Acarine susceptibility

[Apis]

"Now the following fact is very important to us beekeepers. It is only into very young bees that these mites penetrate. ...it is an ascertained fact that bees after five days from emergence are immune from attack by A. woodi".

Only source I have on this, any comments?

 

[Norton]

Hello,
Bright yellow Italian bees seem to be more susceptible to acarine than most other strains. The New Zealand yellow bees are susceptible and this is probably;y the reason that Carnica material has been imported into NZ recently in an effort to improve things.
Best regards
Norton.

 

[BKF Admin]

Norton,any idea what country is supplying NZ with the Carnie's?

 

[Norton]

NZ imports of Carnica semen

The semen was imported from Austria and Germany.
Norton

 

[Apis]

Not quite the point chums, are the girls immune to acarine after five days?

 

[Norton]

The resistant ones are immune all the time!

 

[Hombre]

Ha ha, Slowly we are getting there. . . How about the Italian bees that appear to be particularly susceptible, are they resistant after five days old as Apis asks, or do we not know?

I think that Apis feels he is getting political answers that avoid the direct question.

What is the nature or form of resistance, increased control of the airway entrance or smaller geometry precluding invasion?

 

[Hivemaker.]

The mites must invade a bee that is younger than 9 days old or the spiracles (air openings) will close and the mite will be unable to enter the tracheae. Various methods can prevent tracheal mites from identifying and invading young bees, leading to the death of the mites.

 

[Apis]

Thanks for the responses, you've all helped in a way. My interest is in the development of Acarapis from a seemingly harmless (possibly exoparasite) into the scourge of the black bee during the 'Isle of Wight disease' epidemic. My understanding is that the hardening of the setae that surround the spiracle (after 5 days) prevents infection. I also understand that the mite is a 'tight' fit.

All this makes me wonder how much of the change from irritant to pathogen is connected with cell size and the introduction of 'imprinted' foundation in a cell size that many now feel was incorrect. Do some 'oversize' bees from an alien environment really exhibit immunity or are their setae modified (maybe to keep out the dust of a hotter environment) and therefore offer non-specific resistance to the mite. My own interest is in small cell foundation, which short of a 'top bar', intuitively 'feels' the way to go.

Most tell me that my enquiries are irrelevant as acarine isn't a problem but it was and are we just brewing yet another issue for the future?

 

[Norton]

Hello,
I think that resistance to acarine exists in most European bee populations. An exception to this was A.m. adami from the island of Crete as this ssp was made extinct by acarine. It was a quite a large bee according to beekeepers who have been keeping bees for 30+ years. The susceptible types will of course soon die out with the resistant ones surviving and reproducing and adding their genes to the gene pool. The problem in the UK and in Crete came about because there were isolated populations on an island with no past selection pressure to develop resistance and when they became infested with acarine, disaster struck.
If you have been reading about the Lusby experience with small cell and acarine, keep in mind the above remarks as the small cell might have nothing at all to do with it as they bred from their own survivor colonies and as they are in remote areas it was possible for them to get matings between resistant colonies.
Food for thought.
Best regards
Norton.

 

[Apis]

That's great, thanks Norton. I take it therefore that you understand that 'reststance' is a genetic response to the problem. My understanding of Darwinian evolution is that physiological change is the net result. Do you believe that the size of the spiracle might be involved with the immunity?

... and while I'm aware of the 'Lusby experience', it was good ol' ROB Manley that got me thinking about it.

 

[Norton]

Hello,
Yes I think that the size of the spiracles plays an important role in acarine resistance. I have a paper somewhere here, amongst hundreds of others, with some nice photographs showing differences in the spiracles in susceptible and resistant stock, unfortunately it is in Greek so not much use digging it out and sending it to you unless you can read modern Greek.
I was also told years ago that it is the hairiness of Buckfast bees which gives the resistance. Maybe there are several different characters that play a role.
Best regards
Norton

 

[Apis]

Cheers Norton,

Very helpful.