With generous support from key donors, the Western College of Veterinary Medicine (WCVM) established the Pollinator Health Research Chair at the University of Saskatchewan (USask) in 2022. 

The new research chair's role is to investigate, enhance and promote the health of pollinators, both managed and wild — including honey bees and wild bees. 

As a tenure-track WCVM faculty member, the Pollinator Health Research Chair conducts interdisciplinary and collaborative research that focuses on issues affecting pollinator health.

The chair builds on the strengths of the college's existing honey bee health research group, which is based in the WCVM's Department of Veterinary Pathology. Led by Dr. Elemir Simko, the WCVM was the first veterinary college in North America to establish a honey bee research and teaching program in 2015. 


Our Chair

Dr. Sarah Wood
Dr. Sarah Wood, USask Pollinator Health Research Chair at the WCVM.

Dr. Sarah Wood (MSc, DVM, PhD, Dipl. ACVP) holds the position of USask Pollinator Health Research Chair at the Western College of Veterinary Medicine (WCVM). She is also an associate professor in the WCVM's Department of Veterinary Pathology and is board certified with the American College of Veterinary Pathologists (ACVP). 

Wood is a USask alumna who earned Doctor of Veterinary Medicine (DVM) and PhD degrees from the WCVM, and she has worked on research related to pollinator health since 2015.

Wood's research interests include infectious diseases of honey bees, pesticide risk assessment for pollinators, quantifying pollinator contributions to agricultural productivity, and developing honey bees as experimental models for human and animal disease. 

“My long-term vision for this research chair position is to enhance agricultural sustainability and ecosystem health by studying managed and wild bee species from a veterinary perspective. By applying veterinary research tools to address the ongoing challenges to pollinator health and biodiversity, I think we can make impactful change,” says Wood.


The Western College of Veterinary Medicine (WCVM) sincerely thanks the following organizations for their generous support of the Pollinator Health Research Chair's creation. View donor page. 


Click on the Sway presentation (above) to learn more about the people who are part of the WCVM's honey bee health research group as well as the research team's pollinator health research projects. This presentation is best viewed in full screen mode. 


Members of the WCVM Honey Bee Health Research Group 
Current members


Past members

Colby Klein Effects of pesticides on drone reproductive fitness
Michael Zabrodski Risk assessment of American foulbrood disease in honey
Roman Koziy Deformed wing virus
Igor Medici Nosemosis and probiotics
Mohen Sharafi American foulbrood and cryopreservation of drone sperm
Sophie Derveau Pesticides and drones

Visiting scientists and students

Ihor Dvylyuk In vitro model of European foulbrood disease
Juliana Lunardi Larval infection by Nosema
Roney m. Silva Effects of neonicotinoids on winter bees

Summer research undergraduate students

Vanessa Brown In vivo model of European foulbrood disease
Tessa Lester Enhanced diagnosis for osimosis
Breanne Bevelander Honey bee model for fetal alcohol syndrome in children
Olena Simko Honey bee model for fetal alcohol syndrome in children
Lara Reitsma What happens to P. larvae spores after cessation of antibiotic use in honey bee hives?
Mateo C. Ospina Risk assessment of American foulbrood in honey bee colony
Brandele Brown Does blueberry pollen increase the susceptibility of honey bees to European foulbrood disease? 
Allyssa Cloet Do highly pathogenic isolates of M. plutonius explain outbreaks of EFB during blueberry pollination?
Melanie Roulin Does blueberry pollen predispose honey bees to European foulbrood disease?
Jessica DeBruyne Determining risk for American foulbrood disease in Saskatchewan beekeeping operations
Dana Liebe European foulbrood disease: comparison between Saskatchewan and British Columbia honey bee operations
Jocelyne Chalifour Do pesticides make honey bee larvae more susceptible to European foulbrood disease?
Sarah Barnsley Which honey bee caste is most sensitive to pesticide exposure?
Marina B. da Silva Effects of thiamethoxam on honey bee queens
Alexandra Wentzell Investigation of outbreaks of American foulbrood disease in Saskatchewan
Crystani Folkes Effects of thiamethoxam on developing honey bee workers
Colby Klein Effects of neonicotinoids on honey bee drones
Leland Guillemin Evaluation of sperm of drones
Claudia O. Fabela Effects of thiamethoxam on developing honey bee queens
Esther Derksen Effects of neonicotinoids on honey bee larvae
Claire Janse van Rensburg Do honey bees really prefer food containing neonicotinoid pesticides?
Maddy Friesen Effects of thiamethoxam on the establishment of honey bee colonies from New Zealand package bees


