Thanks for interest and info. A bit of web searching has revealed that there are 170 some Bt toxins. Of the handful of articles I have looked at, it appears that there are widely different toxicities to the various Bt GMO forms. I'm not sure I believe all the numbers. One study reported larval toxicity at hundreds of ppm and adult toxicity around 10 ppb. A 2007 EPA required study showed tox in the low ppb range. One has to look at how the research was done and compare that to bee behavior, etc. to know how likely the bees are to be exposed.
Results are mixed as might be expected, but with the great number of natural Bt toxins (~170) and the potential for unintended/unanticipated genetic variations caused by or related to the GMO insertion, it is like playing Russian roulette once the "cat is out of the bag"
Our impacts due to conventional pesticides pale in contrast to the risks from irretrievable genetic characteristics once released.
Below are a few of the easily found sites.