Researchers from New York University and the University of Florida have identified the Orco protein as essential for the survival and function of olfactory neurons in ants. The study, published in Science Advances, focused on Harpegnathos saltator ants and found that mutating the orco gene significantly reduced olfactory neurons, impairing the ants’ ability to interact socially. Ants rely heavily on their sense of smell, with 400 smell receptors aiding in pheromone communication.

The loss of these olfactory neurons had a profound impact on the ants’ social behaviors. We found that the antennae—the ant’s equivalent of a nose—had very few cells, suggesting a lack of olfactory neurons in the mutant ants,” said Hua Yan, assistant professor of biology at the University of Florida and the study’s senior author. The researchers used advanced techniques, such as single nucleus gene expression profiling and fluorescence microscopy, to analyze olfactory cell development.

They discovered that without Orco, most olfactory neurons die before reaching adulthood. This neuronal death is likely due to stress caused by the inability of odorant receptors to form a complex with Orco, leading to cellular malfunction and death.

Orco protein shapes ant interactions.

Some neurons must periodically ‘fire’ to develop properly. Without Orco, smell cells did not ‘fire’ and complete their development, leading to their death,” explained Bogdan Sieriebriennikov, a postdoctoral fellow at NYU’s Department of Biology and the study’s first author. Interestingly, some odorant receptors survived even without Orco, suggesting that these cells might have other roles.

The study also found odorant receptors in non-smell cells, such as motion-detecting neurons and glia, which support neuron function. This might be due to imperfect gene regulation or could indicate new functions for these receptors. The findings provide a comprehensive overview of olfactory neural development in ants and reveal potential unique processes in social insects that may not be present in solitary insects.

Our findings enhance our understanding of social insects’ sensory systems, including olfactory neural development that establishes a framework for social communication,” Yan concluded. The study was supported by grants from the National Institutes of Health, the National Science Foundation, and the Human Frontier Science Program.