# More ... > Beekeeper education >  Honey crop (Module 2)

## Mellifera Crofter

I'm reading an article in the July issue of BeeCraft by Eleanor Witter (What we should expect to find in honey, Part 2), saying (in brackets, as an aside to the article):




> (A fascinating feature of the proventriculus is that its four lips sieve out pollen, and even some bacteria and spores, allowing filtered nectar to pass through into the ventriculus.  That means that the nectar passed from bee to bee during the honey conversion sequence in the hive is already partly filtered.)


I understand the first sentence.  The second sentence bothers me as I thought that the nectar that's being passed from bee to bee stays in the honey crop and does not reach the ventriculus.  I therefore cannot see how the nectar can be partially filtered as the proventriculus is at the far end of the honey crop - or am I wrong?

Kitta

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## gavin

Don't necessarily believe all you read in Bee Craft (Oh, that's what you're doing) or even knowledgeable bee fora!

As I see it, the first sentence is half-wrong and the second sentence, the one you are questioning, is right!  

The proventricular valve partially filters the crop contents and passes the material filtered out (along with some nectar) into the gut.  The partially filtered nectar isn't then passed down into the deeper parts of the bee, it is regurgitated for drying or passing on. 

MArk Winston, The Biology of the Honey Bee, p. 115:

In addition, workers ..... may remove spores from infected honey taken into the crop by the action of the proventriculus straining out the spores (Thompson and Rothenbuhler 1957).

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## gavin

The proventricular valve has a pump action and a fringe of hairs that filter out the particles in the crop before passing down a bolus.  Everything you wanted to know about the proventriculus was reviewed by Leslie Bailey and is freely viewable in the PDF here:

http://jeb.biologists.org/content/29/2/310.abstract

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## Mellifera Crofter

Yes - I suppose I should rather buy the Winston book than seeking knowledge in BeeCraft.

My head is spinning in confusion now, Gavin - but I can also see that I did not frame my question properly.  (I so often get my sentences wrong!)

Nectar going from the crop to the ventriculus is filtered - I understand that.  But that nectar isn't then passed back up through the ventriculus into another bee's mouth in a nicely filtered state (as EW is saying in her second sentence) - or is it?  Once through the proventriculus it can only go out and out and onto the washing.

I'm now also curious what is partially wrong and partially right in the first sentence.

Kitta (and I hope I did not mangle my thoughts again.)

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## gavin

> Nectar going from the crop to the ventriculus is filtered - I understand that.


No, nectar doesn't normally go from the crop to the ventriculus, at least not in quantity.  The proventriculus sticks out into the crop or honey stomach.  It manages to filter particles, gather them up, and pass them in a lump down into the ventriculus without there being a significant flow of nectar in that direction.  The nectar remaining in the crop gets depleted of particles.





> I'm now also curious what is partially wrong and partially right in the first sentence.


Which was:
(A fascinating feature of the proventriculus is that its four lips sieve  out pollen, and even some bacteria and spores, allowing filtered nectar  to pass through into the ventriculus.)

*Some* might make that jouney but most doesn't.  The filtered nectar stays in the crop until the bee is ready to regurgitate, the solid matter heads down the digester.  So the first sentence is right about the 4 lips filtering out particles, but wrong that a passage of nectar to the ventriculus is involved.

Do have a go at the Bailey paper mentioned above.  Access to the full PDF is free.

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## Mellifera Crofter

> ...The nectar remaining in the crop gets depleted of particles.  ...


Thank you Gavin - at last, the penny's dropped!  That explains nicely why the next bee gets partially filtered nectar.  Thanks.

I did read the paper, Gavin, and understood about the forming of boluses and so on - but I did make this mistake in thinking the nectar must pass through the proventriculus to get filtered.  I also mistakenly thought it only starts working (allowing nectar to pass through to the ventriculus) when the bee is hungry and needs to digest some food.

Thanks,
Kitta

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## gavin

Here's a more popular article:

http://livingwithinsects.wordpress.c...ticle-remover/

Imagine the crop is a small rock pool.  There's the stump of a piece of seaweed sticking out which has four large barnacles on the end.  The barnacles will filter out particles in the small rock pool.  Easy!  :Big Grin: 




You'd also have to imagine that the rear ends of the barnacles were connected to an insect gut system to make this work, but that's the principle.

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## gavin

Ah! Too late.  Maybe that will help someone else thinking about this.

G.

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## Mellifera Crofter

Excellent!  Thanks for the barnacle video!  Kitta

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## gavin

That's the second time I've posted a video with barnacles on SBAi.  Anyone remember the first?

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## Mellifera Crofter

... and thanks for the easy-to-read article, Gavin.  It's good.

PS:  No - I haven't seen the video before ...

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## gavin

Perhaps some old threads are best left to die .... but here it is.  Different video and indeed mostly a different filter feeder but barnacles do feature near the end.

http://www.sbai.org.uk/sbai_forum/sh...r-puzzle/page8

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## Mellifera Crofter

The thread was far above my head first time round, Gavin, and still is - so I'm leaving it well alone.  But the clip provided a happy diversion from work.  Thanks!

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