Diagnosing and Treating Nosema in Honey Bees thumbnail image

Diagnosing and Treating Nosema in Honey Bees

As a beekeeper, it’s important to learn as much as you can about the threats that put your bees at risk. Infected honey bees can be extremely damaging to the hive, no matter the season or climate.

In this post, we’ll discuss the risks and dangers associated with Nosema, a common fungal disease that impacts bee colonies and hives around the world.

Diagnosing and Treating Nosema in Honey Bees

All living things deal with diseases; honey bees and their keepers are no exception. Our favorite pollinators can fall prey to many viruses, infections, and parasites that can weaken the bees themselves, disturb the hive’s productivity, and threaten the livelihood of an entire colony.

Nosema is one of the most common diseases that threaten honey bees in the United States, but fortunately, there are ways to both treat and prevent the issue from permeating honey bee colonies and resulting in sick bees.

When you know how to recognize, diagnose, and treat a nosema infection and other common bee diseases, you have a better chance of eliminating these dangers before they can completely ruin your hives.

Learn how to best protect your colonies from the disease with this guide on diagnosing and treating nosema in honey bees.

What Is a Nosema Infection In Honey Bees?

Before you can prevent, diagnose, or treat nosema, it’s crucial to understand exactly where the disease comes from and how it works.

Nosema is a fungal disease that comes from one of two fungal parasites: Nosema apis or Nosema ceranae. These parasites produce nosema spores that contaminate a honey bee colony’s food or water supply. These parasites and infections have drastically impacted the honey bee population in the last 50 years, so it’s no surprise that beekeepers are concerned about their hives becoming infected.

Worker honey bees unknowingly ingest the spores when they eat or drink. They might also accidentally pick up the nosema spores when cleaning contaminated honeycombs or interacting with another honey bee or colony that has been infected.

Once ingested, the Nosema apis spores begin to germinate within the honey bee’s mid-gut. As the fungus grows and multiplies, it absorbs nutrients and damages the cells, weakening the honey bee and making it more vulnerable to other infections or diseases.

A single spore can grow into several million nosema spores within a single worker. Some of these spores will then pass through the bee’s digestive system, producing spore-infected waste materials that can further contaminate the hive should any bees come into contact with it.

Nosema Ceranae vs. Nosema Apis

Nosema ceranae evolved with Asian honey bees and poses a serious risk for infected hives worldwide. The fungus apis can hurt a hive, but Nosema ceranae is much more harmful.

For European honey bees (also known as Western honey bees), Nosema ceranae can be difficult to identify because the symptoms are difficult to pick up on. The treatment for Nosema ceranae is also challenging because there’s no clear-cut answer yet, as the fungus is fairly new to the US and Europe.

Both Nosema ceranae and apis infect worker bees, the queen, and the drones in the hive. Symptoms of a nosema infection are typically more common in the cold and wet months. Nosema ceranae infections can result in population loss any time of year, but it’s heaviest during the winter.

Common Signs and Symptoms of Nosema

Noticing Nosema ceranae can be tricky as many colonies can present as almost entirely asymptomatic.

As with many bee diseases, it’s important to pay attention to the productivity and population of your hive. Poor honey bee health can be tricky to pick up on, but it begins with keeping an eye on your hive's general health and productivity, noticing patterns or behaviors that don’t appear normal.

A slow spring, reduced honey production, fewer worker bees, or a smaller brood are all signs that something is weakening the colony.

However, because Nosema apis can significantly affect a honey bee’s digestive system, you can keep an eye out for symptoms related to digestive issues. Hives suffering from infections of the apis parasite may display signs of dysentery, usually in the form of defecating on combs or on the outside of the hive.

The bees themselves might also display symptoms such as swollen greasy-looking abdomens, trembling, or holding their wings at odd angles. These are all potential symptoms of nosema apis infection.

Unfortunately, Nosema ceranae has very few specific symptoms to distinguish it, and sending bees to a laboratory for examination is the only effective way to receive a diagnosis of Nosema ceranae.

How Nosema Infections Affect a Colony

Like many honey bee diseases, nosema disease can weaken a colony and leave it vulnerable to secondary infections, robbery from other hives and predators, and the harshness of the elements.

Infected bees will often have a weakened immune system and digestive tract. The infected bee might have digestive issues for the rest of its life, which is why dysentery is a common side effect of Nosema apis infections.

Furthermore, when a young worker bee is infected, she becomes unable to produce brood food. This leads to her becoming a forager bee at an early age. As the infection spreads through the hive and causes more workers to become foragers, fewer adult honey bees remain to care for the brood.

Meanwhile, an infected queen bee cannot lay as many eggs and will often have a shorter lifespan due to the disease.

Over time, the colony’s population drops, meaning fewer workers are there to maintain the hive and produce honey. This makes it hard to endure the winter season and colder weather.

Even if the colony survives until spring, they won’t have the workers necessary for a quick honey build-up, which means the odds are already against them for the next season.

How to Diagnose Nosema in a Hive

Unfortunately, many of the symptoms of nosema are simply indicators that something is generally wrong with the hive. As such, there are no reliable field diagnoses for the disease. You need laboratory equipment and some training to diagnose nosema accurately.

If you believe your honey bees might be suffering from nosema, you can collect a sample of members of your colony and send them to a local lab for diagnosis.

Many beekeepers do this every spring regardless of known symptoms. Regular sampling and diagnosis can help you catch the disease early if it does occur and prevent an outbreak among your hives and the honey bee colonies of your fellow beekeepers.

Preventing Nosema Infections in Your Hive

Despite the difficulties of diagnosing and treating nosema in honey bees, there are several ways to prevent the spread of the disease in the first place.

As with many diseases, keeping a healthy, well-populated, and productive colony gives your bees a better chance of fighting the infection and its effects. You can do this by removing as many other stressors as possible and ensuring your colony can access reliable food and water sources throughout its foraging season.

As mentioned above, sending in a sample of your bees for a nosema diagnosis can also help you prevent an outbreak of infection.

Finally, avoid contamination from other infected hives. There are two ways to do this. The first is to prevent robberies between hives by protecting healthy hives or isolating infected hives.

The second way to prevent cross-contamination is by sterilizing your equipment. Thoroughly disinfect your hive tool, bee brush, protective gear, and any other equipment you use in your apiary. If an infected hive survives through nosema treatments, be sure to disinfect the hive itself to eradicate the disease completely.

Cleaning the Hive after a Nosema Breakout

Nosema infections can devastate a hive, and cleaning up after the fact is critical to ensure no reinfections occur.

Common cleaning methods for the hive are scorching or fumigation; however, fumigation can often present its own set of risks because of the hazardous chemicals necessary for safe and proper disinfecting. Many bees are sensitive to the toxins in the chemicals used for cleaning.

For this reason, many beekeepers choose to disinfect their wooden hives by scorching or using heat and fire to clean and kill off any remaining fungus.

You’ll likely have to take your beehive apart in order to scorch it properly. You can safely fumigate or scorch the hive body, bottom board, inner cover, and any other wood parts of the hive. Be sure to scorch the hive tools you used as well.

Scorching temperatures should reach at least 104 degrees Fahrenheit and be kept hot for at least four days to ensure all the Nosema spores are effectively killed.

Keep Your Hive Healthy and Strong with Mann Lake Supplies and Resources

All beekeepers want what’s best for their hives. When you provide the best hives, equipment, medications, and other honey bee supplies, you give your colonies the best chance at survival. Keep your apiary strong and successful by shopping for all your bee supplies and tools at Mann Lake. We strive to provide the best quality resources, equipment, and knowledge base to support any beekeeper throughout their journey.