Cory Stevens lives in southeast Missouri. There are some hives of hobbyists some miles from him. A larger beekeeper is 7-8 miles from him, but he uses Cory Stevens’ queen cells.
Started with resistance traits
Cory Stevens ceased treatments for Varroa mites in most of his then 20 colonies 8 years ago. 6 years ago the number had grown to around 45 colonies. Then a few got some formic acid. Then no more treatment. When he stopped treating he had acquired queens of different origins with resistance traits, VSH from Tom Glenn and Pol line Hygienic Italians crossed with local ferals.
Low winter losses initially
Initially he had very low annual losses. He has brought in new stock every year besides breeding from his best lines. This hasn’t been good for the development of his stock so he has stopped that and will focus on selecting from his own best colonies. He will evaluate the need for bringing in new stock again later.
Winter losses has always been lower than average nation wide. But the last years it has reached 30%.The winter of 2014-15 he lost 60% of 95 wintered. 45 of those (47%) were too small 5-frame nucs. The winter was severe and all of those nucs died. He says it was his fault, not the bees’. The winter losses 2015-16 will be much lower, it looks like cose to 20 %.
Initially some viruses
In the beginning when he saw more than a few bees with crippled wings (DWV) and K-wings (KWV) two different viruses, followers of Varroa and Tracheal mites respectively, he requeened those hives. Today he never sees any crippled wings. A few K-wings can be seen.
Removal of infested drone brood developed
Initially he didn’t see removal of varroa infested drone brood by the bees, only Varroa infested worker brood (in which the mites have offspring – VSH). But after breeding from the best survivors without any treatment he has seen this trait developing. He thinks that’s good as Varroa prefer drone brood and should continue doing it leaving as much worker brood as possible alone.
He has developed his stock to remove Varroa infested drone brood. It has simply turned up when breeding from the best survivors.
He doesn’t use small cell combs, but standard rite cell foundation. He does use screened bottom board on several hives, but he doesn’t think they contribute that very much to Varroa control.
This season he will check natural downfall to look for the percentage of mutilated mites. He will also be utilizing liquid nitrogen to test for hygienic behavior for breeding candidates. Some of his virgins will be inseminated with semen from ankle biters (mite ankels) from Purdue University to test if this will contribute to his stock. He will also put out more swarm traps to hopefully catch feral swarms.
Cory wintered 120 colonies last autumn. The goal now is adding 25-30 per year until he reaches 5-600. Then he will “retire”.