Instead, they may be genetically wired to beg for food.
Male bees -“drones” – actually cannot digest pollen, the most important source of protein for bees. To avoid starvation, they depend on worker bees feeding them a pre-processed paste that workers make from pollen. It’s not a communist love-fest, though, drones instead must convince workers to provide the food.
Over time, they evolved to be able to beg.
The drone in the center begs worker bees for food. Photo: HHU/Steffen Köhler
A recent study searched for regulators that wire the male honeybee’s brain during development in such a way that the animals display their innate social behavior for this food exchange. Using CRISPR-Cas9, they introduced a green fluorescent protein encoding gene into the Fru gene. This enabled them to label the cells in which the transcription factor is active. They detected it in neurons in the nervous system, which process sensory information and are used for decision-making.
They found that the behavioral interactions necessary for food transfer can be traced back to a transcription factor – a protein that can switch many other genes in the genome on and off
– called the “fruitless” or “Fru” protein, and that this factor is only active in male bees. Fru influences a neural network of around 1,800 neurons that is closely related to cooperative behavior.
The team then created so-called knockout mutants in which they switched off the Fru transcription factor, then attached QR codes to the bodies of the mutant drones and observed their behavior using an automated camera system.
The decision-making behaviour of the bees was disrupted. They were unable to approach their conspecifics properly, begged for food less frequently and interacted in such a way that they received less food, but other behaviors of the drones were not affected.
The mutants were also not distinct in their odor profile, as co-author Dr Thomas Eltz from Ruhr University Bochum noted. Individual odors are determined by the body’s own hydrocarbons, which are important for animal interaction. The olfactory center, where odors are processed, was also unaffected.
They say these cooperative behaviors are specified by a genetic program was newly formed in the course of evolution. It defines the neural controls, which determine whether and for how long the behavior sequence is executed based on perceived sensory information. Such mechanisms enable the necessary behavioral adaptations to social partners.
Citation: Köhnen, S., Ulbricht, P., Sturm, A. et al. The fru gene specifies male cooperative behaviors in honeybee colonies. Nat Commun 16, 11203 (2025). https://rdcu.be/eWyik