What are the signs of a honey bee colony having nosema?

Today, we are going to look at how we can recognize, diagnose, and treat for Nosema.  If beekeepers can diagnose nosema early, the better chance the colony will survive.  Nosema is the most common disease for honey bees here in the United States, but there are ways to both treat and prevent the disease.

 

WHAT IS NOSEMA

We must first understand what nosema is and how it spreads.  Nosema is a fungal disease that comes from one of two fungal parasites: nosema apis or nosema ceranrae.  Each of these parasites produces spores that will contaminate the water and food sources within the hive.   The worker bees unknowingly eat the spores when they eat or drink.  Worker bees can also spread spores when they are cleaning contaminated comb and frames.   Once spores are ingested, the spores begin to germinate within the honey bee’s mid-gut.  A single spore can grow and multiply into 2 million spores in a single honey bee.  Nosema also absorbs nutrients and damages the cells within the honey bee, leaving the honey bee weaker and more vulnerable to other diseases.  As nosema spreads within the colony, the honey bees are producing spore-infected waste material which will contaminate the hive.  We can think of this as our honey bees having diarrhea or dysentery.

 

COMMON SYMPTOMS OF NOSEMA

Nosema directly affects a honey bee’s digestive system.  Colony’s suffering from the nosema apis parasite may display signs of dysentery.  This can be seen in runny yellow or golden drop marks that can measure ¼” to 2” in length.   usually in the form of defecating on combs or on the outside of the hive.   Nosema dysentery stains are normally found on the outside of the hive and above the entry way of the hive.  Honey bees may 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.  But again seeing yellow or golden drop marks are a sure sign nosema is evident within the colony.

 

HOW NOSEMA AFFECTS A COLONY

Nosema weakens a colony and leaves it vulnerable to robbery from other hives and predators. Honey bees suffering from nosema will have a weakened immune system and digestive tract. The infected bee may have digestive issues for the rest of its life, which is why dysentery is a common side effect of nosema apis.  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.

If a queen bee becomes infected with nosema, she cannot lay as many eggs and will often have a shorter lifespan.  The end of the colony is now numbered, the colony’s population drops, meaning less workers to maintain the hive.  A continued lower colony population now makes it hard to stay warm during the winter months.  The end result is the colony will freeze out during the winter months.

 

PREVENTING NOSEMA IN YOUR HIVE

Once a week walk through your bee yard and look for nosema.  You do not have to inspect the inside as the first signs of nosema will be dysentery drops on the outside of the hive.  Keeping a healthy, well-populated, and productive colony gives your honey bees a better chance of fighting off the infection.

Making sure your colony has access to a reliable food and water source (1:1 sugar water ratio) throughout dearth periods.   This can be done with internal feeders such as a top feeder or a frame feeder.  Keeping your bees hydrated is so important as it will help your colony work through the nosema dysentery.  I do see nosema on some occasions and utilizing a 1:1 sugar water ratio will, 95% of the time, cure the nosema within the honey bee within one week if caught early.

It is also important to wash the outside of the hive where the dysentery stains are as that is spores that could re-contaminate the hive.  This can be done with Dawn dish detergent and luke warm water.  I would recommend do it once a day until there are no more stains on the outside of the hive.

If the outside of the hive is covered with dysentery stains, you will want to inspect the inside of the hive.  You will need to pull all the frames from the hive and look for internal dysentery stains on the inside of the hive.  It here are stains, you will need to wash the inside of the hive.

If you see dysentery on the frames, you will need to replace each frame as it will have nosema spores present on those frames.  Place new frames and foundation in the hive where needed.  I suggest disposing of any contaminated frames as they are still carrying the nosema spores.

Preventing robbing is also an important item to ensure your colony’s health.  Robbing will spread spores to a new healthy hive.  Preforming a hive inspection on a weekly basis will keep you “in the know” before nosema crashes your hive.

All beekeepers want what’s best for their honey bees. When you provide the best you give your colonies the best chance at survival.