Nosema

What you may have learned about nosema in your beekeeping courses and books is no longer true. Diarrhea is no longer a symptom of nosema. The 'new' nosema is a largely invisible bee disease that silently kills off foragers and impacts the nutrition of nurse bees (and by extension, the larvae they feed), weakening the hive. When you search for signs of disease but you aren't sure what is wrong inside your hive, there's a decent chance that it's nosema.

Pathogen Type:

Fungus

Symptoms:

* Diarrhea is NOT a symptom of the new strain of nosema

~ Dwindling forager population (less activity at hive entrance)

~ Eventually, dwindling worker population (not enough bees to cover brood)

~ Generally small, weak hive

~ Not building up population in spring

~ Not producing honey during a flow

Diagnosis:

~ Microscopic analysis is required to diagnose nosema (send away 50 dead bees for testing)

Season/Location:

~ Nosema is usually most apparent in spring when a hive fails to build up as expected or during a nectar flow when the hive fails to store any honey

~ All locations

Prevention:

~ Good hygiene practices between hives/yards

~ Cycle out old brood comb

~ Do not overstress colonies

~ There is some evidence that probiotic supplements (like Hive Alive or Bee ProHealth) can help prevent nosema

Treatment:

~ Reduce hive space (so the bees fill the space)

~ Boost the hive with a frame of brood from another hive

~ Feed 1:1 sugar syrup AND pollen patties

~ Add Hive Alive to sugar syrup

~ Fumagellin (an antibiotic) is often prescribed for nosema and has been used prophylactically in the past. There is evidence that it is not as effective against the new strain of nosema. Prophylactic use of antibiotics is also problematic.

What Does The Research Say?:

This article offers a review of several avenues that researchers are pursuing currently to treat nosema, including some natural extracts and supplements, and microbial supplements (good bacteria).

This study exposed honeybees to different combinations of pesticides and levels of nosema at the same time and found that they two exacerbated one another significantly. This means that a colony might survive exposure to one, but collapse if exposed to both.

Looking for more?

Looking for more beekeeping education? You can find my virtual, on-demand course Intermediate Beekeeping for Year 2 and Beyond at https://courses.rushingriverapiaries.com/courses/intermediate-beekeeping

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