UC San Diego Study: Spread Of Africanized Bees May Be Good For Agriculture
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September 14, 2015 1:12 p.m.
UC San Diego Study: Spread Of Africanized Bees Is Good For Agriculture
Josh Kohn, professor of biology, UC San Diego
San Diego homeowners usually don't like to find beehives inside and as are in the backyard but the large number of so-called fair will be colonies here is just one of the ways San Diego shows unique relationship with honeybees. A new report from UC San Diego researchers finds the majority of honey bees we encounter in San Diego are Africanized. The spread of Africanized honeybees continues northward in California. Joining me to discuss the new be report is Josh Kohn he's a professor of biology at UC San Diego who co-authored the study. Into the program.
Most of what we've been talking about the media, in terms of bees is a phenomenon of colony collapse. But that's not what your study was about. What was your focus?
I focus was on the frequency and the extent to which Africanized bees have invaded the state.
And so how likely is it that the be used the flying around your roses in the backyard here in San Diego is an Africanized Honey be quite
It's very likely. Probably at least two thirds of the be the fly around are Africanized. That does not mean you're under any danger when you see a single be flying around in foraging it's the workers and they're not particularly aggressive it's only if you disturb the high that there could be a problem.
Know if you could, give us a quick background on the honeybees from Africa and how they got here.
They were brought to Brazil several decades ago to try to create honey before that would be more successful in the tropical environment some of those acculturate escaped and begin hybridizing with European honey bees in Brazil and have since that time spread both cell to Argentina and North now the California.
And do African honeybees look any different than the European variety?
Even an expert looking at them cannot tell one from the other. You have to measure them and even then there's a lot of overlap in her size characteristics. You need genetic tools.
But from your previous question there's been a lot said about how they act differently. Has that been exaggerated do you think?
Certainly it has. The ID -- idea killer bees which a bit in the movies is an overstatement. However they are decidedly more aggressive than the European form that was commonly in the state prior to now.
When you say more aggressive, what he mean by that?
If you disturb a hive, they will mass more frequently and attack for a longer duration than the European honey bees. On the other hand, they have some potential advantages. They seem to be more resistant to some of the diseases that are causing problems for honeybees and crop pollination.
Now your study tracked the advance of the Africanized honeybees into central California. How far north have they actually gotten to?
As far as we could detect they've gotten to about 40 km south of Sacramento it -- Sacramento in the Delta region. They don't go quite so far along the coast, they tend to like hotter areas and areas with warmer winters. They extend farther in the Central Valley and very Eastern be area than along the coast.
And how do you do that kind of a study? Do you go along a pickup honeybees as you go?
It was a great road trip with my master student and myself. We would drive along and every 30 or 50 miles when there was a patch of flowers that honeybees would like we would jump out of the car, and that we honeybees and preserve them and bring them back to the lab for genetic analysis.
And that's the only way you can tell?
Do you expect the Africanized honeybees to go much farther north?
Nobody really knows. There's been predictions made based on how far south they made an Argentina and some climate modeling to figure out how far they would go. There a bit north of predictions but the predictions are not too bad in part of the reason their farther north of those predictions are the climate has been warming. And our study it was the warmest year on record when we did our study and it may be that we found honeybees that are farther north and they can really managed to stay in the winners should we get some quote unquote normal winters.
The when the Africanized bees arrive in certain locations, they don't just kill off the honeybees that are already there. These must be hybrid bees?
That's right they been hybridizing with European honeybees the whole way from Brazil to California. After the hybridization wave moves through, what you find is bees contain a mixture of genes from European and African sub species with the majority of the genes being African and the minority being European. That's likely what we have here now.
Because the African genes are dominant.
It's not really dominance, it's just there selected for. There are traits of these African honeybees that outcompete the traits of the European bees. Those traits are caused by genes and that is why their genes tend to predominate. One of those traits is aggressive behavior that there may be many other traits that are of utility such as disease resistance that might cause these be the actually be more resistant to the kinds of colony collapse that we see in managed hives. I should mention another thing which is most of the bees that we find in San Diego County, we can show were in fact not from beehives in the classic sense of a white box someone is managing but they are feral bees with a belt hives and people sees, three holes, or cavities in the roc. The great majority of honeybees you see out foraging anywhere in the county whether it's urban or world, backcountry are in town are these feral Africanized honeybees.
What you call the feral?
