Killer Bee Attack
Are Africanised Honey Bees really the Killers they are Portrayed to be?
Killer bees have terrorised North and South Americans since their accidental release in the 1950s. For years, scientists have studied killer bees in an attempt to understand them and stop them in their tracks. Is it possible to take the sting out of a killer bee?
In summer 1994, Kent Griffith was driving out of Tucson, Arizona to his country property. His neighbours had called to tell him that recent storms had caused some damage to the property. What Kent didn't realise was that these storms had also disturbed a colony of bees on the property, leaving them in heightened attack mode. Any movement or vibration can trigger a killer bee attack.
With the bees already angry, Kent was walking in to real danger. While clearing fallen trees with a chainsaw, Kent was attacked. He recalls "I was working on the tree with the saw when, suddenly, I felt a few bees which I swatted. Almost immediately everything went black with bees and the noise was tremendous. The bees were stinging my face, stinging through my clothing, I couldn't see. I was trying to brush the bees off. They were in my mouth, my nose, my ears and seemed to be increasing by the second. After what seemed like an eternity trying to brush he bees off, I realised that I had to run away. I ran for the nearest door which, unfortunately, was around the back of the house. I ran inside, closed the door but I was still black with bees. It was the most frightening thing that has ever happened to me".
Despite multiple stings, Kent survived. 500 bee stings is equivalent to a rattle-snake bite. Thousands have died.
Los Angeles, California is best known for it's boutiques, movie stars and sandy beaches. But the same sunny climate that attracts the tourists has drawn millions of killer, or Africanised, bees. They have now infiltrated all of Southern California.
Robert Saviskas of the L.A. County West Vector Control reports "Presently about 60% of all the bees in L.A. County are Africanised. We project that with two to three years it will be 100%".
Wherever killer bees have gained a foothold, the emergency services have had to learn how to deal with them. In the past, insect removal companies dealt mostly with mosquitoes, now it's killer bees. The biggest problem is telling the Africanised killers from normal honey bees. In Los Angeles it has taken a specialist agency to combat the killer bee invasion.
Robert Saviskas: "During the year 2000, we received over 6,000 calls concerning Africanised honey bees. We actually removed swarms, or hives, from about 3,000 of those locations".
A Massive Wild Bee Hive
The bee removal team receive a call about a possible hive on a derelict plot in L.A. What they discover is astonishing. The hive is at least one metre tall, weighing around fifty kilograms. It is a solid mass of buzzing bees. The trick is deciding how to remove it. If these are killer bees then one wrong move could prove fatal.
The team manage to secure the nest, after carefully removing the surrounding branches of the bush that had encased it, by lifting a large plastic bag around it to seal bees and nest together before cutting the supporting bough. The whole bag was taken back to the lab where it was frozen before opening. Tests showed that most if not all of the bees were Africanised.
Originally from Africa, killer bees quickly overcame the challenge of reaching the U.S. They were brought to Brazil in the 1950s to boost honey production, but a mistake allowed some bees to escape and the killer bee legend was born.
Professor Francis Ratnieks from the University of Sheffield notes "The killer bee was brought over from South Africa to use in a breeding programme to breed a better bee to use in tropical conditions".
Since they crossed the U.S. border in the 1990s, killer bees have continued to advance. They crossed first into Texas, then three years later into Arizona. In just 13 years, they've colonised every state bordering Mexico. They've also reached Nevada, The US Virgin Islands and Puerto Rico.
What is it about the Africanised bees that makes them so successful and so deadly? Their most obvious strength is self-defence. In Europe, bee-keepers have bred their bees for centuries to make them easier to work with. The result is plenty of honey and more good-natured bees. This is just not the case with the bees from Africa.
Dr Eric Erickson
Dr Eric Erickson the Director of the Carl Hayden Bee Research Centre explains "The bees brought over from Africa were, largely, unselected bees, that is to say they were as wild as nature had created them".
In the wild, African bees have many natural predators. In order to survive they've developed highly sophisticated defence strategies. In Arizona, Dr Erickson has witnessed, at first hand, the changes in the bee population since the killer bees first arrived.
