> it's more likely for the undesirable genes to be removed if the entire hive is euthanized.
Yes, removing the genes is needed, but that can be done by killing the old queen, waiting a day then putting in a caged queen of known good genes. There is no need to kill the hive that I am aware of.
Requeening to correct temperament is part of beekeeping and killing the hive seems extreme. It is also wasteful of the equipment and comb because depending on the method used it won’t be able to be salvaged.
Killing hives is generally done by pouring petrol in the top then sealing the hive up, and is seen as one of the more humane methods. However I’ve only known this being done for American Foul Brood, not for temperament.
The improved temperament sometimes happens almost instantly, but is generally over a about a month as the workers die off. The total lifespan of a worker is only about 6 weeks in midsummer.
I keep bees, but in New Zealand an aggressive colony is a lesser beast than an africanised monster. I hope I’m missing something (eg what is africanised bees reject new queens, but I can’t find anything suggesting this is the case).