The Csd gene, of which there may be more than 100 variants, plays a key role in determining the sex of bees. These genes are brought together during sexual reproduction: Where the genome subsequently contains two different variants of the Csd gene, a female bee develops, which is then raised (left). Where fertilisation brings together two variants that are the same, a male bee would develop, but it is not raised by the worker bees. Male bees – the drones – are instead generated via asexual reproduction. (HHU/Paul Schwaderer/stock.adobe.com – Alekss, Tran-Photography, NewsX/Bee)
