Can We Domesticate Africanized Bees?
Africanized honey bees were first detected in the Southern California area about 20 years ago. When I began beekeeping in this area, I was quite concerned about the Africanized bee because of the traits described in the press and in the book "Africanized Honey Bees in the Americas" by Dewey M. Caron (2001). Caron reported that the Africanized bee had a wide defensive perimeter and would generally attack any animal or person who came within that perimeter. And they would attack "en masse" with hundreds of bees attacking the person or animal.
He also reported that Africanized drones were better able to mate with virgin queens (such as European queens) and that the African genes would predominate in the offspring. So a European hive that superseded its queen was likely to have Africanized workers when the new queen returned to the hive and began laying.
Additional reports were that the Africanized hives would swarm much more often and would abscond if conditions became difficult in the hive.
Paints a pretty dim picture, doesn't it?
When I began keeping bees in this area, I encountered a number of beekeepers who were keeping feral bees. That is, they recovered swarms (perhaps hanging in a tree), or did cutouts of hives in a building. Now, some of these bees must have been European bees, but the majority almost had to be Africanized. Why is that, you might ask?
The answer is varroa mites. European bees generally cannot coexist with varroa mites, but the Africanized bees can. From what I've heard from experts, the Africanized bees will groom mites from each other, and they can detect a varroa infested brood cell and will clean out that cell, stopping the spread of varroa in that hive. The European hive will eventually be overwhelmed by the mites and the hive will collapse. So if the bees were surviving in the wild (feral) they had to be able to coexist with varroa. And every hive is infected with varroa.
If a beekeeper hived a swarm or cutout from a hive that had been feral for a couple of years, that hive almost certainly had the ability to coexist with varroa. Some of the swarms may have come from European hives kept by a backyard beekeeper and would not have the ability to coexist with varroa. The beekeeper would lose those hives if they were not treated for varroa.
But some of the things said by Caron don't seem to hold up to logic. The Africanized bees coming up towards the US had been mating with European bees for many years. While the African genes may have predominated, the European genes had to express over the African genes sometimes. So the "Africanized" bees that made it to the US had to have been genetically diluted.
Once they got to Southern California, they faced other evolutionary pressures. Southern California is DRY for most of the year. Wild areas see a bloom during the winter rainy season but for perhaps nine months of the year there is not much nectar in the wild lands. To survive, bees must locate in the urban areas where gardens are irrigated and nectar (and water, for that matter) is available.
And in an urban area, any bee hive that had a wide defensive perimeter would be exterminated shortly after they stung one or more people. Bees in an urban area need to "lay low" and not be noticed to survive. Africanized bees that did not have a wide defensive perimeter would be selected over more defensive ones. I often walk by a decorative stone pillar in a neighbor's front yard that has had bees in it for years. I can walk right up to the entrance of the hive and the bees ignore me. Those bees can coexist with varroa (or they'd be dead by now) and they're docile enough to not attract attention to themselves. The post they're in makes it impossible to do a cutout or I'd had taken them by now.
Excessive swarming, especially late in the year swarming, would not be a successful evolutionary strategy in Southern California. First, there are not many cavities which will serve as a hive. The bees often wind up in utility boxes, especially cable TV boxes and water meter boxes. The water meters have to be read monthly so the bees that set up housekeeping in those boxes are usually exterminated fairly quickly. Also, late swarming does not give the bees much time to gather sufficient stores for the winter so they often starve. I have collected hives from cable TV boxes that had been there for a couple of years. I guess those boxes don't require much attention from the cable TV company.
Next, we now have beekeepers who are working with feral bees. The beekeeper who encountered an excessively defensively hive would likely exterminate it. After all, the hive did not cost the beekeeper anything except time so the loss would not be expensive. The beekeeper cannot take the risk of owning an excessively defensive hive and those hives are a nuisance for the beekeeper to deal with.
Finally, the Africanized bee is adapted to a hot, equatorial climate and does not tolerate colder winters. That's why the Africanized bee did so well in South America. But they were halted by the climate in Patagonia and will be limited in their spread in the US because of colder winters. While Southern California does not get severe winters, neither is it the equatorial climate the bees favor. Southern California is just not as hospitable to the Africanized bee as South America. This may result in bees that have more European genes being successful in feral hives in this area.
I've been told that the genes that cause defensive behavior in the Africanized bee are different from the genes that cause varroa hygienic behavior. If true, we should see "Africanized" bees that are more docile while also being able to coexist with varroa.
Our challenge, therefore, as beekeepers of feral bees, is to keep up the pressure on feral bees, exterminating excessively defensive hives and splitting those which are docile and can coexist with varroa. It's going to take a number of years.
[Update 12/30/2017] Researchers have found "gentle" Africanized bees in Puerto Rico (PR). You can see an article about it here. It appears that the bees came to PR in the 1990's and have replaced the European bees on the island. The Puerto Ricans apparently have been exterminating the more defensive hives of Africanized bees, leaving only the more docile hives. PR is a bit special because "new" Africanized bees cannot easily come to the island to refresh the Africanized genes. But it shows that if we put pressure on the Africanized bees, by destroying the really defensive hives and encouraging the more docile hives, we have a chance of developing bees that can coexist with varroa, while being docile.