Zabrodski MW, Epp T, Wilson G, Moshynskyy I, Sharafi M, Reitsma L, Castano Ospina M, DeBruyne JE, Wentzell A, Wood SC, Kozii IV, Klein CD, Thebeau J, Sobchishin L, Ruzzini AC, Simko E. "Establishment of apiary-level risk of American foulbrood through the detection of Paenibacillus larvae spores in pooled, extracted honey in Saskatchewan." Scientific Reports. 2022 May 25;12(1):8848. doi: 10.1038/s41598-022-12856-4


Paenibacillus larvae, the causative agent of American foulbrood (AFB), produces spores that may be detectable within honey. We analyzed the spore content of pooled, extracted honey from 52 large-scale (L) and 64 small-scale (S) Saskatchewan beekeepers over a two-year period (2019–2020). Our objectives were: (i) establish reliable prognostic reference ranges for spore concentrations in extracted honey to determine future AFB risk at the apiary level; (ii) identify management practices as targets for mitigation of risk. P. larvae spores were detected in 753 of 1476 samples (51%). Beekeepers were stratified into low (< 2 spores/gram), moderate (2- < 100 spores/gram), and high (≥ 100 spores/gram) risk categories. Of forty-nine L beekeepers sampled in 2019, those that reported AFB in 2020 included 0/26 low, 3/18 moderate, and 3/5 high risk. Of twenty-seven L beekeepers sampled in 2020, those that reported AFB in 2021 included 0/11 low, 2/14 moderate, and 1/2 high risk. Predictive modelling included indoor overwintering of hives, purchase of used equipment, movement of honey-producing colonies between apiaries, beekeeper demographic, and antimicrobial use as risk category predictors. Saskatchewan beekeepers with fewer than 2 spores/gram in extracted honey that avoid high risk activities may be considered at low risk of AFB the following year.

Masood, F., Thebeau, J.M., Cloet, A. et al. Evaluating approved and alternative treatments against an oxytetracycline-resistant bacterium responsible for European foulbrood disease in honey bees. Sci Rep 12, 5906 (2022). https://doi.org/10.1038/s41598-022-09796-4

European foulbrood (EFB) is a disease of honey bee larvae caused by Melissococcus plutonius. In North America, oxytetracycline (OTC) is approved to combat EFB disease though tylosin (TYL) and lincomycin (LMC) are also registered for use against American foulbrood disease. Herein, we report and characterize an OTC-resistant M. plutonius isolate from British Columbia, Canada, providing an antimicrobial sensitivity to the three approved antibiotics and studying their abilities to alter larval survival in an in vitro infection model. Specifically, we investigated OTC, TYL, and LMC as potential treatment options for EFB disease using laboratory-reared larvae infected with M. plutonius. The utility of the three antibiotics were compared through an experimental design that either mimicked metaphylaxis or antimicrobial intervention. At varying concentrations, all three antibiotics prevented clinical signs of EFB disease following infection with M. plutonius 2019BC1 in vitro. This included treatment with 100 μg/mL of OTC, a concentration that was ~ 3× the minimum inhibitory concentration measured to inhibit the strain in nutrient broth. Additionally, we noted high larval mortality in groups treated with doses of OTC corresponding to ~ 30× the dose required to eliminate bacterial growth in vitro. In contrast, TYL and LMC were not toxic to larvae at concentrations that exceed field use. As we continue to investigate antimicrobial resistance (AMR) profiles of M. plutonius from known EFB outbreaks, we expect a range of AMR phenotypes, reiterating the importance of expanding current therapeutic options along with alternative management practices to suppress this disease.

