Quite so GBH, (GBH??), most French bee keepers treat for varroa even though the evidence is that in more naturally managed colonies there is no substantial difference between treated and untreated colonies, in fact keepers that I know that treat often have high winter losses, (up to 20% is fairly normal and 40% isn't that uncommon - I think the average last winter was just under 30% but that's second hand info). Last winter I had no losses which was
and I've never had a varroa related loss, which doesn't mean that I won't.
I have had colonies that have "died out" due to Queen loss for what ever reason, (over winter or failed mating as you would expect), but never starvation or disease, which again doesn't mean that I won't.
I have collected swarms that have died quickly - dysentery for example, (I have a quarantine site for swarms that aren't mine).
Of course there may be fewer "feral" colonies in the UK because people don't leave them alone.
Initially when varroa arrived in France, (1982), there were substantial losses in both captive and natural populations, however this also coincided with the use of two controversial insecticides, Regent and Gaucho.
Snippet from an article I wrote in 2008.
Two of these insecticides known respectively as Regent (fipronil), and Gaucho (imidaclopride), were in used extensively in France to coat the seeds of sunflowers and maize before sowing. They have a systemic action and enter all parts of the growing crop including the flower, pollen and nectar. When abnormal bee losses were first noticed in the 1990’s the finger was pointed at these products and they were banned from being used on sunflowers in 1999 but it wasn’t until 2004 that the ministre de l'agriculture français Hervé Gaymard announced that the use of Gaucho for the treatment of maize seeds would be banned.
There are still arguments as you would expect and probably know regarding this group of chemicals and I wouldn't try to suggest that varroa didn't have or for that matter doesn't have an impact on bee colonies but it may be in conjunction with a combination of stress factors. Equally it may be that the surviving colonies that haven't been messed with too much can cope better with the situation.
Chris