He continues "The genes for Africanised bees can be found in nearly all bees in Southern Arizona now. I think the feral population here is almost entirely Africanised. It's probably over 95%".
Some of the meanest bees in Arizona are kept at an apiary outside the city of Tucson. Dr Erickson and his team try to provoke the killer bees to find out more about their defensive behaviour. He tells us "If you disturb one of these extremely defensive Africanised colonies half the colony, perhaps 40-60%, will come out at once. You'll have anywhere between 5,000 and 15,000 bees in the air and they'll be out in about 15 seconds".
The venom of the killer bee is no more potent than the venom of the calmer honey bee. It's the huge numbers in which killer bees attack that makes them so lethal. Once disturbed, killer bees can remain angry for twenty-four hours, attacking people and animals within a kilometre of the hive.
Dr Kirk Visscher, Professor of Entomology ponders "The really remarkable thing about the Africanised bees is, aside from their strong defensive behaviour, that following the introduction in the 1950s they've been able to spread at 100Km or more each year".
Killer bees have managed to take over the local bee population wherever they go thanks to their amazing reproductive powers. A swarm is a bee's way of reproducing. When the colony becomes too large to support itself, the bees rear a new queen. The old queen and about half the workers leave the nest to start a new colony. The bees that leave the nest are between homes. They form a swarm and cluster together until they find a suitable location to start again. Honey bees in Britain swarm once a year in the spring. Killer bees will swarm all year round.
This constant swarming means the killer bees can multiply rapidly in the wild. In a year, a thousand colonies can swarm to produce as many as 22,000 new ones.
Recent scientific research has found a genetic basis for the killer bee's aggressive behaviour. It seems they have a mean gene.
Dr Greg Hunt helped isolate several killer bee mean genes specifically linked to killer bee aggression. He reports "There seems to be at least four genes we've identified that are part of the aggressive or defensive behaviour. One of the genes that influences stinging behaviour seems to be genetically dominant".
Dr Guzman Novoa
In Mexico, where some of the most aggressive bees are found, research is going on to find out why these bees are so dangerous. Field research is carried out just south of Mexico City. The area is almost completely populated by killer bees. More than 400 people have died in Mexico as a result of killer bee attacks.
Dr Ernesto Guzman Novoa, research entomologist is the man in charge, working solely with killer bees in an attempt to understand their behaviour. He wants to know exactly how killer bees organise their defences during an attack.
A colony of bees has a lot to protect. Their valuable queen is the centre of the hive, surrounded by thousands of worker bees who take care of her growing young, gather pollen and nectar for food and guard the entrance to the hive. The workers guarding the entrance will repel bees from other colonies attempting to rob the hive of it's honey.
The team are hoping to gain a better understanding of the connection between the defence of the hive and attacks on humans.
They conduct what they call a "Flag Test" where they wave a small leather patch above an aggressive hive for twenty seconds. After exposure they put the patch into a plastic bag to stop more bees stinging it. They then walk away to see how far the bees will pursue. Bees have been known to give chase for up to 800m. Once out of range of the bees they count the number of stings on the leather patch. They count over 100 stings delivered to the small leather patch in 20 seconds. An average person requires about 800 stings for them to be fatal.
A bee stings once and the dies. But as it stings each bee releases a a scent known as an alarm pheromone. This signals other bees from the hive to join in the attack.
However, killer bees have an early warning system to alert their victims to danger. Dr Erickson discovered that in killer bee colonies a handful of bees are on constant patrol covering about a 30m radius around their home. If you enter this zone the bees will collide with you, not sting you, as a warning to leave their territory. If you heed the warning and go they will not attack.
Dr Steve Thoenes who works as a bee remover believes the idea of the killer bee is a result of media sensationalism after a few early Africanised bee incidents. He claims that there are more deaths from traffic accidents and lightning strikes than there will ever be from bee attacks.
Despite his attack, Kent Griffith now works as a bee remover. He is convinced that the Africanised bees are becoming less aggressive as the worst hives are eradicated, removing the most aggressive genes from the larger bee population.