Varroa

[mbc]

Third hand from the" thoughts on swarming thread" there's mention of varroa being canibalistic towards each other.

 

[Bcrazy]

Hi mbc,
Please expand and inform us of what you have seen please. Ta.
Mo

 

[Skyhook]

There was a thread with a link on here a while ago showing footage of mites in cells. The researcher casually mentioned, almost as a throwaway remark, that they had one hive in which the larvae masnaged to exclude the mites from the coccoon, entombing them between the coccoon and the cell wall. Does anyone know anything about this? It's the only mention I've come across.

 

[Skyhook]

Today i found a couple of Varroa mites grappling each other whilst waiting for me to photograph them. does any think that Varroa are aggressive toward each other and this might cause damage to one or the other and the beekeeper considers this (his bees are attacking Varroa).
I suppose it is possible to some degree where mites will fight given the right circumstances.

Thoughts anyone??????//

Mo

Certainly puts a lot of the current research into a different light, and a big dissapointment for Ron Hoskins if its true! He may just have been developing more belligerent mites.

 

[rowbow]

Sex act?, could the legs be pulled off when the bees pull then away from each other dent's in outer case could be the result of being pushed.

John

 

[mbc]

Hi mbc,
Please expand and inform us of what you have seen please. Ta.
Mo

Third hand : posted by Sommerford but attributed to Peter Kemble

"Varroa mites are to some extent cannibalistic which might explain the reduction in viable mites but, whatever the reason, we have found that these new colonies are nearly always the best ones the following year, with young queens and a minimum of mites."

The full quote is here:

http://www.beekeepingforum.co.uk/showthread.php?t=8945&page=3

This is the first I've heard of canibalism in varroa outside of brood cells but having talked to Peter in the past I've no doubt this information is comes from a good source.

Bcrazy, ignore the number of replies and check the views, this is a good thread with many lurkers and deserves to continue.
Keep up the good work !

 

[Bcrazy]

today is another day for the mite drop count.
I am now seriously thinking along the lines of it may NOT be the bees that are causing the damage to Varroa but the mites themselves fighting each other that is causing the damage. i would love to be proved wrong and find the bees are responsible for the mite damage but how do they inflict the damage shown?

 

[mandabow]

if bee's arn't capable of making these rips/dents etc, that doesnt 100% mean they are not responsible for them. They may have learned a behavior that can damage the mites in a non grooming way, like rubbing against a sharp rough surface or something similar. something wedging between the plates of your exoskeleton is bound to itch.

i'm of the opinion it's more likely to be something to do with the bees. very few animals but ourselves select for self detremental behaviour.. however it has been known.. and varroa has killed off a lot of colonies, maybe it has learned (genetically speaking of course) that there is no benefit to killing a colony.. much like the basis of this talk on germs. maybe fighting is their way of giving the bees enough of a break to survive to transfer varooa.


in the early stages of varoa spread a dead colony area would soon be recolonised by a new swarm who would pick up dead swarms varra load.. once wild pops are gone and we stop (some) of our swarming, varoa that kills its host colony will die in the colony as the waxmoth clears it out... varooa that don't kill their keepers get to become transmitted by drone movement, helthy hive produces more drones etc

 

[Bcrazy]

Hi mandabow
I think i get the generaliseation of your post as i have had to read it four times.
Could you tell me how the bees cause the removal of four of the mites legas from one side of the mite body. I just cant see it.
I have tried to dent the outer shell and it did dent easybut that is using a pin.
I have to admit i am not sure if a bee could inflict damage to a live mite . I hope to high heaven i am proved wrong.

Mo

 

[mandabow]

Hi mandabow
I think i get the generaliseation of your post as i have had to read it four times.
Could you tell me how the bees cause the removal of four of the mites legas from one side of the mite body. I just cant see it.
I have tried to dent the outer shell and it did dent easybut that is using a pin.
I have to admit i am not sure if a bee could inflict damage to a live mite . I hope to high heaven i am proved wrong.

Mo

sorry, dyslexic rambling/braindumps are my forte.. errrm i can try nd translate if you like...

as for leg removal, seems quite simple to me.. probably best explained with bumblebees ('cos the hairyness helps visualise)http://www.google.co.uk/imgres?imgu...1t:429,r:15,s:19&tx=54&ty=14&biw=1280&bih=581

see a bumble bee... it looks hair all over.. bu the exoskeleton is segmented, and the overlapping bits don't have hair on or they would not pass over one another smoothly. if you think of it like a suit of armor, there are joints that need to move or the bee would be ridgid.

you can get a better idea of how they move by watching this [ame]http://www.youtube.com/watch?v=J8Ey_tAqAwQ&feature=related[/ame]
see how the bands slide over one another.

now for varroa the best and easiest way to get bee blood is from larvae.. no exoskeleton to worry about.. most animals with exoskeletons grow and shed their skin from time to time leaving a vunerable stage while the new skin grows... bees don't give them this oppertunity, as they hatch fully grown.. however there are some biological advantages to drinking the blood of an adult bee.

