As a reminder to all, feelings do not count, we work in reality, my feelings are that hundreds of bee hive should not have died this winter, they did! -LSPender
I called it a "gut feeling" because I did not have empirical evidence at hand -- and had not heard of, nor had I seen, any empirical evidence of a test involving Bti directly tested on honey bees. After talking to some of the scientists who work on these projects (isolating strains of Bt to use against specific pests), I understand that the strains selected for use are screened against a panel of insects, and honey bees are on that panel. Honey bees are used because they represent a different order of insects (Hymenoptera) than are often targeted by Bt, they're readily available, and they are directly of economic concern (although in a different way than pests).
In the tests of Bti, honey bees showed no effect from exposure. So, could the proteins have some chronic effect on honey bee larvae? Possibly. But they might be exposed to those same proteins whether humans use Bti in some standing water and workers collect water from those pools, or whether workers naturally encounter Bti (this is not a "man-made" bacteria, after all) and unintentionally bring some back to the hive.
The information we have demonstrates that Bti does not harm honey bees.
MichaelW -
Some of the scientists confirmed that at least one serovar of Bt has been isolated that kills hymenopterans; some plans may be in the works to use it against sawfly (actually a type of wasp) larvae, although no one would state that specifically.