"The genetic makeup of these "gentle" bees bears an unmistakable Africanized stamp. Yet somehow, in less than 20 years, they have lost the extreme defensiveness that we have come to expect of killer bees. The Puerto Rico beekeepers are using local Africanized bees for their industry and do not report problems with highly defensive behaviour"
I go into detail on the background and details in my FAQ "The Truth About Africanized Bees".
However, the basics is this:
Genetics have been diluted over the last decade and 70% of SoCal feral populations have at least 10% Africanized genetics. However, that also means that they have up to 90% of European genes. The dilution of genetics has contributed to bees with Africanized genetics to become docile over time. They CAN and SHOULD be given a chance if a beekeeper specializing in feral bees decides they are manageable.
What does the San Bernardino County Dept. of Public Health recommend? The safe rescue and relocation of feral colonies versus extermination when possible.
WE RESCUE FERAL COLONIES! - (909) 660-3072
Gentle Africanized bees on an oceanic island - http://onlinelibrary.wiley.com/doi/10.1111/j.1752-4571.2012.00252.x/f
San Bernardino County Africanized Honey Bees Fact Sheet - http://www.sbcounty.gov/uploads/dph/dehs/depts/vectorcontrol/AfricanizedHoneyBees.pdf
Range and Frequency of Africanized Honey Bees in California (USA) - http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0137407
Are Killer Africanized Bees Really That Dangerous? - http://www.bbc.com/earth/story/20151123-are-killer-africanized-bees-really-that-dangerous