1. the adult bee can feed more and produce more blood.. the brood is sealed at capping, you can only take a finite amount of blood from a larvae before it dies. if it's dead the blood is more difficult to suck, and ultimately goes off.. also killing the young means the colony will likely die sooner so you've done yourself out of a supply of food in the future

2. the adult bee moves around. bees don't have aheart as such, they have a pulsating tube that helps distribute nutrients during larval stage, but even then they need to move around as they get bigger in order to help shift it through their artery and back round to the digestive tract. being an adult they are not constrained by the cell and move wings etc a lot more, effectively pumping blood around.. this means the varooa once attached to the artery wouldnt need to suck so hard to get blood out, it will be delivered to them by the bees movement.

3. evolutionary wise, varroa who don't attach themselves to (drones i suspect, as bees tend not to enter eachothers colonies) bees don't spread to other colonies, and so as they kill their colony they are effectively seailign their fate too.. by surviving on a bee that leaves the colony they can hitch to pastures greener as their home colony wains and dies, thus ensuring their survival above other less mobile cousins.

4. eating form adult beed does less damage to the colony. no buckled wings etc theyre suseptibility to viruses is hightened in larval phases due to reduction in nutrition (as explained before) in presence of the mites.. the adults make up for feeding mites by eating more.


to get the the blood of an adult bee a varooa must either learn to chew through the exoskeleton, or nestle itself in the crack between them, and take a sip of blood whenever the softer skin like bits below become exposed.

this is a precarious position. if the bee contorts its body to reach into the depths of a flower the mite may be pushed off its footing and fall off, or may be crushed between the two edges of the exoskeleton.. if these are sharp it may cut the varoas exoskeleton. if say the legs get trapped in between the bees exoskeleton layers and the been knocks against something hard off come the legs, next time the bee stretches the other way then they can fall out of the gap.

bees can evolve a smaller gap or have the exoskeleton go down deeper to widen the overlap(negatively impacting flexibility) to make it harder for varooa to get to their blood.

or they can widen the gap and sharpen the edge of each segment to crush/slice more varooa as they can now get deeper into the gap between them. which is what i suspect is happening.

the grooming people see may be the removing of dead/dmaged mites from between the segments as they probably don't always fall out. gromming of fine mites too. but then they can just climb back onto another bee if they don't fall through a mesh floor to somewhere far enough away that they can't climb back.

Hope this make sence.. not based on any papers or reading i'm afraid, just my warped minds musings.


edited as well to add.. i don't think this is concious on the bees part. more that bees with sharper edges to their exoskeletons are the ones surviving, darwinian and such

 

[Bcrazy]

Did a mite count on the big wedding day i had to prioritise, no problem really.
As the song goes Aother one bites the dust.

 

[Bcrazy]

May 3 and its that time again for a mite drop count.
there were a few live Varroa this time so i wonder if that is an indication of the bees becoming grooming each other and nocking down the mites.?

Mo

 

[DanBee]

The theory is appealing but be careful you don't over-develop it. Also, your rationale is incorrect in a number of areas.

If we take the view that varroa, much like honeybees, die when they are worn out, then we would expect physical damage to be apparent in a proportion of dead specimens. Older honeybees exhibit tattered wings and hair loss, but I would rarely ascribe this to grooming/aggression/cannibalism. 'Wear and tear' is the far more reasonable explanation. In mites, some of this wear and tear may well be inflicted by the movements of the bees, whether normal activity or a conscious attempt to scratch an itch.

2. the adult bee moves around. bees don't have aheart as such, they have a pulsating tube that helps distribute nutrients during larval stage, but even then they need to move around as they get bigger in order to help shift it through their artery and back round to the digestive tract. being an adult they are not constrained by the cell and move wings etc a lot more, effectively pumping blood around.. this means the varooa once attached to the artery wouldnt need to suck so hard to get blood out, it will be delivered to them by the bees movement.

Your understanding of the circulatory system is incorrect. Dade's Anatomy & Dissection of the Honey Bee, or Celia Davis' Honeybee Inside Out would explain it clearly.

3. evolutionary wise, varroa who don't attach themselves to (drones i suspect, as bees tend not to enter eachothers colonies) bees don't spread to other colonies, and so as they kill their colony they are effectively seailign their fate too.. by surviving on a bee that leaves the colony they can hitch to pastures greener as their home colony wains and dies, thus ensuring their survival above other less mobile cousins.

You are overlooking robbing, drifting, and absconding due to imminent collapse.

4. eating form adult beed does less damage to the colony. no buckled wings etc theyre suseptibility to viruses is hightened in larval phases due to reduction in nutrition (as explained before) in presence of the mites.. the adults make up for feeding mites by eating more.

Chronic, Acute, and Slow Paralysis Viruses, for instance, target the adult stage with damaging effects. There are others.

The reduction in nutrition point is questionable; the transfer of virus material by the feeding of mites is more likely to be the cause as this bypasses the normal defensive mechanisms (digestive and cuticular). Mites that enter a larval cell feed on that larva for many days. Studies have shown that virus particles in the millions are needed to infect through ingestion, but only hundreds are needed if injected into the haemolymph. Have a read of something by Lesley Bailey (Honeybee Pathology, etc.) for the experimental evidence.

It has also been stated recently that some viruses multiply within the mites; rather than being a passive carrier they can be active incubators. DWV was the example cited.