Because they are not managed by humans. Just as we because that's call a wild sheep of feral sheep, that's why we call them feral.
Are the introducing Africanized bees into their managed bees?
We have samples from beekeepers and have found low frequencies of Africanized bees. In some cases, beekeepers do. The local beekeeping community, their rules are to read Queen with the European Queen periodically to prevent the spread of African is a sure bet many beekeepers are also the people that will moves ones from your eaves. Sometimes they will keep those swarms and put them in a hive and keep them and sometimes those are in fact Africanized.
The fact that you have found these hybrid bees so far north, into what is really the heart of California's agricultural area, do you see this eventually changing California agriculture or how we use honeybees and agriculture?
Africanized bees are as good a pollinator as European honeybees are. The only problem is they are a little harder to manage. Throughout Central and South America, where farmers are not going to pay to raise European Queen they have to buy commercially they work with Africanized bees and it's just a matter of changing your husbandry practices and being more careful. The big problem with California agriculture is we import these I literally the 18 wheeler truck load in order to pollinate crops like almonds or apples or squashes and things like that. The Africanized aggressive Africanized bees and hives on the back of an 18 wheeler, it's not going to work.
That's not an 18 wheeler you want to be driving.
That's a problem. On the other hand for the smaller farmers and people everywhere, for pollination purposes, the Africanized honeybees are just fine in the workers are not aggressive when they are away from the hive. If you are near a hive, and you're using power tools or something then something that happened.
Apparently honeybees are not native to San Diego yet they seem to drive.. But with a first introduced?
Honeybees are in fact not native to the New World. There were no honeybees in North and South America before Europeans arrived. In California they arrived apparently just after the goldrush. A man named Harbison after her room Harbison Canyon Road is name was the first person to figure out how to get beehives transported around the horn on schooners and arrive alive in San Francisco. He was apparently able to sell hives for $100 each. Back in the 1860s which is a considerable sum. He moved his operation from near Sacramento to set -- San Diego and when the transcontinental railroads went in, he sold home honey and one or 2 pound lots back to New York and Chicago with honeybees foraging here a native plants.
That's a point to make to because even though they are not need update pay -- play a tremendously important role now.
If you go out in the chaparral when it's blooming and look at what's visiting flowers, honeybees account for approximately 90% of floral visitors to most of our native shrubs. They are performing an incredible amount of pollination services not just the croplands but native plants.
I'd like to talk about the Africanized honey bee and their aggression. There was a construction worker killed just recently approaching on live in Riverside. Events like that, understandably get a lot of publicity. You just mention using power tools. Just using power tools around the hive with these hybrid bees. They are actually much more dangerous to approach in some sort of way that the bees are going to take is threatening in some way.
Yes. Once threatened, they keep that the attacking or fending off what they perceive as a threat for much longer and overmuch big distances in the classic European honey be which is been bred to be more docile by managers.
Do you see the hybrid bees becoming more docile or do you see just more bees becoming more Africanized as time goes on?
It's hard to measure aggressive behavior. It's hard to do science on. The experience for all of this hybridization from Brazil to her in California has been the aggressive trade remains even after all of this hybridization. The only take a message is it must be selected for it provides an ecological advantage that has caused the two purses.
And to just make this clear, most of the feral bee colonies here in San Diego, most of the hives you will find under the eaves are out in the backyard somewhere have a majority of Africanized bees and so people really should be a little bit more cautious than they been in the past.
They should be cautious but not overly worried. In San Diego, we have a lot of outdoor activities you can enjoy and there were sharks, there are rattlesnakes, there are Matt Lyons, and there's also Africanized bees but it should not prevent you from enjoying the outdoors.
With further study of these hybrid bees by studying their DNA, what do you want to find, what have you looking for?
One thing of interest would be to figure out which parts of the genome are from Africa and which parts are from Europe and whether those are consistent all the way along from Brazil to hear. And then my genes underlie those regions in the genome. There is a sequence genome of the honey bee and the Africanized form of the honeybees so we can start to piece together which parts of the genome come from which cotton and and then hopefully, we can find regions of the genome the cause aggression and other regions that might be related to disease resistance and so we might be able to in fact read a better type of honey be that would be both docile and disease-resistant.
I've been speaking with Joss counties a professor of his head of the study on Africanized bees in California published in the Journal +1. Thank you so much.
But sure to watch KPBS evening addition at six that 30 tonight. -- 6:30. Thank you for listening.