Re: Parasytic mite syndrome vs sac brood vs sac brood?!
Sacbrood is caused by a virus, Chalkbrood is caused by a fungus, and I know of no treatments that can be given to combat them. Strong colonies headed by hygienic queens , in full sun, and on stands that puts the colony 6 to 8 inches above any damp grass or earth are good management techniques that help prevent both diseases.
Both of these diseases kill the brood in the same stage, when the larva has been capped, is laying out straight in the cell, but has not changed into the pupal form.
Chalkbrood causes the dead prepupa to become chalky white, with the head dark. The fungus grows and the dead prepupa swells and fills the cell, and then dries into a "mummy" that will turn a grayish black. The "mummy" is hard, and the bees remove them and dump them the hive entrance.
Sacbrood turns straw colored when the prepupa first dies, then it turns brown and the skin forms a water filled sack that is tough enough that the prepupa can be removed from the cell. The head of the prepupa will be turned up, and will be darker than the rest of the prepupa.
The Bee Parasitic Mite Syndrome causes brood to die in all stages, and in my colonies, all stages were present at the same time. Dead larvae in the C stage will look like EFB, dead prepupa will look like AFB but will not rope out when stirred with a stick, and there will be dead pupa in all eye color stages. The colony will have high mite counts and mite poop will be seen in many brood cells. Dead pupa in the colored eye stage is a clue you can't miss, this is not present in Sac or Chalkbrood, or in AFB.
42 + years - 24 colonies - IPM disciple - Naturally Skeptic