Invasive Insects—How Dangerous Are Killer Bees in the USA?
Killer bees are big news in the US. Their gradual spread outward from California has engendered fear in the general population and concern amongst American honey producers and farmers. So great is the hysteria that Hollywood cashed in with two horror movies, both called Killer Bees, released in 1974 and 2002 respectively.
Now I have a problem with any animal or insect being dubbed a killer. Many are predators that have to kill to eat, and most animals and insects will defend their young and territory if threatened. So how did the so-called killer bees earn their fearsome reputation, and where did they come from?
How Did Killer Bees Get to the US?
They are what is known as an invasive species. These bees are not native to the US. They are a hybrid created in Africa by crossing the native East African lowland honey bee with several species of European honey bees. Because of this, they are also known as Africanized bees.
A scientist called Warwick Kerr was looking for ways to boost honey production, so he shipped some of these Africanized bees to Brazil. Very early on he began to observe these bees displayed more aggressive behaviours than was typical in European honey bees.
The invasion began in 1957 when a beekeeper visited Sao Paulo. While he was working with the bees, he let 26 Tanzanian queen bees and their swarms loose from quarantine by mistake.
To stop the bigger queens and drones escaping from the hives, they had been equipped with ‘queen excluders’. The visiting apiarist thought these were impeding the worker bees from going about their business collecting pollen, so he took them away. The killer bees took their chance, made good their escape and spread throughout the Americas.
Most of the invasive species in the world are in their new environments due to the direct agency of man. They have been purposefully taken along when people migrated, or hitched a ride in their ships, trucks and planes. In the case of some invasive species, such as the cane toad in Australia, they were even deliberately introduced to help solve an environmental problem, before creating one of their own.
The amazing success of the killer bees is, however, all down to them. Once they were released, they disseminated across South America into the US, with no further help from man than that initial accident. They helped their advancement by invading local European honey bee hives, killing their queen and introducing a killer bee queen to replace her.
The invasive swarms arrived in Mexico in 1985, and in the same year, the first Africanized bee colony in the USA was detected on a San Joaquin Valley oil field. How did they get there? The most likely explanation is they hitched a ride with a load of oil-drilling pipes imported from South America.
A swarm was also recorded crossing the Rio Grande River from Mexico into Hidalgo, Texas in 1990. This small community has commemorated the event by constructing a large, styrofoam killer bee statue and naming its football team the 'Rio Grande River Valley Killer Bees'. Colonies have subsequently been found in many of the other southern states, including Nevada, New Mexico, Florida, Utah, Oklahoma, Arizona, Louisiana and Texas.
Are They More Dangerous Than Other Bees?
It was early on in this invasion they acquired their damning label of killer bees. What earned them this title? Are they more dangerous than European honey bees?
In 2013, a Texas farm was engulfed by a swarm of over 40,000 killer bees, killing two horses and five hens. A human could easily have lost their life. These attacks are, luckily, still isolated events, but there are fears they could become more common as the killer bee population grows larger.
The Africanized bees are a more aggressive, defensive species. They are more irritable and react quickly to being disturbed, sending out greater numbers of defenders to chase off an intruder for up to a quarter of a mile.
If disturbed, a European honey bee hive will send out 10-20 workers to assess the threat. Africanized bees will send out hundreds. They will also remain aggressive for a couple of hours—a lot longer than the 20 minutes it takes European honey bees to simmer back down.
They are militant in defence of their queen and colony. If they catch up with their perceived attacker, be it human or animal, they will sting them many, many times. They want to chase the threat away with the pain of the stings. The venom from the sting also sends a message to the other killer bees in the colony that this person or animal is a risk to the hive, which drives them to sting numerous times.
Bee sting allergy is the most common cause of human fatalities from being stung. A healthy adult can tolerate around ten stings per pound of body weight, and so can survive over one thousand stings.
Children are more vulnerable, as they are not as heavy. The danger with the killer bees is this tendency to sting multiple times if threatened, which has led to the deaths of over a hundred people since they arrived in the US.
It also tends to be easier to disturb an Africanized bees’ nest. They are less fussy where they build their colonies and they tend to be smaller, making it much likelier they can be stumbled into by accident, upsetting the occupants.
Unlike the man-made hives occupied by the European honey bees, they build their colonies under the eaves of houses, in trees and bushes and contained spaces like unused drainpipes.
Venom of Africanized vs. European Bees
It may surprise you, but the venom of the Africanized bee is not as toxic as that of a European honey bee and they are smaller in size. If you were comparing the two species on an individual level, the European honey bee potentially poses the larger threat.
However, they are more docile, and it is thought this could be partially down to us. In western Europe and the US, they have been bred for centuries by skilled apiarists, who have worked hard to produce placid colonies who are easy to manage.
In other parts of the world, such as Africa, ‘honey hunting’ is more typical. The bees are not tended and hives in the wild are torn apart and the honey taken. This may have encouraged the bees to react faster and in a more aggressive way.
Impacts on Agriculture
Are killer bees a threat to agriculture? Honey producers are concerned because they out-compete the European honey bees, but produce less honey. They are also more difficult to handle because of their aggressive behaviour.
Farmers rely on honey bees to pollinate their crops of vegetables, fruits and seeds. To facilitate this, especially in California, pollination services have been set up that move the hives from area to area, according to the season. The hives are transported by road on trucks and delivered where they are needed. There are fears that when the honey bee population is taken over by the Africanized bees, the hives will be more difficult, if not dangerous, to transport.
Also, because of fears for public safety, regulations may be put in place to stop hives being moved from areas that have been colonised by the Africanized bees.
However, recent years have seen an alarming decline in the managed honey bee populations, mainly due to colony collapse disorder. Most of the Africanized bee colonies are still feral and they seem to be thriving and extending their range. They are also infiltrating the managed population, so many beekeepers see they now have a mix of the two species in their hives.
It is not known why the killer bees are not so affected by colony collapse disorder. It may be they have some type of resistance to the mites thought to cause the condition. But as agriculture is reliant on having enough pollinators to produce crops, they may in the end prove to be saviours rather than destroyers, the benefits outweighing the dangers of managing and transporting them.
Are you worried about the spread of Killer Bees?
Invasive insects around the world cost the global economy billions of dollars every year. They decimate crops, destroy infrastructure and spread disease. There are invasive insects who can disrupt whole ecosystems when they move in, making indigenous species vulnerable. So, despite their formidable reputation, are the so-called killer bees so bad? With proper management, danger to humans and animals can be minimised as much as possible.
Education is key, and in areas where the Africanized bees are present, the more information on their behaviour and possible risks people have, the more they can help to protect themselves. With pollinators in decline, any species that can grow its numbers and help with pollinating our precious crops, fruits and flowers is to be applauded rather than feared.
- Killer Bee on Lavender - Wikimedia Commons - Jose Manuel Podlech - Creative Commons Attribution-Share Alike 2.0 Generic
- Killer Bee Statue - Wikimedia Commons - Public Domain
- Swarm of Africanized Bees - Wikimedia Commons - Jonathan Wilkins - Creative Commons Attribution-Share Alike 3.0 Unported
- Texas farm swarm: https://www.theguardian.com/environment/2013/aug/06/bees-crisis-buzzfeeds-analysis
- Bee stings: https://www.buzzaboutbees.net/bee-sting-facts.html
- Pollination: http://calag.ucanr.edu/Archive/?article=ca.v046n01p18
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