One report I read not that long ago was reporting that africanized honey bees, those being a mix of the western honey bee and the african honey bee, tend to assume the traits depending on the climate.
As the AHB are in warmer climates, the Africanized genetics take over. However, the more they were pushed into cooler climes, the European bee genetics began to take over. It was noted that the bees became noticeably more docile the further into cooler climates they were.
The report I read was older and If I recall, quoted frequently from the scientists who did the South American studies which brought the African bees there to begin with.