Nosema Disease In Bees: What You Need to Know Today

bee near hive

Bee health is obviously an extremely important issue for beekeepers. To that end, those who are new to the hobby will need to be aware of the different diseases and pests that can affect the honeybee. Some of these issues are more serious than others, with some affecting honey production and others causing the destruction of the entire colony.

If you are a new beekeeper, take some time to read my series of articles on the various diseases and pests that could affect your hive. In this particular piece, I will focus on Nosema disease.

What is Nosema Disease?

Nosema disease – or nosemosis as it is also known – is a microsporidian classified as a fungus that affects the honey bee. There are two types of nosema microsporidian: Nosema apis and Nosema ceranae; both are tiny spores that attack the honey bee’s gut.

Indeed, Nosema disease is the most widespread disease affecting the honey bee; it is also one of the biggest threats to bees throughout the world.

How Does Nosema Disease Affect the Honey Bee?

As mentioned above, the tiny spores can affect the gut of the honey bee. Nosema apis originated in the European honey bee while Nosema ceranae is thought to have originated in the Asian honey bee. By far though, Nosema ceranae is the more serious threat to the bee as it attacks more of the cells in the gut. Therefore, it can kill bees much faster than Nosema apis does.   

Nosema spores enter the honeybee’s body through the mouth. To give you an idea of spore size, around 300 of them could fit on a pinhead. Just one spore is enough to cause infection in a bee, but a bee will typically ingest between twenty and ninety of these spores.

Once the spores have entered the bee, they germinate rapidly in the gut. Upon germination, they become active in the epithelial cells of the midgut. This is where it quickly multiplies, forming new spores. These spores will then pass to other tissues in the bee or will be excreted into the hive. If these spores contaminate food within the hive, other bees will become affected and the cycle continues. Unfortunately, the spores can remain viable for a number of months in spots of dried excreta within the hive.

Over the winter, it is likely that combs will become soiled with excreta from the infected bees. When other bees within the hive attempt to clean the combs in preparation for expansion in the spring, they too will become infected.

Bees affected by nosema disease are unable to absorb the nutrients they need. This often leads to them ingesting more food and using the protein to repair their internal body cells instead of using it to feed the larvae.

Infected nurse bees will be unable to produce royal jelly, which is usually fed to the brood. In an infected colony, a large number of eggs laid by the queen will not produce mature larvae. Infected queens often stop laying eggs and will die within weeks.

What are the Symptoms of Nosema Disease?

Alarmingly, bees affected with nosema disease often show no symptoms, making it difficult for beekeepers to spot the problem early. Alert beekeepers may notice that their bees are finding it difficult to fly and that there is excreta on the combs or dead/dying bees on the ground around the hive. However, these can also be symptoms of other diseases or pests, meaning that a correct diagnosis of the problem can be delayed.

So, as you have probably figured out by now, nosema disease can cause many symptoms and problems for honey bees, but none of these symptoms are specific to nosema disease. The only accurate way to detect nosema disease is with a lab examination.

Urban Beekeeping - Managing Hives in City Environments
  • Carter, Anthony (Author)
  • English (Publication Language)
  • 194 Pages - 02/28/2024 (Publication Date) - Independently published (Publisher)

If you do spot bees crawling around the front of your hive, check inside for other symptoms, such as dysentery (brown diarrhea in the case of bees). You will likely find this on the combs or even outside the hive. Be aware however that nosema disease does not actually cause dysentery, although infected honeybees are more susceptible to other infections that in turn can result in dysentery.

What to Do If You Suspect Nosema Disease

If you are worried that your colony might be infected with nosema disease, it is vital that you act fast. As mentioned above, the only way to be sure is with laboratory examination. The gut of a sample of bees must be examined under a 400x microscope.

What you can do beforehand is take a look at the gut of one of your dead bees. To do this, expose the gut by holding firmly on the stinger and pulling off the head. A healthy midgut will have a tan color and a ringed appearance that is similar to the body of an earthworm. If the gut is affected with nosema disease it will be less segmented, an off-white color, and may be swollen. If you notice any of these signs, it is time for a closer look under a microscope.

