Male honeybees inject queens with toxins to blind them during sex

10 Sep 2019

Queen honeybee in a hive (centre) with a small radio tag on her back. Image: Barbara Baer-Imhoff /UCR

‘Eye-opening’ research has found that male honeybees go to extreme lengths to prevent the queen leaving during sexual activity.

In their brief time on Earth, male honeybees go to extreme lengths to make sure their genes are carried on.

New research published to eLife has found that during sex, the male will inject toxins into the queen to temporarily blind her. Once all activity has finished, the male dies and the queen’s sight returns – she can live many more years without ever mating again.

According to Boris Baer of the University of California, Riverside, the males have developed these toxins to maximise their one chance of fathering offspring.

“The male bees want to ensure their genes are among those that get passed on by discouraging the queen from mating with additional males,” said Baer, who is senior author of the study. “She can’t fly if she can’t see properly.”

The toxins were identified by the researchers as proteins contained in male bees’ seminal fluid used to maintain sperm. Previous research showed these seminal fluid toxins are also used to kill off their male rivals.

Preventing the die-off

Baer’s first interest in the powers of this seminal fluid came as a doctoral student, when he noticed that if the queens were injected with the toxin and no sperm during insemination, they would stop mating and become highly aggressive to males. After determining what the most likely protein behind this blindness was, the researchers inseminated queens with a flickering light and measured the response to it via tiny electrodes in her brain.

The vision and corresponding flight-impairing effects were found to kick in within hours, but Baer said it is likely reversible given that queens tend to fly successfully to establish new colonies. Tiny tags were installed on the queen bees’ backs that could be read by scanners at the hive entrances, showing the queens had difficulty finding their way back to their colonies.

Baer said having a better molecular understanding of honeybee mating habits could help improve breeding programmes in the future.

“More than a third of what we eat depends on bee pollination, and we’ve taken bees’ services for granted for a very long time,” Baer said. “However, bees have experienced massive die-offs in the last two decades. Anything we can do to help improve their numbers will benefit humans, too.”

Colm Gorey was a senior journalist with Silicon Republic