If you take a colony of Italian and one of Corneal en and cross these, you have a hybrid, you also have a more aggressive bee than either of the other two. Does this answer your question?
Also the AHB came from the pure African breed "which is aggressive to begin with" crossed with the European bee, which in any one of the breed's in pure form is docile.
The African aggressiveness genes is dominate over the European gentleness genes.
This should not be that hard to under stand. If we want to rear queens we are surly going to pick our most gentle colony to rear a queen from, if it is also a productive colony.
If you have an aggressive colony in your bee yard that re queening doesn't fix, then you will want to move that colony far far away from your breeding grounds, If you are going to rear gentle strands.
I am also against calling these AHB's (KILLER) bees.
Any one who is allergic to bee stings can die from only one sting from a gentle strand.
We, the beekeepers should let people know some of these things. We are not like the Media, we are not in it for ratings.
Yes, we should not take the subject lightly either.
The question of whether they can adapt to cold climates, That answer should be simple. They have some of the European genes don't they? Who's trying to fool who?