Zabrodski MW, DeBruyne JE, Wilson G, Moshynskyy I, Sharafi M, Wood SC, Kozii IV, Thebeau J, Klein CD, Medici de Mattos I, Sobchishin L, Epp T, Ruzzini AC, Simko E. "Comparison of individual hive and apiary-level sample types for spores of Paenibacillus larvae in Saskatchewan honey bee operations." PLoS One. 2022 Feb 7;17(2):e0263602. doi: 10.1371/journal.pone.0263602


Three commercial honey bee operations in Saskatchewan, Canada, with outbreaks of American foulbrood (AFB) and recent or ongoing metaphylactic antibiotic use were intensively sampled to detect spores of Paenibacillus larvae during the summer of 2019. Here, we compared spore concentrations in different sample types within individual hives, assessed the surrogacy potential of honey collected from honey supers in place of brood chamber honey or adult bees within hives, and evaluated the ability of pooled, extracted honey to predict the degree of spore contamination identified through individual hive testing. Samples of honey and bees from hives within apiaries with a recent, confirmed case of AFB in a single hive (index apiaries) and apiaries without clinical evidence of AFB (unaffected apiaries), as well as pooled, apiary-level honey samples from end-of-season extraction, were collected and cultured to detect and enumerate spores. Only a few hives were heavily contaminated by spores in any given apiary. All operations were different from one another with regard to both the overall degree of spore contamination across apiaries and the distribution of spores between index apiaries and unaffected apiaries. Within operations, individual hive spore concentrations in unaffected apiaries were significantly different from index apiaries in the brood chamber (BC) honey, honey super (HS) honey, and BC bees of one of three operations. Across all operations, BC honey was best for discriminating index apiaries from unaffected apiaries (p = 0.001), followed by HS honey (p = 0.06), and BC bees (p = 0.398). HS honey positively correlated with both BC honey (rs = 0.76, p < 0.0001) and bees (rs = 0.50, p < 0.0001) and may be useful as a surrogate for either. Spore concentrations in pooled, extracted honey seem to have predictive potential for overall spore contamination within each operation and may have prognostic value in assessing the risk of future AFB outbreaks at the apiary (or operation) level.

Kozii IK, Wood SC, Koziy RV, Simko E. 2022. "Histomorphological description of the reproductive system in mated honey bee queens." Journal of Apicultural Research, 61:1, 114-126, DOI: 10.1080/00218839.2021.1900636

The accelerating decline of pollinator populations has become increasingly concerning in the last two decades. Honey bees are economically important pollinators and a model species to evaluate pollinator health. The decline in queen quality is one of the frequently reported causes associated with honey bee losses worldwide. Histopathology is an essential tool used for diagnostics and research in mammalian species and may provide insight into the histomorphological basis of a decline in queen quality. Thus, the purpose of this study was to summarize the previously described normal morphology of the entire reproductive tract of mated honey bee queens and to illustrate it by high quality photomicrographs. Accordingly, reproductive tracts of one-year old mated honey bee queens were processed for histology, serially sectioned, stained with hematoxylin and eosin, and used for the capture of high quality histological photomicrographs of the entire reproductive tract. This study illustrates the microscopic morphology of the queen reproductive tract which may facilitate further investigations of the cause and pathogenesis of the recent decline in reproductive fitness of honey bees using histopathology.

Kozii IV, Barnsley S, Silva MCBD, Wood SC, Klein CD, de Mattos IM, Zabrodski MW, Silva RCM, Fabela CIO, Guillemin L, Dvylyuk I, Ferrari MCO, Simko E. "Reproductive fitness of honey bee queens exposed to thiamethoxam during development." Veterinary Pathology. 2021 Nov;58(6):1107-1118. doi: 10.1177/03009858211031845. Epub 2021 Jul 16. 


