New research from the University of California (UC) at Riverside finds male honey bees inject toxins during sex that cause temporary blindness in queens.
All sexual activity occurs during a brief early period in a honey bee’s life, during which males die and queens can live for many years without ever mating again.
UC Riverside’s Dr. Boris Baer, a professor of entomology, says males develop vision-impairing toxins to maximize the one fleeting opportunity they may ever get to father 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,” says Dr. Baer, senior author of the study published in the journal eLife. “She can’t fly if she can’t see properly.”
The toxins identified by the team are proteins contained in male bees’ seminal fluid, a substance that helps maintain sperm.
To test whether the protein had this effect, Dr. Baer’s team presented inseminated queens with a flickering light and measured her response to it via tiny electrodes in her brain. The vision and corresponding flight-impairing effects kick in within hours, but Dr. Baer notes that it is likely reversible in the long term because queens do tend to fly successfully later in life when they establish new colonies.
Studying the seminal fluid proteins required an interdisciplinary team of entomologists, biologists, biochemists and more to identify them and examine their effects on the queens.
This team included Dr. Baer’s wife and co-author, Dr. Barbara Baer-Imhoof, a UC Riverside pollination specialist. As part of this project, Dr. Baer-Imhoof conducted experiments in which she installed tiny tags on queen bees’ backs read by scanners at the hive entrances.
“The tags were similar to those at the self-checkout counter in grocery stores,” Dr. Baer-Imhoof says.
The experiment showed queens had difficulties finding their way back to their colonies if they had been inseminated.
A molecular understanding of honey bee mating habits could eventually be used to improve breeding programs and help insects that pollinate many of the foods we eat.
“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,” Dr. Baer says. “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.”
Learn more about Dr. Baer’s and his team’s research on honey bee seminal fluid here.
Jules Bernstein is an award-winning science writer who has covered topics as varied as gene editing, biofuels and astrophysics. She currently serves as senior public information officer for the University of California at Riverside.