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Dave G

Some new research on Varroa

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Turns out we've had the wrong assumption about how Varroa mites feed off bees.....

 

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APRIL 10, 2017

Doctoral candidate Samuel Ramsey won the University of Maryland’s Three Minute Thesis (3MT) competition. Ramsey, a student in the Department of Entomology, was selected by a panel of judges from nine UMD finalists during a live competition held April 5 2017

https://www.gradschool.umd.edu/newsroom/3563

 

 

He also has a few You tube videos as "Dr Buggs"...the one I watched was stressing the importance of varroa in the Colony collapse issue rather than all the media focus on pesticides.

Sure sounds like hes on the bees side.

 

 

 

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Taking it as true for now, it is certainly interesting! I wonder where this will go! 

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it wouldn't surprise me if it was correct (but i doubt it will be that groundbreaking).

it often puzzles me how little we know and how much we just accept as fact.

 

i remember once sitting in a truck with a scientist on varroa and asking her a question that i had for a long time:

if a mite spends 14 days in a capped drone cell and than 3/4  offspring hatch, those after only a few days reenter into drone cells and hatch 14 days later with 3/4 mites offspring of their own, then in theory a much higher reproduction rate must be possible than what we are told.

misses Dr Dr arrogantly replied that everyone knows that mites double or triple per month and i haven't got a clue what i was talking about.

so yes, totally possible nobody ever checked what they feed on and also possible our mites reproduce 5 times faster than we think when the infection rate is only low, cos i don't think anyone has ever bothered to check.

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it's actually sad that university and science is mainly about how you present yourself and your stuff and how good you are in securing founding rather than actually "doing good research"

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Like so much else I guess, what circles you travel in and who you know politically rather than what may be for the greater good.

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It has been known for some time now that varroa feed on the fat not the blood. I think what Samuel has done is find a new way to demonstrate that.

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10 hours ago, Trevor Gillbanks said:

Interesting.  Where is @Dave Black when you need him.

 

True or false please Dave

As you've mentioned it I'll have a look when I get to a computer. I don't watch unsolicited videos with no synopsis, especially on the phone! 

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10 hours ago, Alastair said:

It has been known for some time now that varroa feed on the fat not the blood.

Well now I know too

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Interesting video. He starts off by mentioning coffee depending on bees for pollination which may be right but all  coffees New Zealand relatives are wind pollinated. How long before someone can come up with an artificial bee fat that's attractive to varoa and can have something unfriendly added to it.

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Maybe that's a potential byproduct of alcohol varroa testing. Fat is soluble in alcohol. Squash the bees up a bit, maybe a blender, filter the solid bits out, evaporate the alcohol, and maybe what's left is bee fat ?  Dash of fipronil......oops I mean amitraz or something...

 

Edited by yesbut

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On 10/13/2017 at 8:19 PM, Trevor Gillbanks said:

Interesting.  Where is @Dave Black when you need him.

 

True or false please Dave

It isn't the case that everyone simply assumed haemolymph was the food source; there have been a few studies that suggest that is the case. In 2004 for example Garedew looked at the energy and nutritional demand and studied mite respiration and calorimetry, measuring oxygen uptake and heat production, and the loss of weight for the various castes and their larvae. DeJong, Bailey and Ball, Kovac and Crailsheim and others studied the chemical composition of the haemolymph and found lower protein content in parasitized pupae (circa 1982 - 1991). Mites have been found to have few enzymes for digesting proteins, supporting the idea that they get their amino acids from bee haemolymph instead.

 

It is the case that we really know very little about mite nutrition though. Mites use different food sources at different times, foundress mites live in brood food, phoretic mites probably have different needs winter to summer, and mites feed on larvae that have very little in the way of distinct organs. What we all refer to as 'the fat body' is not a 'thing'. In larvae the 'fat body' is a very loose association of specialised cells, so loose that as the development stages progress through to pupation they can be free-floating in the haemolymph or completely reabsorbed. In adults most of the 'fat body', which by now is more like a proper 'organ', is found along the dorsal (top) ceiling of the abdomenal cavity, with some on the abdomen floor, and sometimes extending a little up the sides close to the wax glands. That only roughly coincides with the diagram in the video. I'd expect that any trend in the protein and lipid status of the haemolymph would be mirrored in the fat body and vice versa.

 

Bowen-Walker did find a distinct preference for feeding site in adult over-wintering bees, limited by the number of mites trying to feed. The preference was clearly for a posi between the 3rd and 4th tergites, avoiding the wax mirrors, on the left-hand side of the abdomen. 85% of the 77% of the mites on the abdomen were there, 66% of them preferred the left side. 99% were found between tergites in preference to the sternites where the most significant 'fat body' would be. I don't think we have seen a similarly emphatic preference in larvae or pupae. In this case they suggested the choice of site was due to the proximity of the curve of the mid-gut (especially when the rectum was full) that would mean it would be the most concentrated region of haemolymph.

 

Given what we know I would have some questions about the idea expressed in the video (it may be simplified account...). I'm not convinced we can jump straight to filling the 'fat body' with anti-varroa meds. That said using a fluorescence trace is an interesting idea, an alternative would be using radioisotopes of carbon to work out what came from where, because we aren't sure. I'm guessing this is a PhD thesis in the making, Ramsey was working in Dennis vanEnglesdorp's lab, but so far the only reference to the work is in a presentation to a 2016 conference. Maybe one day it will get published and peer reviewed.

 

Garedew, Schmolz, and Lamprecht (2004) The energy and nutritional demand of the parasitic life of the mite Varroa destructor. Apidologie 35 pp419-430 doi: 10.1051/apido:2004032

 

Bowen-Walker, P. L., Martin, S. J., & Gunn, a. (1997). Preferential distribution of the parasitic mite, Varroa jacobsoni Oud. on overwintering honeybee (Apis mellifera L.) workers and changes in the level of parasitism. Parasitology, 114(2), 151–157. https://doi.org/10.1017/S0031182096008323

Edited by Dave Black
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On 10/13/2017 at 8:19 PM, Trevor Gillbanks said:

Interesting.  Where is @Dave Black when you need him.

 

True or false please Dave

A little more on this guy Samuel Ramsey - University of Maryland https://www.researchgate.net/publication/305805061_Identifying_the_primary_host_tissue_composing_the_diet_of_a_honey_bee_parasitic_mite_Varroa_destructor

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Some clever Kiwi is going to work this issue out I feel.

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