The productivity and survival of honey bee (Apis mellifera) colonies depend on queen bee health. Colony-level neonicotinoid exposure has negative effects on reproductive fitness of honey bee queens. However, it is unclear if the observed effects are a direct outcome of neonicotinoid toxicity or result from suboptimal care of developing queens by exposed workers. The aim of this study was to evaluate larval survival, reproductive fitness, and histopathology of honey bee queens exposed to incremental doses (0, 5, 50 ng) of the neonicotinoid thiamethoxam (THI) applied directly to individual late larvae (7 days post-oviposition) of queens. The 5 ng dose represents a calculated high environmental level of exposure for honey bee queen larvae. Morphometric evaluation revealed that the total area of mandibular gland epithelium in queens exposed to 5 and 50 ng THI was reduced by 14% (P = .12) and 25% (P = .001), respectively. Decreased mandibular gland size may alter pheromone production, which could in part explain previously observed negative effects of THI on the reproductive fitness of queens. We also found that late larval exposure to THI reduced larval and pupal survival and decreased sperm viability in mated queens. These changes may interfere with queen development and reproductive longevity.

Klein CD, Kozii IV, Wood SC, Koziy RV, Zabrodski MW, Dvylyuk I, de Mattos IM, Moshynskyy I, Honaramooz A, Simko E. "Testicular changes of honey bee drones, Apis mellifera (Hymenoptera: Apidae), during sexual maturation." Journal of Insect Science. 2021 Nov 1;21(6):3. doi: 10.1093/jisesa/ieab049


The normal developmental anatomy and histology of the reproductive tract of the honey bee drone, Apis mellifera (Linnaeus, 1758), has been well documented. The post-emergence maturation changes of the accessory glands are likewise well understood, but the normal histological changes of the testicle undergoing physiologic atrophy are not well characterized. To address this knowledge gap, herein we describe the anatomy and sequential histological stages of normal testicular atrophy of drones sampled daily from emergence to sexual maturity in the spring (June) and early summer (July). Testicular histological changes during maturation are characterized by the following stages: I) conclusion of spermiogenesis; II) evacuation of spermatodesms from tubular lumens; III) progressive follicular cell atrophy, and IV) complete atrophy and collapse of testicular parenchyma. Tubular changes occur in a basilar to apical direction where segments closer to the vas deferens are histologically more mature than corresponding apical segments. In addition, the rate of testicular maturation was found to change with seasonal progression. This description of physiologic testicular atrophy should be useful for future studies investigating potential pathological effects of stressors on drone testes during sexual maturation.

Wood SC, Chalifour JC, Kozii IV, Medici de Mattos I, Klein CD, Zabrodski MW, Moshynskyy I, Guarna MM, Wolf Veiga P, Epp T, Simko E. "In vitro effects of pesticides on European foulbrood in honeybee larvae." Insects. 2020 Apr 17;11(4):252. doi: 10.3390/insects11040252


Neonicotinoid and fungicide exposure has been linked to immunosuppression and increased susceptibility to disease in honeybees (Apis mellifera). European foulbrood, caused by the bacterium Melissococcus plutonius, is a disease of honeybee larvae which causes economic hardship for commercial beekeepers, in particular those whose colonies pollinate blueberries. We report for the first time in Canada, an atypical variant of M. plutonius isolated from a blueberry-pollinating colony. With this isolate, we used an in vitro larval infection system to study the effects of pesticide exposure on the development of European foulbrood disease. Pesticide doses tested were excessive (thiamethoxam and pyrimethanil) or maximal field-relevant (propiconazole and boscalid). We found that chronic exposure to the combination of thiamethoxam and propiconazole significantly decreased the survival of larvae infected with M. plutonius, while larvae chronically exposed to thiamethoxam and/or boscalid or pyrimethanil did not experience significant increases in mortality from M. plutonius infection in vitro. Based on these results, individual, calculated field-realistic residues of thiamethoxam and/or boscalid or pyrimethanil are unlikely to increase mortality from European foulbrood disease in honeybee worker brood, while the effects of field-relevant exposure to thiamethoxam and propiconazole on larval mortality from European foulbrood warrant further study.


