Found Half-Male, Half-Female Bee!

In general, animals tend to be sexually dimorphic. There are males, with small gametes, and females, with large gametes, both of which are necessary for sexual reproduction. From time to time, however, nature plays tricks! As in the case of this specimen of Megalopta amoenae, a species of nocturnal bee native to Central and South America. On its left side, in fact, the bee is physiologically male. It has a small, delicate jaw, a long antenna and a thin, delicate hind leg with fewer bristles. The right side, on the other hand, has female characteristics. It has a shorter antenna, a pronounced, toothed jaw and a thick, hairy hind leg.

ginandromorphism is a phenomenon already known in nature, it has been found in at least 140 species of bees, as well as butterflies, birds and crustaceans (but virtually unknown in mammals). The peculiarity of this finding is that the specimen in question was discovered alive! Until now, in fact, this phenomenon had only been detected after the insect was already dead and in a research centre. Researchers led by entomologist Erin Krichilsky of Cornell University were in fact conducting a study on circadian rhythms in M. amoenae, working with live bees from the Barro Colorado Island forest in Panama at the Smithsonian Tropical Research Institute. This was a stroke of luck, because studying the still-living ginandromorphic bees could help us discover a lot about these fascinating insects.

"This phenomenon may offer insight into the evolution of specialised morphological traits, such as the male morphology of parasitic bee broods, the modified morphology of social insect castes and new methods of reproduction," the researchers wrote in their paper. Sex determination in Hymenoptera (the order of insects that includes bees, ants and wasps) is very special. If an egg is fertilised, it produces a female, while an unfertilised egg produces a male. But, as a 2018 research discovered, if sperm from a second and even a third individual enters an already fertilised egg (a female embryo) it can divide to produce male tissue, resulting in a gynandromorph.

A number of studies have focused on different areas of behaviour in live gynandromorph bees, such as nesting and courtship. As this team was already studying circadian rhythms (which synchronise a species' behaviour and interactions with the external environment) they decided to see if and how these rhythms differed in the gynandromorph individual found alive. They followed and studied the bee for four days and found that it tends to wake up a little earlier than both male and female bees. However, its periods of higher intensity activity more closely resembled female behaviour. This could indicate that the brains of gynandromorphic bees have mixed sex-specific signalling and are unable to integrate the two. Or it could be that the bee is just a bit individual, gynandromorphism aside.

This result is not much, but it provides an initial starting point and reference from which to build if other living gynandromorphic bees can be found and can be studied. As the researchers write in their paper, it must be considered that the study was only carried out on a single sample. "Further studies are needed to better understand whether there is a difference in the sex-based circadian rhythm in this species and to distinguish what the deviant activity pattern of the gynandromorph results from." The research was published in the Journal of Hymenoptera Research. Source: Science Alert.