Fumagillin efficacy against Nosema ceranae and mixed N. ceranae and Nosema apis colony infections after fall treatment in western Canada

Tuesday, November 15, 2022

2:42 PM – 2:54 PM PT

Location: Vancouver Convention Centre, Meeting Room 206

Presenting Author(s)

Sarah Biganski

Postdoctoral Fellow
University of Saskatchewan
Saskatoon, Saskatchewan, Canada

Co-Author(s)

Midhun Sebastian Jose

Postdoctoral Fellow
University of Saskatchewan
Saskatoon, Saskatchewan, Canada
Muhammad Fahim Raza

postdoctoral fellow
University of Saskatchewan
Saskatoon, Saskatchewan, Canada
OO

Oleksii Obshta

University of Saskatchewan
Saskatoon, Saskatchewan, Canada
IM

Igor Moshynskyy

University of Saskatchewan
Saskatoon, Saskatchewan, Canada
IK

Ivanna Kozii

University of Saskatchewan
Saskatoon, Saskatchewan, Canada
RK

Roman Koziy

University of Saskatchewan
Saskatoon, Saskatchewan, Canada
MZ

Michael Zabrodski

University of Saskatchewan
Saskatoon, Saskatchewan, Canada
Sarah Wood

Research Chair in Pollinator Health and Associate Professor
University of Saskatchewan
Saskatoon, Saskatchewan, Canada
ES

Elemir Simko

University of Saskatchewan
Saskatoon, Saskatchewan, Canada

Nosemosis is an intestinal disorder of adult honey bees caused by the fungal pathogens Nosema apis and Nosema ceranae. The antibiotic fumagillin is registered in Canada for treatment to prevent high overwinter colony mortalities. However, the recommended dosage is still based on efficacy studies for N. apis, the native pathogen in the European honey bee. With spillover from the Asian honey bee, the invasive N. ceranae became more prevalent in managed European honey bees and seem to replace N. apis due to yet unknown reasons. From summer 2021 to spring 2022, we performed a comprehensive colony study to test the hypothesis if Nosema spp. ratio may shift after fumagillin fall treatment. Furthermore, we examined the influence of fall treatment on colony strength, productivity, overwintering survival, spring infection levels, and potential correlation of Varroa destructor infestation with Nosema colony infection. Our study consisted of a fumagillin treatment group and a non-treatment group with each nine N. ceranae-infected, mixed-infected, and non-infected colonies. Colonies were assigned to infection or non-infection groups by repeated spore counts in summer based on 60 pooled bees per colony, and multiplex qPCR. Bees were collected pre- and post-treatment, and in spring. Our preliminary results suggest fumagillin efficiently reduced the overall spore load post-treatment and in spring compared to non-treatment group but N. ceranae infections were not completely cleared with the recommended dosage. Furthermore, N. ceranae spore load increased faster in spring in previously mixed-infected colonies, potentially explaining its higher prevalence than N. apis in Canadian apiaries.