Can I NOT Have Nosema?

[malawi2854]

Hello all,

Before spending out on Fumidil-B for my 3 colonies, I thought I would have a go and looking to see if my bees actually HAVE nosema first...

I collected bees from the entrance yesterday, froze for 24 hours, thawed this evening and got busy chopping them in half, and mashing up the remains... not a very pleasant job.

Once I had the bee soup, I put it under the microscope (which I was able to borrow from the Biology lab of the school I work at.
After much fiddling and faffing about, I actually managed to see something... I've no idea WHAT... but definately SOMETHING!

I saw an awful lot of round blobs, and a few much bigger, long twisty bits, which I assume are bits of bee gut - but couldn't find any tic-tac's indicating Nosema.

How likely is it that I just DON'T have it?

I have 3 samples, and have only looked at one so far... but before I chop up any more bees, I would like to make sure I know what I'm looking at!

Don't suppose anyone has any Nosema-riddled bees they'd like to donate for comparison purposes?!?

 

[johnandyrob]

Yet again I would link but still dont know how to. put norsema in the search go to page 4 " looking for norsema " their are some slides on there

 

[malawi2854]

Thanks - I have just been looking at that very thread, actually...

The initial pictures are quite difficult to make anything out from - as for the later pictures, with the measurements, I could have some of them... I thought Nosema was very uniform in shape and size? Those images make them look rather more "random"!!!

I was using this as my reference...
[ame="http://www.youtube.com/watch?v=UQcjh02sCd0"]http://www.youtube.com/watch?v=UQcjh02sCd0[/ame]

 

[Poly Hive]

The honest answer is it is unlikely you do not have it or rather your bees do.

The classic description is "rice grains"

PH

 

[mbc]

I was told that the recent apiary survey by the bee inspecters showed about half the apiaries surveyed had nosema of one sort or another, this must mean half are clear of nosema.

 

[MuswellMetro]

A Nuc made from Nurse bees is less likely to have Nosema in identifiable quanities

i found all but one of the summer nuc we checked were free even though the parent colonies were riddled with nosema. on a scale of 1-10 one parent hive was a 15, nuc from it still only showed one nosema cell in the field of view at 400X

The Nuc are less likley to show it as the foragers who are infected have returned to the old hive

BUT the low level in the Nuc you do have will mean Nosema can re appear in the next year

 

[Arfermo]

In a recent talk at my BKA, the very experienced speaker advised that most hives have it to some degree such that bees can accomodate it without being so ill that they snuff it and that the most sensible thing to do is to ignore the possibility until one seen bee poo dripping down the outside of the entrance and elsewhere. In short don't look for trouble where it is least likely to exist - there are better things to do!!! As one wishes p'raps?

 

[greatbritishhoney]

In a recent talk at my BKA, the very experienced speaker advised that most hives have it to some degree such that bees can accomodate it without being so ill that they snuff it and that the most sensible thing to do is to ignore the possibility until one seen bee poo dripping down the outside of the entrance and elsewhere. In short don't look for trouble where it is least likely to exist - there are better things to do!!! As one wishes p'raps?

I heard just the opposite from our bee inspector.
He said that, yes, many hives have it and display no obvious outward signs, but then die off over winter.
A strong colony may be able to overwinter with nosema but I would worry that a weaker colony may struggle, especially if it's a harsh winter.

 

[Meg]

Yes, the random apiary sampling carried out by the inspectors does show that a high percentage of colonies show one or both types of nosema. However, if there is only a low level, then it is not a problem.

I would suggest that testing is essential to find out just what level of infection you have. Just because a colony shows symptoms of dysentery does not mean it has nosema and vice versa.

Personally I would rather test and then treat if necessary now rather than have them dying out over the winter.

Meg

 

[MandF]

That video was made by one of my association colleagues.

Anyhow, one giveaway with nosema is they move.. if you look closely they wiggle. Nothing else that size/shape does.

If you see 1 or 2 per screen it is ok I believe. if you see more then its best to treat.

