Cha(u)lk Brood...

[mbc]

I agree and most say the cure for chalk brood is to re queening with a more hygienic queen! We have exactly the same here. No mater how you look after your AMM"s black bees , wild bees or feral bees, whatever you want too call them, they get Chalk brood. Not bad bad, but enough to make you concerned.
!

Chalk is a bugger to breed out of natives, I've lost count of the lines I've let go out of my breeding efforts as some daughters would show susceptibility to chalk.
The spores are endemic and most/all larvae are exposed to them but it's only the susceptible ones that allow the chalk to take hold, it's mostly genetic but also environmental in that otherwise healthy larvae can be compromised by chilling or neglect and the fungus can then multiply.

 

[Michael Palmer]

The spores are endemic and most/all larvae are exposed to them but it's only the susceptible ones that allow the chalk to take hold, it's mostly genetic but also environmental in that otherwise healthy larvae can be compromised by chilling or neglect and the fungus can then multiply.

I agree with you to a point. And, I know nothing about your natives. But, I guess bees are bees. I think it's true that some stocks are resistant to chalkbrood. The disease never shows up, and no obvious problem with the brood pattern. But I think all stocks will have some degree of the hygienic trait, and some have such a high degree that if any larvae become infected, the bees remove it so fast that the disease never becomes contagious. So, the diseases never takes hold.

So if you would first do your selection process, identify your possible breeders, and then test these colonies for being hygienic. Those that test highest are your breeders. Chalk will be a thing of the past.

That's one way. Chalkbrood itself can be used as the marker for hygienic bees, by never breeding from colonies that ever show chalk. Works over time, but slower than the liquid nitrogen method. I've used this method, after buying very hygienic stock back in the 90s. My bees were rotten with chalk before requeening with hygienic stock. Disappeared in a year, and now, after selecting non chalk breeders since then, I almost never see a chalky colony. This summer, Cornell University tested my stock. 97% hygienic.

 

[mbc]

I've not found the time to use liquid nitrogen or pin killed brood assays but never graft from colonies with anything but an immaculately clean brood nest, with open mating chalk still seems to show up here and there despite years of efforts to get shot of it.