Bees are unimaginably territorial (有地盘意识的), fighting to death to defend their home with painful stings (螫刺). But killer bees are particularly fierce. They appeared after African bees were imported to Brazil in the 1950s. By the 1980s, they had spread north to the United States, outgunning native bees along the way. Their massive attacks have killed more than 1,000 people.

Mario Palma, a biochemist at Sao Paulo State University in Rio Claro, Brazil, who studies social behavior in bees, wanted to understand the basis of this aggression. So he and his colleagues swung a black leather ball in front of some killer bees and collected the bees whose stingers got stuck in the ball during the attack. They also collected killer bees that remained in the cell. The analysis suggested that killer bee brains have two proteins that—in the aggressive bees—quickly break into pieces to form a so-called “neuropeptide (神经肽)”, they reported this week in the Journal of Proteome Research.

Palma and his colleagues already knew that bee brains have these two proteins. “We were astonished when we identified some very simple neuropeptides, which were produced in a few seconds,” Palma said. Killer bees that remained in the cell did not make these neuropeptides, he reported. And when his team put these neuropeptides into young, less aggressive bees, they “became aggressive like older individuals”.

Palma added that these neuropeptides also increase the production of   energy   and alarm chemicals. They could also encourage the nerve cells in killer bees needed to make the stinging attack. “There is a fine biochemical regulation in the killer bee brain,” he said. Researchers have found these neuropeptides in other insects, but few had associated them with “fight” behavior.

【小题1】What is special about bees?

A．They are particularly fierce.	B．They show territorial behavior.
C．They were imported to Brazil.	D．They live in harmony with other insects.

【小题2】Why did Palma and his colleagues perform the experiment?

A．To understand bees’ social behavior.

B．To study why killer bees are aggressive.

C．To prove bees love flying around.

D．To learn how bees communicate with each other.

【小题3】What finding surprised the researchers during the experiment?

A．There are two proteins in killer bee brains.

B．Young killer bees are fiercer than older ones.

C．The killer bees make an attack immediately.

D．Killer bee brains produce neuropeptide quickly.

【小题4】What will the author probably talk about following the last paragraph?

A．The form of these neuropeptides in killer bees.

B．The function of these neuropeptides in other insects.

C．The application of these scientific methods in other insects.

D．The production of energy and alarm chemicals in killer bees.