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Wednesday, April 1, 1998 Published at 21:16 GMT 22:16 UK



Sci/Tech

Scientists take sting out of killer bees' tail
image: [ Killer Bees: a threat to North America ]
Killer Bees: a threat to North America

Scientists studying the march of 'killer bees" across North and South America have discovered a "mean gene" which they believe makes them attack humans.

The researchers found that bees carrying the gene were far more likely to sting humans and animals than their more placid European cousins.

And the team behind the findings believe they can use their results to track down queen bees carrying the genetic marker.

Invasion northwards

African honey bees, dubbed killer bees, have been migrating northwards from South America since they were first introduced to the continent and bred with European bees in 1956.

They became feared after they were found to attack 20 times faster and leave eight times more stings than European bees.


[ image: Killer bees are travelling at 300 miles a year - and have reached Texas]
Killer bees are travelling at 300 miles a year - and have reached Texas
They first began appearing in numbers in the US in the 1990s and there have been fears that they could devastate crops and force people to flee towns.

Scientists believe they are flying 300 miles further northwards every year and the sound of a swarm in flight has been compared to hearing an aircraft engine.

While they are not exactly the deliberate killers of popular imagination, they are far more likely to attack in self-defence and cause either serious injury or fatalities.

Dr Greg Hunt of Purdue University in the US said: "In one study in Venezuela, the researchers found that these Africanised bees attacked a target 20 times faster than European honey bees and deposited about eight times as many stingers.

"When you see this for yourself, it's quite striking."

Genetic discovery

Dr Hunt's team bred the killer bees with European bees in an attempt to establish a genetic link to the attacks.

Some of the offspring inherited genes from the killer bees which appeared to affect their behaviour.

"We were able to associate particular DNA markers that were inherited from the African bees, and were associated with increased stinging behaviour.

"We would wave black leather patches in front of colonies of bees for one minute and measure how many times those bees stung that patch."

Writing in the scientific journal Genetics, Dr Hunt says the team identified the location of five genes linked to agression.

One gene appeared to control the tendency to sting - the mean gene.

Dr Hunt said: "If we put worker honey bees on an electric grid and slowly increase the current until they sting, we find that Africanised bees sting at much lower current than European honey bees.

"This one gene on one chromosome has a significant effect on both the behaviour of whole colonies and individual honey bees."

The gene's discovery means that scientists could have found a way of screening queen bees to keep a track on the march of the species.






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