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