John Chmiel

John Chmiel
The University of Western Ontario | UWO · Department of Microbiology and Immunology

Master of Science

About

18
Publications
3,055
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
276
Citations
Featured research
Article
Full-text available
The concerns over honey bee health and colony collapse have led to an increased interest in the potential for beneficial bacteria as an intervention. However, the efficacy of this approach is mostly unknown because the application of bacterial adjuncts to hives has not often proceeded by understanding the strains being applied or how they function. This article summarizes the effects reported from published studies (2004–2020) that have experimentally tested the influence of beneficial bacteria, including probiotics, on honey bee immune function, pathogen resistance, or colony productivity. The meta-analysis shows that bacterial intervention can improve bee survival against American foulbrood and Nosema infection, and increase honey yields, but the underlying molecular correlates remain poorly understood. There is some evidence that honey bee–derived bacteria could be superior to exogenous bacterial species, although further evaluation is needed. We advocate for a more organized and transparent approach that includes the rationale for strain choice and delivery, a thorough description of treatment formulations, viable counts and their application to hives, and improved design of experimental field trials to consistently include controls and other features that allow interpretation of results. Successful studies should also be validated for efficacy and reproducibility.
Article
Full-text available
Managed populations of the European honey bee (Apis mellifera) support the production of a global food supply. This important role in modern agriculture has rendered honey bees vulnerable to the noxious effects of anthropogenic stressors such as pesticides. Although the deleterious outcomes of lethal pesticide exposure on honey bee health and performance are apparent, the ominous role of sublethal pesticide exposure is an emerging concern as well. Here, we use a data harvesting approach to better understand the toxicological effects of pesticide exposure across the honey bee life cycle. Through compiling adult- and larval-specific median lethal dose (LD50) values from 93 published data sources, LD50 estimates for insecticides, herbicides, acaricides, and fungicides are highly variable across studies, especially for herbicides and fungicides, which are underrepresented in the meta-data set. Alongside major discrepancies in these reported values, further examination of the compiled data suggested that LD50 may not be an ideal metric for honey bee risk assessment. We also discuss how sublethal effects of pesticide exposure, which are not typically measured in LD50 studies, can diminish honey bee reproduction, immunity, cognition, and overall physiological functioning, leading to suboptimal honey bee performance and population reduction. In consideration of actionable solutions to mitigate the effects of sublethal pesticide exposure, we have identified the potential for probiotic supplementation as a promising strategy that can be easily incorporated alongside current agricultural infrastructure and apicultural management practices. Probiotic supplementation is regularly employed in apiculture but the potential for evidence-based targeted approaches has not yet been fully explored within a formal toxicological context. We discuss the benefits, practical considerations, and limitations for the use and delivery of probiotics to hives. Ultimately, by subverting the sublethal effects of pesticides we can help improve the long-term survival of these critical pollinators.
Article
Full-text available
American foulbrood (AFB) is a highly virulent disease afflicting honey bees (Apis mellifera). The causative organism, Paenibacillus larvae, attacks honey bee brood and renders entire hives dysfunctional during active disease states, but more commonly resides in hives asymptomatically as inactive spores that elude even vigilant beekeepers. The mechanism of this pathogenic transition is not fully understood, and no cure exists for AFB. Here, we evaluated how hive supplementation with probiotic lactobacilli (delivered through a nutrient patty; BioPatty) affected colony resistance towards a naturally occurring AFB outbreak. Results demonstrated a significantly lower pathogen load and proteolytic activity of honey bee larvae from BioPatty-treated hives. Interestingly, a distinctive shift in the microbiota composition of adult nurse bees occurred irrespective of treatment group during the monitoring period, but only vehicle-supplemented nurse bees exhibited higher P. larvae loads. In vitro experiments utilizing laboratory-reared honey bee larvae showed Lactobacillus plantarum Lp39, Lactobacillus rhamnosus GR-1, and Lactobacillus kunkeei BR-1 (contained in the BioPatty) could reduce pathogen load, upregulate expression of key immune genes, and improve survival during P. larvae infection. These findings suggest the usage of a lactobacilli-containing hive supplement, which is practical and affordable for beekeepers, may be effective for reducing enzootic pathogen-related hive losses.
Article
Full-text available
Sublethal exposure to certain pesticides (e.g., neonicotinoid insecticides) is suspected to contribute to honey bee ( Apis mellifera ) population decline in North America. Neonicotinoids are known to interfere with immune pathways in the gut of insects, but the underlying mechanisms remain elusive. We used a Drosophila melanogaster model to understand how imidacloprid (a common neonicotinoid) interferes with two innate immune pathways—Duox and Imd. We found that imidacloprid dysregulates these pathways to reduce hydrogen peroxide production, ultimately leading to a dysbiotic shift in the gut microbiota. Intriguingly, we found that presupplementation with probiotic bacteria could mitigate the harmful effects of imidacloprid. Thus, these observations uncover a novel mechanism of pesticide-induced immunosuppression that exploits the interconnectedness of two important insect immune pathways.
Additional affiliations
September 2018 - December 2018
The University of Western Ontario
Position
  • Graduate Teaching Assistant
Education
September 2017 - July 2020
The University of Western Ontario
Field of study
  • Microbiology & Immunology
September 2014 - May 2018
The University of Western Ontario
Field of study
  • Microbiology & Immunology

