Probiotics beyond human health: Honey bees, environmental toxins, and food security.

Honey bee obtaining nectar from a flower. Photo credit: Andrew Pitek.

By Brendan Daisley

Growing up, I was always a fan of comic book heroes and intrigued by the potential to develop super powers via the bite or sting of an insect. So, you can imagine my dismay when being stung in the ear by a bee at age 7 left me looking half ready to join a circus (think child Dumbo) but, alas, with no ability to fly. Looking back, I’m fairly certain I was stung by a wasp (Family: Vespidae) and the consequential resentment I held for years towards bees (Family: Apidae) was probably unwarranted. Notably though, and similar to most others who will read this, the thought of bees has been synonymously linked with honey in my head for as long as I can remember. Yet, for most of my life I never once considered bees when consuming some of my other favourite foods such as apples, blueberries, strawberries, grapefruit, peaches, carrots, cucumbers, almonds, or peanuts – all of which are heavily dependent upon pollination by these insects. Specifically, it’s estimated that honey bees (Apis mellifera) alone are crucial to the production of over one third of the global food supply and that they contribute greatly to agricultural economies.

The problem is that bee populations are steadily declining due to pesticide exposure, infectious disease, and habitat loss. Despite the common preference of grouping these as separate issues, in reality they are not mutually exclusive and can synergistically influence the health of honey bees.

Dr. Gregor Reid, probiotic expert who would like to help save the bees.

Several years ago, the Reid lab (Western University, Canada) initiated an effort to tackle this problem using probiotics. Seems crazy? At first glance many of Gregor’s ideas are, however, as it turns out there is a surprising amount of merit to this approach. Early work on the project by Mark Trinder (now University of British Columbia) demonstrated that certain strains of Lactobacillus rhamnosus could help reduce toxicity of chlorpyrifos and parathion (two common pesticides) and improve survival in Drosophila melanogaster (1,2) (an established honey bee model). Using this same high-throughput model system, we also discovered the potential of certain lactobacilli strains to mitigate the effects of other important pesticides (like the controversial neonicotinoid, imidacloprid, which is banned in many countries) and reduce susceptibility to infection via beneficial immune stimulation (3,4). From this seminal work, a number of opportunities and collaborations have since emerged.

A fresh BioPatty containing beneficial nutrients and three Lactobacillus strains. (Each 250 g patty contains 28.5 g soy flour, 74.1 g granulated sucrose, 15.4 g debittered brewer’s yeast, 132.1 g of a 2:1 [w/v] simple sucrose-based syrup solution), plus 4 mL vehicle (0.01 M PBS) per patty, and infusion of L. plantarum 39. L. rhamnosus GR-1, and L. kunkeei BR-1.

Our strategy is simple: improve bee health using a targeted approach with bacteria possessing beneficial functions that minimize the impact of two major bee health risks: pesticide exposure and infectious disease. Accordingly, we have carefully selected strains of lactobacilli with probiotic potential and are now supplementing them to honey bee hives directly in the form of a BioPatty.

Teaming up with local bee expert Dr. Graham Thompson (Western University) in our most recent study (5), we tested the BioPatty in hives experiencing a natural outbreak of American foulbrood – a devastating and incurable bee disease caused by Paenibacillus larvae. It was exciting to discover that the BioPatty was able to significantly lower pathogen burden and disease severity. Unfortunately, de-construction of the hives was mandated under government policy due to the severity and contagiousness of the disease which made follow-up monitoring not possible. Nevertheless, in vitro infection assays using laboratory reared honey bee larvae showed that probiotic supplementation could significantly improve survival against P. larvae. We concluded based on further investigation that these pro-survival effects were likely facilitated through lactobacilli-mediated modulation of honey bee immunity as well as direct inhibition of the pathogen itself. These findings challenge the current dogma in beekeeping that standard antibiotic administration is the only functional preventive strategy for American foulbrood. Accordingly, we have now gone on to perform comparative-based studies in which we assess the efficacy of the BioPatty relative to standard antibiotic therapy and hope to publish these promising findings shortly.

