Diagnosing and Treating Nosema in Honey Bees

All living things deal with diseases, and honey bees and their keepers are no exception. Our favorite pollinators can fall prey to many different kinds of viruses, infections, and parasites that can weaken the honey bees themselves, disturb the hive’s productivity, and threaten the livelihood of an entire colony. As a beekeeper, it’s important to learn as much as you can about the threats that put your honey bees at risk. When you know how to recognize, diagnose, and treat nosema and other common honey bee diseases, you have a better chance of eliminating these dangers before they can completely ruin your hives. Nosema is one of the most common diseases that threaten honey bees in the United States, but there are ways to both treat and prevent the issue. Learn how to best protect your colonies from the disease with this guide on diagnosing and treating nosema in honey bees.

Diagnosing and Treating Nosema in Honey Bees Mann Lake

What Is Nosema in Honey Bees?

Before you can prevent, diagnose, or treat nosema, you have 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 ceranrae. These parasites produce spores that contaminate a honey bee colony’s food or water supply. Worker honey bees unknowingly ingest the spores when they eat or drink. They might also accidentally pick up the spores when cleaning contaminated honeycomb or interacting with another honey bee or colony that has been infected. Once ingested, the spores begin to germinate within the honey bee’s mid-gut. As the fungus grows and multiplies, it absorbs nutrients and damages the cells, leaving the honey bee weaker and more vulnerable to other infections or diseases. A single nosema spore can grow into several million spores within a single worker. Some of these spores will then pass through the honey bee’s digestive system, producing spore-infected waste materials that can further contaminate the hive.

Common Signs and Symptoms of Nosema

Noticing nosema can be tricky as many colonies are nearly asymptomatic. As with many honey bee diseases, it’s important to pay attention to the productivity and population of your hive. 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 affects a honey bee’s digestive system, you can keep an eye out for symptoms related to digestive issues. Hives suffering from infections of the nosema apis parasite may display signs of dysentery, usually in the form of defecating on combs or on the outside of the hive. The honey 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 a nosema apis infection. Unfortunately, nosema ceranrae has few specific symptoms to distinguish it.

How Nosema Affects a Colony

Like many honey bee diseases, nosema weakens a colony and leaves it vulnerable to secondary infections, robbery from other hives and predators, and the harshness of the elements. A honey bee suffering from nosema will 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. 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, there are fewer adult honey bees around 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. Overall, the colony’s population drops, meaning less workers to maintain the hive and produce honey. This makes it hard to endure the winter. 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 accurately diagnose nosema. 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 hives of your fellow beekeepers.

Preventing Nosema 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 honey bees a better chance of fighting off the infection and its effects. You can do this by removing as many other stressors as possible and making sure your colony has access to a reliable food and water source throughout their foraging season. As mentioned above, sending in a sample of your honey bees for a nosema diagnosis can also help you prevent an outbreak of the 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 completely eradicate the disease.

All beekeepers want what’s best for their honey bees. 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 at Mann Lake today.

If you’ve dealt with nosema in your hives or are currently treating nosema in honey bees, we want to hear about it. Share your experiences and advice with us in the comments below.

Diagnosing and Treating Nosema in Honey Bees

2 thoughts on “Diagnosing and Treating Nosema in Honey Bees

  1. Dava Serbantes

    You covered almost all the topics. The one I don’t see is, “treatment” if you suspect Nosema?

    1. Krista


      For nosema treatment, we recommend Fumidil-B. It can be found here: https://www.mannlakeltd.com/shop-all-categories/hive-colony-maintenance/medications-treatments-herbicides/nosema

      Thank you and best of luck in all your beekeeping adventures!