Queens and Nosema ceranae

While I have only done it a few times, every once in a while a beekeeper will contact our lab and ask us to check a queen for Nosema spores. A couple weeks ago a beekeeper experienced unusual losses in his apiary. Since he wanted to cover all bases so to say, he also sent me a queen and a couple of workers from a dead out to examine for spores. Despite being sad about his losses, I was excited to do something out of the ordinary. For the most part, beekeepers and scientists alike are more interested in Nosema loads of worker bees. Nosema is one disease where I feel like queens are mostly forgotten about.

Because we now know that Nosema ceranae is more prevalent in the United States as opposed to Nosema apis, we can assume that any spores I find in the lab are of the N. ceranae species. I should also note that it is nearly impossible to distinguish the two species under the microscope because they are very similar in size. The only accurate method is to do a PCR assay of live bees.

Performing a spore count on only one bee is much simpler than doing so on 100. I placed the queen in a micro centrifuge tube, added 0.5 ml of deionized H20 and proceeded to grind her with a disposable tissue grinder. After grinding, I then added another 0.5 ml of deionized H20 (to make 1 ml total per bee). After a quick vortex to homogenize the spores in the sample, I pipetted a small amount of the solution onto a hemocytometer and looked at it under the microscope.

Fortunately for the beekeeper, this particular queen tested negative for Nosema. However, this brings up an important question. Most beekeepers know how Nosema impacts their entire hive, but how does it affect a queen? Farrar (1947) observed that Nosema-infected queens are more likely to be superseded. To further research this topic, Alaux et al. (2011) infected newly emerged queens with Nosema ceranae to study the effects on queen physiology. They found that infected queens had increased mandibular pheromone production, which may explain why infected queens have a higher rate of supersedure. To learn more about their research please check out their article published in Journal of Invertebrate Pathology here: (http://www.sciencedirect.com/science/article/pii/S0022201110002685)

Farrar, 1947 C.L. Farrar
Nosema losses in package bees as related to queen supersedure and honey yields
J. Econ. Entomol., 40 (1947), pp. 333-338

Alaux et al., 2011 Cédric Alaux, Morgane Folschweiller, Cynthia McDonnell, Dominique Beslay, Marianne Cousin, Claudia Dussaubat, Jean-Luc Brunet, Yves Le Conte
Pathological effects of the microsporidium Nosema ceranae on honey bee queen physiology (Apis mellifera)
J. Invert. Pathol. 106 (2011), pp. 380-385



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