Pathogens are considered one of the largest contributing factors in the global decline of honey bees (Apis mellifera) and other wild pollinators, which together help support agricultural economies and international food supplies. Managed honey bees represent a substantial fraction of total pollinators and are an important reservoir of enzootic pathogens that can affect disease epidemiology in various animal communities. To address this issue, beekeepers frequently administer antibiotics to their hives in an attempt to prevent or reduce disease occurrence and control intraspecies pathogen transmission bet when nearby apiaries.

Oxytetracycline (OTC), tylosin, and fumagillin are the most commonly used antibiotics in apiculture. Tetracycline-based agents are of particular concern given their extensive usage in human medicine and as bacteriostatic feed additives in livestock. Though indispensable under certain circumstances, overuse of tetracyclines pollutes the environment and inadvertently leads to the accumulation of antibiotic-resistance genes in many bacteria, including a multitude of pathogens relevant to human and honey bee health. Antibiotic exposure can also negatively impact key symbiotic bacteria within the microbiota (community of microorganisms residing on or within a multicellular organism) of honey bees. This compromises overall health status in hives as the distinct microbiota in healthy bees is crucial to host metabolic competency, immune regulation, growth and development, and resistance towards parasites and pathogens.

In many parts of the world, prophylactic usage of OTC is recommended under best management practices for beekeepers in the prevention of foulbrood diseases caused by Paenibacillus larvae and Melissococcus plutonius. In the case of P. larvae, which causes American foulbrood (AFB), there have been reports of widespread tetracycline resistance occurring since the early 2000’s. Identical sequence homology of tetracycline-resistance loci found in P. larvae and core members of the honey bee microbiota suggests that there is horizontal gene transfer bet theyen commensals and pathogens via mobile genetic elements such as transposons and plasmids. Importantly, despite susceptibility or resistance, OTC is unable to treat P. larvae spores in the comb, which can act as a source of reinfection. To address these issues and guard against the potentially rapid evolution of resistance, it is prudent to test alternative control measures, which so far include hygienic breeding, use of bioactive essential oils, bacteriophage therapy, synthetic indoles with anti-germination properties, and supplementation of hives with lactic acid bacteria. The promise of this latter approach is up-held by studies demonstrating that lactobacilli can promote insect innate immunity and detoxification , extend longevity of adult honey bees, and stimulate queen brood production.

In our previous work,  they demonstrated that pollen patty hive supplements infused with three select strains of lactobacilli (Lactobacillus rhamnosus GR-1, Lactobacillus plantarum Lp39, and Lactobacillus kunkeei BR-1; LX3) could reduce P. larvae loads in honey bee hives experiencing active AFB outbreak and improve honey bee survival towards P. larvae infection in vitro. Here,  they evaluated OTC treatment efficacy in subclinically infected hives and characterized how routine exposure to this common antibiotic impacts immune and microbiota dynamics in honey bees. In addition, they evaluated how treatment augmentation with LX3 following OTC exposure influences antibiotic recovery rates as evaluated by immune functionality, microbial homeostasis, and hive productivity.

For complete details: https://www.nature.com/articles/s42003-020-01259-8

Regards,

Jessica

Managing editor

International journal of pure and applied zoology