How to Treat Nosema Disease

As with everything else bee related, in the case of Nosema disease prevention (or management) is better than cure. To help prevent, or at least curb, the spread of nosema disease, it is best to be vigilant and take specific measures. Beekeepers should also send samples away for inspection every spring to ensure potential disease is spotted as early as possible.

This is a precautionary measure but if you do this, you will be able to implement other measures as early as possible.

You should also change combs regularly and make sure that you do not transfer combs from one hive to another. Promoting queens with high resistance levels is also wise, as is using feed supplements that can help with keeping disease levels low and creating stronger colonies. A strong colony is considered the best way to keep nosema levels at bay.

It is also important to reduce stress on your bees. One way to do this is by limiting or avoiding hive inspections and movements during the winter.

Some beekeepers prefer to use chemical treatment for nosema disease. Fumagillin is one such treatment that has been used, but research suggests that this chemical is not as affective at treating infections caused by Nosema ceranae.

Nosema Disease – Summary

In conclusion, nosema disease is a common and serious threat to honey bee populations around the world that can weaken or kill entire colonies if left untreated. Nosema is caused by a fungus that infects the gut lining of bees and can cause a range of symptoms, including reduced lifespan, decreased foraging ability, and weakened immune function. While there is no cure for nosema disease, there are several effective treatments and management practices that can help beekeepers to minimize the impact of this disease on their hives. These include using approved antimicrobial treatments, maintaining clean and hygienic hives, providing proper nutrition and hydration, and reducing stress factors such as overcrowding and environmental toxins. Additionally, it is important for beekeepers to monitor their hives regularly for signs of nosema and take steps to prevent the spread of the disease to other colonies. By following best practices for nosema management, beekeepers can help to promote the health and resilience of their bees and contribute to the sustainability of the beekeeping industry worldwide. Overall, nosema disease is a serious threat to honeybees that requires vigilance, knowledge, and proactive management to mitigate its impact and ensure the survival of bee colonies for generations to come.

Beekeeping Disclaimer:

Beekeeping, like any agricultural activity, involves inherent risks. It is important to understand these risks and take appropriate measures to mitigate them.

Potential risks associated with beekeeping include:

  1. Bee stings: Honey bees are generally not aggressive but can become defensive if they feel threatened or their hive is disturbed. Bee stings can cause allergic reactions or even anaphylaxis in some individuals, which can be life-threatening. It is important to wear protective clothing and follow best practices when handling bees to minimize the risk of stings.
  2. Diseases and pests: Bees can be vulnerable to various diseases and pests, including mites, viruses, and bacterial infections. These can have significant impacts on bee colonies, leading to reduced honey production or even colony collapse. It is important to monitor hives regularly and take appropriate measures to prevent and treat diseases and pests.
  3. Weather conditions: Extreme weather conditions, such as drought or cold temperatures, can affect the health and productivity of bee colonies. It is important to ensure that hives are appropriately sheltered and provided with adequate food and water.
  4. Environmental hazards: Bees can be affected by environmental hazards such as pesticide exposure, pollution, and habitat loss. It is important to be aware of these hazards and take appropriate measures to protect bee colonies and promote healthy environments for bees.
  5. Legal requirements: Beekeeping may be subject to local, state, or national regulations, such as registration or inspection requirements. It is important to be aware of these requirements and comply with them.

While beekeeping can be a rewarding and enjoyable activity, it is important to be aware of the potential risks and take appropriate measures to mitigate them. By following best practices and staying informed about the latest developments in beekeeping, beekeepers can help ensure the health and productivity of their hives and contribute to the well-being of bee populations worldwide.

Last update on 2024-04-17 / Affiliate links / Images from Amazon Product Advertising API

My new beekeeping log book is now available! "Beekeeping Log Book: 100 Log Sheets for a Complete Record of Your Apiary"

X
Scroll to Top