Publications

Publications (13)
Article
Full-text available
Sublethal exposure to certain pesticides (e.g., neonicotinoid insecticides) is suspected to contribute to honey bee ( Apis mellifera ) population decline in North America. Neonicotinoids are known to interfere with immune pathways in the gut of insects, but the underlying mechanisms remain elusive. We used a Drosophila melanogaster model to underst...
Article
Full-text available
American foulbrood (AFB) is a highly virulent disease afflicting honey bees (Apis mellifera). The causative organism, Paenibacillus larvae, attacks honey bee brood and renders entire hives dysfunctional during active disease states, but more commonly resides in hives asymptomatically as inactive spores that elude even vigilant beekeepers. The mecha...
Article
Full-text available
Managed populations of the European honey bee (Apis mellifera) support the production of a global food supply. This important role in modern agriculture has rendered honey bees vulnerable to the noxious effects of anthropogenic stressors such as pesticides. Although the deleterious outcomes of lethal pesticide exposure on honey bee health and perfo...
Article
Full-text available
The concerns over honey bee health and colony collapse have led to an increased interest in the potential for beneficial bacteria as an intervention. However, the efficacy of this approach is mostly unknown because the application of bacterial adjuncts to hives has not often proceeded by understanding the strains being applied or how they function....
Article
Objective: Kidney stones are a common medical condition that is increasing in prevalence worldwide. Approximately, ∼80% of urinary calculi are composed of calcium oxalate (CaOx). There is a growing interest toward identifying therapeutic compounds that can inhibit the formation of CaOx crystals. However, some chemicals (e.g., antibiotics and bacte...
Article
Full-text available
Lactobacillus crispatus is the dominant species in the vagina of many women. With the potential for strains of this species to be used as a probiotic to help prevent and treat dysbiosis, we investigated isolates from vaginal swabs with Lactobacillus-dominated and a dysbiotic microbiota. A comparative genome analysis led to the identification of met...
Article
Full-text available
Widespread antibiotic usage in apiculture contributes substantially to the global dissemination of antimicrobial resistance and has the potential to negatively influence bacterial symbionts of honey bees (Apis mellifera). Here, we show that routine antibiotic administration with oxytetracycline selectively increased tetB (efflux pump resistance gen...
Article
Full-text available
Abiraterone acetate (AA) is an inhibitor of androgen biosynthesis, though this cannot fully explain its efficacy against androgen-independent prostate cancer. Here, we demonstrate that androgen deprivation therapy depletes androgen-utilizing Corynebacterium spp. in pros-tate cancer patients and that oral AA further enriches for the health-associate...
Article
Pesticide exposure, infectious disease, and nutritional stress contribute to honey bee mortality and a high rate of colony loss. This realization has fueled a decades-long investigation into the single and combined effects of each stressor and their overall bearing on insect physiology. However, one element largely missing from this research effort...
Article
Full-text available
Heavy metals are highly toxic elements that contaminate the global food supply and affect human and wildlife health. Purification technologies are often too expensive or not practically applicable for large-scale implementation, especially in impoverished nations where heavy metal contamination is widespread. Lactobacillus rhamnosus GR-1 (LGR-1) wa...

Network

Cited By