A Bee With Two Fathers and No Mother Has Been Discovered

Scientists have found a female bee that had two fathers and no mother in the first documented case of its kind.

Honeybees are known as haplodiploid. This is a system of sex determination—females come from fertilized eggs, while males are the result of unfertilized eggs. But in one to two percent of cases, another system emerges—"sex mosaics." These bees are known as gynandromorphs and they develop from several cell lines of different origin and different sex.

Sarah Aamidor, from the University of Sydney, Australia, and colleagues, were investigating gynandromorph bees to better understand the flexibility of honeybee reproduction. While scientists know gynandromorphs emerge as a result of a genetic mutation, how and why it happens is not clear.

In mammals, when sperm enters an egg and fertilizes it, a chemical reaction happens to prevent other sperm from entering. However, in honeybees, more than one sperm can enter—a phenomenon known as polyspermy. This is normally what happens with gynandromorphs—more than one sperm enters the egg and fuses to the initial cell cluster. "[They then] begin to divide and thus become part of the developing embryo," Aamidor told Newsweek.

In their study, published in the Royal Society Biology Letters, Aamidor and the team carried out a genetic investigation into 11 gynandromorph honeybees from a single colony. For each bee they dissected, imaged and collected tissues from different parts of the body. They extracted DNA from each tissue sample and analyzed them individually.

Most of the bees were found to have three or four parental origins—with two or three fathers to one mother. But their results also showed that one bee had been produced from two fathers and no mother. It lacked any maternal genetic material, so the scientists propose it was created by a fusion of two sperm.

"This is the first report of a phenomena of a bee with two fathers and no mother in hymenoptera," Aamidor said. "In mammals, an embryo can't develop from two fathers (or mothers) so it was indeed surprising. This phenomena is possible due to honeybees being polyspermy and, as this work shows, extremely flexible in the way they fuse their genomes, which may be due to them being haplodiploid."

The discovery of a female made from two sperm and live bees with four different parents provides a new insight into how flexible honeybee reproduction is. Concluding, the team say this flexibility might also be found in other haplodiploid insects like ants and wasps. "Beyond these already known examples, there are likely to be equally extraordinary social systems that have not yet been identified or even imagined," they wrote.

Elizabeth Duncan, a lecturer in zoology at the U.K.'s Univeristy of Leeds, who was not involved in the research, said the findings show how little we know about insect reproduction. "This is the first time that scientists have observed two sperm fusing to produce a female offspring in bees, ants or wasps," she told Newsweek. "In other animals, like some ant species, a single sperm can enter an egg with no nucleus and go on to form male offspring. This phenomenon, called androgenesis, is thought to be incredibly rare and has been linked with the ability of some ant species to invade new environments.

"This study highlights that we still have a lot more to learn, not just about honeybees but also about how these alternative ways of reproducing come about and the impact that they might have on the ability of species to move into new environments and the survival of species."

This article has been updated to include quotes from Elizabeth Duncan.