Africanized bees, commonly known as “ killer bees “, are much more aggressive than their European counterparts. Now, a team of researchers have examined the changes in neuropeptides that take place in the brains of these bees during their aggressive behavior and have shown that they can turn normal bees into ‘killers’ by injecting them with certain peptides.
Just a few neuropeptides make the difference between a honey bee and one that has an irritable urge to wipe out everything that moves.
To discover what makes Africanized “killer bees” so hostile, scientists from the State University of São Paulo (Brazil) compared their neurochemistry with that of their more docile relatives and found that it is mostly due to a surprisingly simple chemical change.
The reputation of the killer bees is well deserved. Their venom is no more deadly than average honey bees and they are even slightly smaller, but they are incredibly aggressive, and it doesn’t take much provocation to goad a swarm of these bees into a raging, stabbing pain machine.
The more hostile an animal is, the more caution must be exercised
These grumpy striped insects appeared in the late 1950s, after Brazilian beekeepers imported an African variety of Apis mellifera scutellata in order to increase honey production. It seems that the bees did not understand the fine print very well and the honey bees ended up paying for it.
Since then, these aggressive hybrids have spread to northern California and remain a legitimate threat. Several hundred people have lost their lives due to its relentless sting. And it is that this subspecies is also extremely sensitive to the presence of human beings. They tend to attack the eyes and face, and the only thing you can do about them is run away.
But what happens in their brain to make them act this way?
To get to the bottom of the mystery, the researchers in this latest study had to collect a sample of killer bees (something not without danger). Using a rather curious trick, they managed to catch them to observe their tiny brains.
Comparison of the full range of brain proteins from two bee samples using mass spectral imaging revealed a clear, but simple difference.
One of the suspect proteins was called Apis mellifera Allatostatins A , a neuroprotein already known to play a key role in bees’ learning and memory, as well as their overall development.
The other group of proteins, described as tachykinin-related peptides , appear to influence sensory processing.
In the aggressive hybrids, these two groups of neuropeptides had been cut into shorter proteins, and they were found in different groups of brain tissue called neuropil.
To verify that these proteins were significant in transforming bee behavior, the scientists injected truncated forms of these neuropeptides into the brain of a group of non-aggressive bees.
As expected, the bees did not seem very happy when they woke up, because by modifying their brain chemistry they had also transformed into killer bees.
However, it is still unknown why the size and distribution of these neuropeptides lead to such aggressive behavior. Learning more about the cascade of effects that these proteins have on a bee’s nervous system could tell us more about the development of the nervous systems of bees, as well as those of insects in general.
Reference: MALDI Imaging Analysis of Neuropeptides in Africanized Honeybee (Apis mellifera) Brain: Effect of Aggressiveness. Institute of Biosciences, Department of Biology, Center of the Study of Social Insects, University of São Paulo State (UNESP), Rio Claro, São Paulo 13506-900, Brazil. J. Proteome Res., Article ASAP DOI: 10.1021 / acs.jproteome.8b00098 2018
