# Olfactory Susceptive Difference in Gregarious and Solitary Locusts

## TL;DR

The study explores how the sense of smell in locusts changes when they switch between living alone and forming swarms, revealing new insights into their behavior and potential control methods.

## Contribution

The research provides a detailed multi-level analysis of olfactory system plasticity in locusts during phase transitions.

## Key findings

- Solitary male locusts have the highest number of antennal sensilla, with basiconica sensilla being most abundant.
- Solitary males show the greatest electroantennogram (EAG) sensitivity to phase- and sex-specific volatile compounds.
- Solitary males exhibit significant upregulation of Or genes across all sex-phase combinations.

## Abstract

The migratory locust, Locusta migratoria, is a devastating agricultural pest that forms destructive swarms. Its olfactory system exhibits plasticity in response to population density, playing a key role in aggregation and large-scale crop damage. In this study, we performed a comprehensive, multi-level comparison of the peripheral olfactory system between solitary and gregarious locusts, exploring the specific mechanisms underlying changes in the peripheral olfactory system of locusts during density-dependent phase transitions. Our findings provide insights into the biological basis of locust swarm formation and the adaptive strategies of locust peripheral olfactory systems to changing environments.

The migratory locust, Locusta migratoria, possesses a highly specialized olfactory system that exhibits remarkable density-dependent plasticity, which plays a crucial role in the formation of large aggregations and the resulting severe crop damage. However, the mechanisms by which population density influences phase-related plasticity in olfactory perception remain largely unexplored. Here, we conducted a comprehensive, multi-level comparison of the peripheral olfactory system between solitary and gregarious locusts. We found that solitary male locusts display the highest total number of antennal sensilla, with basiconica sensilla being the most abundant and particularly prominent in this group. At the physiological level, solitary males also displayed the greatest overall sensitivity in their electroantennogram (EAG) responses to volatile compounds highly specific to both phase and sex. At the molecular level, solitary males exhibited a significant upregulation of Or genes across all sex-phase combinations. These findings illuminate the intricate adaptation strategies of the insect peripheral olfactory system in response to environmental changes.