Flying Blind

An artificially inseminated queen with a radio-frequency identification tag (center, blue dot) is attended to by her royal court.

Barbara Baer-Imhoof

For a brief period early in her life, the new queen of a honeybee colony will leave the hive on multiple mating flights to collect the sperm she needs for a lifetime of reproduction. She will pair with many males to ensure the colony is genetically diverse, and thus more resistant to parasites and disease. This is problematic for the males, as more mates decrease the chance that any one will pass along his genes. A new study confirms that males have developed a strategy to reduce their competition: their seminal fluid temporarily impairs the vision of the queen bee, making it harder for her to take subsequent mating flights.

Ecologist Boris Baer of the University of California Riverside and an international team of scientists from Denmark, Australia, and the United States investigated the effect of male honeybees’ seminal fluid on queens’ mating flight behavior, gene expression, and retinal function. The queens were fitted with electronic tracking devices, which showed that artificially inseminated queens were more likely to get lost and show signs of disorientation. RNA-sequencing revealed that proteins in the seminal fluid triggered changes in genes related to visual processing. And electroretinography, which measures electrical signals of the retina, showed reduced responses to flickering light twenty-four to forty-eight hours after insemination.

The team also noted that inseminated females attempted their mating flights sooner than queens injected with a saline control—possibly to fly before impending vision loss fully sets in. This provides further evidence of a sexual arms race between male and queen honeybees, and may prove valuable at a time when U.S. beekeepers have lost over 40 percent of their colonies from 2018 to 2019, the highest winter losses ever recorded. Honeybee breeding programs could potentially be improved by, for example, letting the queens out for only one or two mating flights, says Baer. “But when they go out, we ensure that there is every possible genetic variation in terms of other beehives around.” (eLife)