Male and female? Heidi & Hans-Juergen Koch/ Minden/Getty

We’ve still got plenty to learn about “the birds and the bees”. A close looker has revealed that some honeybees born partly male and partly female have up to four parents – and some of them have no mother at all.

In bees, unfertilised eggs develop into males, or drones, who seek out queens to mate with. Fertilised eggs usually develop into female workers.

However, queens mate with at least 10 males to produce new colony members, and more than one sperm enters each egg. In a few rare instances, individual bees can end up with some tissue derived from the fertilised egg, which is female, and some from extra sperm, which is male.


An organism that has male and female reproductive organs is called a hermaphrodite – but organisms, like the bees, with both male and female tissue throughout the body are known as gynandromorphs.

Sarah Aamidor and colleagues at the University of Sydney, Australia, studied 11 gynandromorph honeybees from a single colony to learn more about how these individuals develop.

Five of them had normal worker ovaries, but three others had “queen-like” ovaries, containing larger numbers of tubes called ovarioles. One had normal male reproductive organs, and two had partial male organs.

Genetic tests revealed the gynandromorphs’ unusual family histories. Nine of them had two or three fathers and one mother. One had no mother and two fathers, resulting from the fusion of two sperm.

There is no evolutionary advantage to producing gynandromoyphs. “We assume they are genetic mistakes,” says Aamidor. She thinks this colony had a high number of gynandromorphs because of a genetic mutation in the queen, but exactly which genetic mutations make gynandromorphs more likely to appear are unknown.

Gynandromorphs occur rarely in other insect species, crustaceans and even birds. They sometimes give scientists valuable insights into how certain behaviours are related to parts of the body.

Journal reference: Biology Letters, DOI: 10.1098/rsbl.2018.0670