Nosema Flashcards
What is Nosema?
It is a microsporidium (a type of fungus). It is unicellular obligate intracellular spore forming parasite. The two types are :
Nosema apis
Nosema ceranae
Describe the lifecycle of Nosema
1) Adults ingest the spores
2) Spores germinates in the mid-gut (ventriculus)
3) Long coiled filaments penetrate the peritrophic membrane and infect the cells.
4) The organisim replicates in the wall lining and produces spores
5) These cells rupture and cause the spores to enter the faeces which then contaminate the comb
How long do nosema spores last for?
1 year in faeces
4 years inside larval remains or dead bees
4 months in honey
When infected, how many nosema spores may be in the bees gut?
30-50 million
Why are there often 2 spikes of Nosmea in a year?
The first is in the spring when brood rearing starts as cells need to be cleaned out. The second is when the honey crop begins for the same reason.
What are some generalist impacts for Nosema?
- Protein digestion is inhibited due to the enzyme producing cells being damaged
- Reduces the lifespan of bees, and can cause nurse bees to underperform
- Queen may slow down egg laying as she is fed less
- Can prevent hypopharyngeal glands to fail to develop properly so the bees become guards / foragers quicker
- Modified pheromone production
Why does Nosema ceranae cause viruses to harm the bee?
N.apis only damages epithelial cells whilst N.ceranae damages epithelial and basal cells so viruses and bacteria can enter into the bee
How fast are the two types of Nosema?
N.apis = fast acting, short duration
N.cerane = much slower dwindling over time
Which type of Nosema caused foragers to be more risky foragers by going out at colder temperatures?
Nosema Cerane
What is dysentery?
Digestive distress. It is caused by poor diet such as honey with too high moisture content or fermented stores. This can help spread nosmea
How should Nosema be treated?
A Bailey comb change is recommend as it does not crush the bees like a shook swarm and this would cause spores to be released.
How do you carry out a field diagnosis of Nosema?
1) Find a crawling bee and hold it in your fingers
2) Draw out the gastrointestinal tracts by grasping the last abdominal segment and pulling
3) The midgut (the nearest section to the thorax) should be tan coloured and wrinkly. If white and smooth it is likely Nosema is present.
Outline a basic diagnosis for nosema (the way a beekeeper could do it)
1) Collect 30 foraging bees from the entrance
2) Kill by freezing
3) Remove abdomens and crush in 3ml of water with a pestle and mortar.
4) Place a single drop of suspension on the slide and view under 400x zoom
5) Nosema spores look like oval rice shaped grain spores
Describe a laboratory diagnosis for Nosema
1)10 bee abdomens are finely ground in 5ml of water
2) Filter the suspension through a muslin to remove debris
3) Centrifuge for 6 minutes at 800g force
4) Remove the supernatent (excess liquid)
5) Fill a haemocytometer and count the spores and then use a PCR to test the species
How big is a nosema spore
4 by 4 um
