Why is the Africanized killer bee so aggressive?

The species is notorious for its aggression. And now we know where this adrift behavior comes from.

The Africanized honey bee is often referred to as ‘killer bee’. The critters have a rather negative reputation because they can be very aggressive. These angry swarms have already killed several people. But why is the killer bee so aggressive? researchers figured it out.

The Africanized honey bee is actually the result of a genetic experiment that went wrong. Brazilian researchers imported South African subspecies and bred them with European-derived honey bees in the 1950s. The idea was to develop a better subtropical variant. But then some of them accidentally escaped. And these escaped bee horses then unexpectedly with the local bees.

It resulted in a new species that no one was really waiting for. “The resulting bees had an invasive character and were very aggressive,” explains researcher Amro Zayed. “Much worse than the European honeybees used by North and South American beekeepers at the time.” Where this aggressiveness came from was a great mystery. “The genetics that caused this hyper aggression was not well known,” Zayed continues. “But the prevailing theory was that the Africanized honey bee was aggressive because the South African bees were.”

The new colonies quickly expanded. For example, the Africanized honey bee spread not only across Brazil, but also across South America, Central America, and, in 1990, across the southern states of the United States. Today, they have completely replaced the European-derived honey bee in Brazil. In addition, they have become the most common honey bee from northern Argentina to the southern United States. This success has to do with several factors. First of all, they come from a tropical area. It means that in these climates they thrive better than their European counterparts. In tropical areas where both species live side by side, the Africanized honey bee can easily compete with European honeybees. In addition, Africanized honeybees roam more and will, therefore, be able to spread more quickly over a large area.

The genetically engineered bee now occurs in many places, where it sometimes ends up in the waters of unsuspecting people. In the United States, Africanized honeybees are responsible for one to two deaths a year. To determine where the hyper aggression of the Africanized honeybee comes from, the researchers decided to conduct an experiment. They collected 116 Brazilian Africanized honeybee colonies and waved a black leather ball a few minutes before the beehive entrance to provoke a reaction.

Many bees flew aggressively at the ball and immediately crossed. “Some colonies lit the ball 90 times or more per minute,” said researcher Samir Kadri. “We decided to sequence the genomes of the most aggressive colonies. Next, we compared the genomes of the most and least aggressive colonies to discover mutations related to their different behaviors.”

The researchers found that the most defensive colonies were more akin to South African honeybees. But after sequencing the genomes, the team discovered that the most aggressive specimens were related to Western European bees. It means that the aggressiveness in the Africanized honey bee has been brought about by a European ancestor. Although it is mainly the lousy mix that counts. “The mixing of the two honeybee subspecies ultimately led to the hyper aggression we see in this invasive species,” Zayed said.

Although the study’s findings answer a pressing question, the researchers have not yet released the subject. Follow-up research should show exactly how the DNA of these two subspecies influences the aggressive immune response.

Reference and citations: ” York study: European ancestry plays role in ‘killer’ honey bees’ aggressiveness “ – York University (via EurekAlert)