# The Neuropeptide Neuroparsin-A Regulates the Establishment of Dominance Hierarchy in Bumblebees

## TL;DR

This paper shows how a neuropeptide called Neuroparsin-A helps bumblebees form dominance hierarchies through brain gene activity changes.

## Contribution

The study identifies Neuroparsin-A and its receptor as a conserved signaling axis involved in dominance hierarchy formation in bumblebees.

## Key findings

- Kenyon cells show significant transcriptional divergence linked to synaptic and signaling pathways.
- Neuroparsin-A is upregulated in dominant bumblebees' Kenyon and glial cells.
- Ecdysone-responsive transcription factors are key regulators of brain plasticity and behavior.

## Abstract

The regulation of reproductive division of labor in eusocial insects is pivotal for the evolution and maintenance of social organization. In Bombus terrestris, dominance hierarchies emerge among orphan workers through repeated agonistic interactions, forming distinct behavioral ranks. To explore the neural basis of this process, we combined behavioral assays with single-nucleus RNA sequencing to profile brain-wide gene expression across α-, β-, and γ-bumblebee workers. Our analyses revealed pronounced transcriptional divergence among Kenyon cells, which exhibited enrichment in synaptic, insulin, and MAPK signaling pathways. Among the neuropeptides examined, Neuroparsin-A was markedly upregulated in the Kenyon cells and glial cells of dominant workers, while its receptor, OR1, showed strong expression within Kenyon populations, suggesting a conserved neuropeptide–receptor axis in social Hymenoptera. Gene regulatory network inference further identified ecdysone-responsive transcription factors, including br, Eip74EF, Hr38, Hr3 and Hr4, as key regulators linked to neural plasticity and behavioral differentiation. Together, our findings uncover a neuroendocrine mechanism in which Neuroparsin-A signaling coordinates brain transcriptional programs associated with dominance hierarchy formation in queenless bumblebee societies, offering new insights into the molecular underpinnings of eusocial behavior.