I've been encouraged to create a post to share with everyone on some of what I've been attempting to find and stabilize some mite tolerance and resistance in bees here in Central California. Given the time of year, it seems like a good day to start the discussion and start sharing what I've seen and garner the discussion on developing a pseudo breeding model that might be effective in a high density area of commercial bees. I'll try to keep it as chronological as I can and detail as best I can what's been done and what bees have been tried. I will preface, I will name names, describe my personal experience with said bees, and be as truthful and honest as to what I saw or am seeing. I also do not mean any disrespect to anyone I've gotten bees from as most or all of them have been good bees as far as typical commercial/hobbyist traits go but the main point of discussion will be how well they fared with mites.
Secondly, I will describe our landscape, it's fairly heavily used for mainly agriculture. I do have a few hives in an urban setting which fare somewhat better as far as forage goes. Typically though, our dearth can start as soon as almond bloom is over if there isn't much wild mustard or radish blooming. Where I keep the bees there isn't much fruit tree production either, so no cherries, plums or citrus, mainly almonds, walnuts, and pistachio, with almonds the only one being any value to the bees. Mustards and radish will carry into April if they're not sprayed out but then farmers start working their fields and planting. Mainly it's tomatoes, field corn, alfalfa, hybrid sunflower seed production, and some safflower. The alfalfa is rarely of any use to the bees as it's cut 6-8 times during the season and doesn't get to bloom very much or for any extended period of time. If I'm lucky, vetch carries into May somewhat and then hopefully I get some starthistle in June/July but it's getting very dry and hot by then as well. After that it's pretty much a dearth August - December depending on the weather and area, but where my bees are at, it's pretty slim pickings. Also keep in mind, there's 3 commercial yards within a quarter mile area with 30-40 pallets each yard. They are moved in and out for pollinations so they're not always around during the season, but typically they show up at the end of July and stay through January and might be around sporadically March - June.
In the end though, what's the goal of all of this... I'd really love to find some genetics that work well here in Central Valley California for resisting varroa mites. So far it's been very challenging as our mite pressure is very aggressive in terms of growth and virus pressure. Part of it has to do with lack of quality forage throughout the year though. I think the stress from robbing pressure, the heat in the summer, and nutrition take their toll, especially on the longevity of the lives of the worker bees. I do think there's a light at the end of the tunnel though, it may take some time to get there butI'm always up for a good challenge.
I'll post more as time permits, I'll give a little detail on my background and education then move right along into the bees of where I started and where I'm at now.