Alberta Bee News
August 2021
Hive-side FAQ: Nosemosis By Emily Olson, Apiculture Technician, ABC Tech Transfer Program
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ith arrival of spring, honey bees can safely emerge from their insulated hives to meet the warming sun. Colonies are vulnerable and need plenty of resources to recoup the losses incurred over the winter months. Spring is an important time and high pathogen levels can hinder the progress of the colony. Specifically, Nosema disease is one to consider during this season. Nosema levels are typically highest during the spring and controlling this pathogen is critical to ensuring your colony thrives. WHAT IS NOSEMA? Nosemosis or Nosema disease is caused by a single celled fungi belonging to the phylum Microsporidia. Nosema reproduce by forming spores which can persist in the environment for many years. There are 2 species of Nosema that infect honey bees: Nosema apis and Nosema ceranae. Recently, these 2 species were reclassified to the genus Varimorpha but are still commonly referred to as Nosema. Originally, Nosema apis was a pest of the European honey bee (EHB) and Nosema ceranae, the Asian honey bee (AHB). However, N. ceranae crossed over to the EHB a few years ago and has become the dominant Nosema species found in our bees. Both species can be found within a single bee but it has been documented that N. ceranae is more detrimental to colonies. HOW DOES A COLONY BECOME INFECTED WITH NOSEMA? Queens, workers, and drones can become infected with Nosema spores by consuming contaminated food and water, during trophallaxis from an infected to a healthy bee, and by cleaning or robbing contaminated hives. After ingesting a Nosema spore, the fungus will germinate and multiply within the midgut cell, producing more spores and eventually rupturing the cell wall. The spores are released into the midgut and either infect other cells or are excreted. The fecal matter can then contaminate hive substrates (e.g., wax/comb) and infect other bees. HOW DOES NOSEMA AFFECT HONEY BEES? Nosema infection can cause long lasting digestion issues and lead to a reduced adult bee lifespan. Studies have shown that high number of Nosema spores are associated with malformation of brood-food glands and elevated levels of juvenile hormone. As a result, infected bees often don’t produce brood food and initiate foraging activities prematurely. Younger
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