Zabrodski MW, Wilson G, Moshynskyy I, Wentzell A, Wood SC, Klein CD, Kozii IV, de Mattos IM, Epp T, Simko E. "Investigation of clinical outbreaks of American foulbrood in honey-bee operations in Saskatchewan." Canadian Veterinary Journal. 2020 Oct;61(10):1055-1059. PMID: 33012819; PMCID: PMC7488369.


Four outbreaks of American foulbrood were investigated in honey-bee operations in Saskatchewan during the summer of 2019. Clinical signs were confirmed by the Saskatchewan Provincial Specialist in Apiculture and the causative agent was cultured and identified through matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Evaluation of management practices revealed off-label metaphylactic use of oxytetracycline in 3 of 4 operations and a discontinuation of antibiotic use in the fourth. Recent regulatory changes regarding access to medically important antimicrobials has provided an opportunity for veterinarians to promote evidence-based use of antimicrobials in apiculture while safe-guarding the health of commercial honeybee populations and the economic viability of their producers.

Wood SC, de Mattos IM, Kozii IV, Klein CD, Dvylyuk I, Folkes CDA, de Carvalho Macedo Silva R, Moshynskyy I, Epp T, Simko E. 2020. "Effects of chronic dietary thiamethoxam and prothioconazole exposure on Apis mellifera worker adults and brood." Pest. Manag. Sci., 76: 85-94. https://doi.org/10.1002/ps.5501


Chronic exposure of honey bees (Apis mellifera Linnaeus) to the neonicotinoid thiamethoxam and the fungicide prothioconazole is common during foraging in agricultural landscapes. We evaluated the survival and hypopharyngeal gland development of adult worker honey bees, and the survival of the worker brood when chronically exposed to thiamethoxam or thiamethoxam and prothioconazole in combination.


We found that 30 days of exposure to 40 μg kg–1 of thiamethoxam significantly (P < 0.001) increased the frequency of death in worker adults by four times relative to solvent control. The worker brood required 23 times higher doses of thiamethoxam (1 mg L–1 or 909 μg kg–1) before a significant (P = 0.04), 3.9 times increase in frequency of death was observed relative to solvent control. No additive effects of simultaneous exposure of worker adults or brood to thiamethoxam and prothioconazole were observed. At day 8 and day 12, the hypopharyngeal gland acinar diameter was not significantly different (P > 0.05) between controls and adult workers exposed to thiamethoxam and/or prothioconazole.


These results indicate that chronic exposure to field-realistic doses of thiamethoxam and/or prothioconazole are unlikely to affect the survival of adult workers and brood.

Koziy RV, Wood SC, Kozii IV, van Rensburg CJ, Moshynskyy I, Dvylyuk I, Simko E. "Deformed wing virus infection in honey bees (Apis mellifera L.)." Vet Pathol. 2019 Jul;56(4):636-641. doi: 10.1177/0300985819834617. Epub 2019 Mar 11. PMID: 30857499.

Deformed wing virus (DWV) is a single-stranded RNA virus of honey bees (Apis mellifera L.) transmitted by the parasitic mite Varroa destructor. Although DWV represents a major threat to honey bee health worldwide, the pathological basis of DWV infection is not well documented. The objective of this study was to investigate clinicopathological and histological aspects of natural DWV infection in honey bee workers. Emergence of worker honey bees was observed in 5 colonies that were clinically affected with DWV and the newly emerged bees were collected for histopathology. DWV-affected bees were 2 times slower to emerge and had 30% higher mortality compared to clinically normal bees. Hypopharyngeal glands in bees with DWV were hypoplastic, with fewer intracytoplasmic secretory vesicles; cells affected by apoptosis were observed more frequently. Mandibular glands were hypoplastic and were lined by cuboidal epithelium in severely affected bees compared to tall columnar epithelium in nonaffected bees. The DWV load was on average 1.7 × 106 times higher (P < .001) in the severely affected workers compared to aged-matched sister honey bee workers that were not affected by deformed wing disease based on gross examination. Thus, DWV infection is associated with prolonged emergence, increased mortality during emergence, and hypoplasia of hypopharyngeal and mandibular glands in newly emerged worker honey bees in addition to previously reported deformed wing abnormalities.