LEft: Reid and Thompson labs on the opening day of our experimental apiary. Right: PhD Candidate, Brendan Daisley (Reid lab) not exactly dressed appropriately but taking amazing notes.

So, we’ve now shown that probiotics can help bees fight infection…but what about pesticide exposure?

Top: Bee team at UC Davis (Andrew Pitek, Robin Lowery, Dr. Elina Niño, Brendan Daisley). Bottom left: World Honey Bee Day 2019 with Seed (Jackie Nicole, Brendan Daisley, Jennie Ostendorf. Bottom middle: Bee team at UC Davis. Bottom right: Local bee art in Davis, California

Through actively engaging in science advocacy campaigns and networking with like-minded scientists, we’ve  helped to initiate several projects at different sites across North America aimed at determining whether the probiotics delivered in the BioPatty can help bees resist pesticides as well as other toxic air pollutants known to exist near places like Detroit. A collaboration with Bees in the D is ongoing.Our connection with Seed labs has led to testing our BioPatty on Californian bees in collaboration with applied honey bee research and extension expert, Dr. Elina Niño (University of California, Davis). In visiting the Niño lab last spring during project planning and set-up, I experienced first hand just how important honey bees are to the production of almonds in this region. Specifically, it’s estimated that 1.5 million honey bee hives are imported to California annually for purposes of almond crop pollination at a cost of over $300 million dollars. Unfortunately, approximately 80,000 of these hives are wiped out annually due to the combined effects of pesticide exposure and enzootic diseases.

Queen been Ara Katz (Seed Labs) on World Honey Bee Day 2019 highlighting actionable ways in which we can help the bees and also treat out planet better as a whole.

The overarching goal of this collaborative project is to test whether supplementation with probiotic lactobacilli possessing anti-pesticide and pro-immunity properties can help reduce colony loss in the honey bee-centric state. Beyond advancing the understanding of host-microbe interactions in the context of bee health under natural conditions, this research has tremendous potential to help beekeepers and farmers alike who heavily dependent upon the health of these insects.

We are not naive enough to think that probiotics alone will completely solve the problem of honey bee population decline. But, we hope it will be sufficient to tilt the scale in their favour. Importantly, we want people to think about how probiotics can be advantageous not only to human health, but also for the ecosystem. Ultimately, the goal is to shift the narrative away from using toxic substances that pollute the environment in favour of biofriendly options and encourage others to find a ‘path to relevance’ (6). Altogether, the coordinated efforts of scientists, beekeepers, and decision-makers on a global scale will be paramount in reversing the global decline of bee populations.

Obviously we have a long we to go as a community, but in completing my PhD in Microbiology and Immunology my goal is to demonstrate the rationale and mechanisms by which certain strains of lactobacilli can improve the health and productivity of an ecologically and economically important species – the honey bee. In doing so, I hope the findings from my research can be functionally applied in the real-world beekeeping setting.

Long may our fuzzy pollinator friends fly. 

Photo credit: Andrew Pitek

References

1. Trinder, M. et al. Probiotic Lactobacillus rhamnosus reduces organophosphate pesticide absorption and toxicity to Drosophila melanogaster. Appl. Environ. Microbiol. 82, 6204–6213 (2016).

2. Daisley, B. A. et al. Microbiota-mediated modulation of organophosphate insecticide toxicity by species-dependent lactobacilli interactions in a Drosophila melanogaster insect model. Appl. Environ. Microbiol. 84, e02820-17 (2018).

3. Daisley, B. A. et al. Neonicotinoid-induced pathogen susceptibility is mitigated by Lactobacillus plantarum immune stimulation in a Drosophila melanogaster model. Sci. Rep. 7, 2703 (2017).

4. Chmiel, J. A., Daisley, B. A., Burton, J. P. & Reid, G. Deleterious effects of neonicotinoid pesticides on Drosophila melanogaster immune pathways. mBio 10, (2019).

5. Daisley, B. A. et al. Novel probiotic approach to counter Paenibacillus larvae infection in honey bees. ISME J. (2019) doi:10.1038/s41396-019-0541-6.

6. Reid, G. Fourteen steps to relevance: taking probiotics from the bench to the consumer. Can. J. Microbiol. 66, 1–10 (2020).