It is an incredible discovery . A team of scientists led by Cornell University (USA) has identified a bee that is male on its left side and female on its right side. It is a rare condition known as gynandromorphy and occurs in various groups of insects, such as Coleoptera, Hymenoptera and Diptera , among others, and also in certain crustaceans and arachnids (although practically unknown in mammals); but this is the first known example of gynandromorphism in the bee species Megalopta amoen a, and the second case in the genus Megalopta , or sweat bees, in more than 20 years.
The first dynendromophic individual of its species
The bee in question ( Megalopta amoena ) is four millimeters long and is a nocturnal insect native to Central and South America. Specifically, the researchers found the bee inside a nest in Panama, in a forest on the island of Barro Colorado. When the nest was collected, the bee was a larva enclosed in a brood cell, a chamber in the honeycomb where young bees grow, and scientists discovered its peculiarity when it emerged as an adult.
On its left side , it is physiologically a male: it has a small and delicate jaw, a long antenna and a rear leg with few hairs.
On its right side, it is a female: it has a shorter antenna, a well-pronounced serrated jaw and a thick, hairy hind leg.
This bee is so special also because, generally, the rare genetic condition of bilateral gynandromorphism is only seen when the insect is already dead and is on display in a museum.
“Finding M. amoena was like finding gold or winning the Darwinian lottery,” said Erin Krichilsky, a Cornell University student and lead author of the study published in the Journal of Hymenoptera Research.
Although this bee has bilateral gynendromorphy, since its sex differences are divided in half, the gynendromorphy can also be axial, in which the front of the body is of one sex and the back of another. It can also appear even as a mosaic, with male and female features mixed and scattered throughout the animal’s body.
Sex determination in the order of insects, which includes bees, ants, and wasps, is truly peculiar. If the eggs are fertilized, worker bees (female bees) will hatch. The unfertilized ones will be drones (male bees). But there can be double fertilization : If the sperm of a second and even a third individual enters an egg that is already fertilized, a female embryo, it can divide to produce male tissue, resulting in a gynandromorph specimen.
How it behaves?
The researchers followed her for four days and found that she tends to wake up slightly earlier than male and female bees. However, their peak periods of activity were more like female behavior.
“More studies are needed to better understand whether there is a difference in the circadian rhythm based on sex in this species, and to distinguish from what the deviant activity pattern of the gynandromorph derives,” the authors explain.
Referencia: Erin Krichilsky et al, The first gynandromorph of the Neotropical bee Megalopta amoena (Spinola, 1853) (Halictidae) with notes on its circadian rhythm, Journal of Hymenoptera Research (2020). DOI: 10.3897/jhr.75.47828
