I use Top Bar Hives. For my first two years I used Apilife Var, oxalic acid etc and basically, there was a varroa problem each year. So at the start of this season I decided to clench my teeth and avoid miticides, since I knew of a few examples of natural beeks developing varroa resistant bees by the Live And Let Die strategy. And there’s been a thriving feral colony in a neighbour’s roof nearby for 5 years. So it’s obviously possible.
So as we near the end of this season, I find the varroa counts are around 50/day and rising, despite a sugar dusting a couple of days before the last count. So I suspect that this strain of bee – originally Buckfast, probably just half Buckfast genes by now – have become used to someone else sorting out the varroa, and will never get the idea that they need to do something themselves. Reading around, the population dynamics of varroa are such that you can get away with non treatment for one season, but if they start off heavily infested next season, the mites will chew through the colony in no time. Unless they develop coping mechanisms, and this lot seem clueless.
This is especially frustrating as the hive 2 feet away contains a cast given me by Gareth, descended from a hive which has not had varroa treatment for 5 years, and it has a drop of one per day. Which shows that it is the bees, not the local area that is the problem.
So I’m wondering what I can do to help these wimps get a handle on the problem. The most obvious is better temperature control. Now the main nectar gathering / evaporation period is done, ventilation isn’t as big a problem, so I have sealed the bottom of the (mesh floored) hive. This might enable them to cook varroa to a point where they stop breeding.
I will sugar dust, but I gather this isn’t really effective, it just knocks phoretic mites off and doesn’t get the ~50% sheltering in cells – and due to some unknown reason, possibly less competition among the remaing mites, their breeding rate is almost unaffected. So sugar dusting is more a cosmetic thing than a practical solution.
I don’t want to lob an essential oil like thymol in there. I reckon just because a chemical is “natural” doesn’t mean it doesn’t upset the hive balance, for example the microbial microfauna. That’s just blind meddling; even though there’s evidence it stimulates chucking out of substandard brood, there’s little research on its other impacts. Anyway, brood laying will be dwindling now.
I would welcome any other ideas about how I can improve the hive environment to maximise this colony’s chances of dealing with the varroa themselves.