Wood SC, Kozii IV, Medici de Mattos I, de Carvalho Macedo Silva R, Klein CD, Dvylyuk I, Moshynskyy I, Epp T, Simko E. "Chronic high-dose neonicotinoid exposure decreases overwinter survival of Apis mellifera L." Insects. 2019 Dec 31;11(1):30. doi: 10.3390/insects11010030


Overwinter colony mortality is an ongoing challenge for North American beekeepers. During winter, honey bee colonies rely on stored honey and beebread, which is frequently contaminated with the neonicotinoid insecticides clothianidin and thiamethoxam. To determine whether neonicotinoid exposure affects overwinter survival of Apis mellifera L., we chronically exposed overwintering field colonies and winter workers in the laboratory to thiamethoxam or clothianidin at different concentrations and monitored survival and feed consumption. We also investigated the sublethal effects of chronic thiamethoxam exposure on colony pathogen load, queen quality, and colony temperature regulation. Under field conditions, high doses of thiamethoxam significantly increased overwinter mortality compared to controls, with field-realistic doses of thiamethoxam showing no significant effect on colony overwinter survival. Under laboratory conditions, chronic neonicotinoid exposure significantly decreased survival of winter workers relative to negative control at all doses tested. Chronic high-dose thiamethoxam exposure was not shown to impact pathogen load or queen quality, and field-realistic concentrations of thiamethoxam did not affect colony temperature homeostasis. Taken together, these results demonstrate that chronic environmental neonicotinoid exposure significantly decreases survival of winter workers in the laboratory, but only chronic high-dose thiamethoxam significantly decreases overwinter survival of colonies in the field.

Wood SC, Kozii IV, Koziy RV, Epp T, Simko E. "Comparative chronic toxicity of three neonicotinoids on New Zealand packaged honey bees." PLoS One. 2018 Jan 2;13(1):e0190517. doi: 10.1371/journal.pone.0190517



Thiamethoxam, clothianidin, and imidacloprid are the most commonly used neonicotinoid insecticides on the Canadian prairies. There is widespread contamination of nectar and pollen with neonicotinoids, at concentrations which are sublethal for honey bees (Apis mellifera Linnaeus).


We compared the effects of chronic, sublethal exposure to the three most commonly used neonicotinoids on honey bee colonies established from New Zealand packaged bees using colony weight gain, brood area, and population size as measures of colony performance.


From May 7 to July 29, 2016 (12 weeks), sixty-eight colonies received weekly feedings of sugar syrup and pollen patties containing 0 nM, 20 nM (median environmental dose), or 80 nM (high environmental dose) of one of three neonicotinoids (thiamethoxam, clothianidin, and imidacloprid). Colonies were weighed at three-week intervals. Brood area and population size were determined from digital images of colonies at week 12. Statistical analyses were performed by ANOVA and mixed models.


There was a significant negative effect (-30%, p<0.01) on colony weight gain (honey production) after 9 and 12 weeks of exposure to 80 nM of thiamethoxam, clothianidin, or imidacloprid and on bee cluster size (-21%, p<0.05) after 12 weeks. Analysis of brood area and number of adult bees lacked adequate (>80%) statistical power to detect an effect.


Chronic exposure of honey bees to high environmental doses of neonicotinoids has negative effects on honey production. Brood area appears to be less sensitive to detect sublethal effects of neonicotinoids.


Pollinator health-related news at the WCVM



Dr. Sarah Wood
USask Pollinator Health Research Chair

Dr. Elemir Simko, Professor
Department of Veterinary Pathology