 

[huntsman666]

Why not do a visual field test first?

You need about 30 live bees per colony.

Remove head and grasp the last segment and sting with a tweezers and gently holding the thorax, slowly but firmly pull the sting and last section away.

The rectum and midgut will follow.

Once the midgut has emerged, put it on a piece of white paper.

If the midgut is a tan colour and wrinkly, it is healthy.

If white and smooth, it possibly has Nosema.

 

[alanf]

The initial pictures are quite difficult to make anything out from - as for the later pictures, with the measurements, I could have some of them... I thought Nosema was very uniform in shape and size? Those images make them look rather more "random"!!!

Not claiming massive expertise in Nosema detection myself but we had an afternoon examining samples from various hives with an experienced tutor which included some heavy infections. There is no real substitute for being shown how to do it. Having some microscope experience from way back also helps but listing a few points we went over might help.

Collect the sample.

You need adult bees, returning foragers are ideal. Nosema is spread adult to adult through spores in the waste. The part of the life cycle you are looking for is the spores in the gut, spores only appear in numbers 7-10 days after infection. Returning foragers also have pollen which provides a handy scale under the microscope (larger than the spores). Overnight in the freezer is the usual way of preserving the sample.

Preparation:

Separate the abdomen from the rest of the body from about 30 bees. Sharp pointed scissors are probably easiest to use. 30 gives an average sample since not all bees will have the same level of infection. Abdomen only; legs and wings just get in the way. Put the abdomens and only enough water to make the sample mix in a pestle and mortar. You are trying to empty the guts by squeezing and rolling the abdomen, mash too hard and you get more debris which makes the spores harder to see. One drop of the cloudy liquid on a slide, add a cover slip. This preparation doesn't allow a quantitative measure but do it consistently and you can grade infection rates in samples as high, medium, low or absent.

Viewing

Start at 100x to coarse focus then turn to 400x. If your sample has pollen you should see spores which appear as smaller 'rice grains' among larger pollen grains. They are uniform in size, other sizes may be debris or air bubbles. Once you have a high to moderate infection to view and 'your eye is in' they are quite easy to spot. You might need fine focus to scan up and down through the depth of the liquid. Check over the whole slide, spores might not be distributed perfectly. There are subtle differences between Nosema apis and Nosema ceranae in spore shape but difficult to see under a light microscope. If the treatment is the same (Fumidil B) there is little practical point in going beyond the infection level.

Remember to wash equipment thoroughly every sample or they will all have Nosema spores.

In autumn you're seeing the bees that will be around next spring. The effect of Nosema is to weaken the adults and shorten their life. Reducing infection rates before all the adults are infected means more adults over winter and are ready to raise brood in the spring.

 

[MandF]

One point - whilst strictly speaking you should only grind the abdomens, you can just grind the whole bees. You get more "stuff" under the microscope, but that can make inspecting slides more interesting.

As for checking the whole slide - you obviously only need to take a sample of the slide contents, ie check 4 or 5 different areas, not religiously inspect every part of the slide.

 

[huntsman666]

Why not only remove and use the ventriculus (midgut)?

 

[alanf]

One point - whilst strictly speaking you should only grind the abdomens, you can just grind the whole bees. You get more "stuff" under the microscope, but that can make inspecting slides more interesting.

As for checking the whole slide - you obviously only need to take a sample of the slide contents, ie check 4 or 5 different areas, not religiously inspect every part of the slide.

Why not only remove and use the ventriculus (midgut)?

Just describing what worked for us. I have read instructions that include putting whole bees in liquidisers; quicker prep, longer under the lens and washing up. Drawing out the gut is possible but harder to teach although a useful skill once you can do it. As described to us, snipping the abdomen is easy to reproduce without a lot of practice and leaves a fairly clean slide. It's a compromise. Dependant on how many samples you have, how much time and the skill level of those doing it.

Yes, don't count every mm of slide, just view enough to check that you don't have a clump of spores in one corner.