This whole debate is reminiscent in my mind with that which raged over the impacts of smoking and health. Whilst the focus was on "does smoking cause lung cancer?", with much to and fro debate and research pointing both ways,  people were succumbing to accelerated rates of heart disease, stroke, peripheral vascular disease etc which we now know was related to their smoking habit. Sure, some individuals did not succumb to any of these disastrous outcomes after a lifetime of smoking, but they indeed were the lucky ones. For most people suffering these problems, the health professional clearly attribute these to previous smoking history.

And so it is, in my mind, with agrichems exposure and bee health. Some colonies suffer, and indeed succumb to, nosemosis, varroasis, impaired digestion of pollen, inadequate foraging success, and perhaps even impaired homing ability. Agrichems of one kind or another exacerbate all of these problems, and the mechanisms by which they do this vary from intrinsic, such as compromising the bees immune system, to extrinsic, such as eliminating flowering weeds as a food source. But they do this. And whilst we can argue about field relevant doseages, the fact remains that some beekeepers lose their colonies big time and others don't, with a range of scenarios in between. As a group, I see many of those who don't, refusing to accept or understand, that those who do, have a case. I find that sad, and frustrating.

Remember that, just as some within the human population can withstand the proven toxicity of tobacco smoke inhalation, in all probability due to genetic advantages, so it is with bees. Not all colonies will have the same susceptibility. Given the narrow genetic variation which inevitably occurs in many managed apiaries, it is well within the realms of probability that some beekeepers will experience a large scale problem and others not, when their bees are exposed to the same agrichems, perhaps even at the same "field relevant dosages".

The big picture implicates agrichems. I have no doubts about that anymore.

PeterD
in Western Australia, where the same variations exist.

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