 95-98% of the community (Jeyaprakash et al 2003;Babendreier et al 2006;Martinson et al 2011;Moran et al 2012;Sabree et al 2012;CorbyHarris et al 2014;Kwong et al 2017).…”