# Functional Characterization of OasiCSP12: A Chemosensory Protein Regulating Olfaction and Phase Change in Oedaleus decorus asiaticus

## TL;DR

This study identifies a chemosensory protein, OasiCSP12, in a grassland pest locust that may regulate its behavior and phase changes through chemical signals.

## Contribution

The study functionally characterizes OasiCSP12 as a chemosensory protein involved in locust phase regulation and olfaction.

## Key findings

- OasiCSP12 is expressed in a phase- and sex-specific manner, predominantly in the antennae of gregarious adults.
- The protein binds to 15 locust body-surface volatiles, including aldehydes like heptanal.
- Structural analysis reveals a hydrophobic cavity where Val86 and Leu71 stabilize ligands via van der Waals interactions.

## Abstract

Oedaleus decorus asiaticus is a major grassland pest whose outbreaks are driven by density-dependent phase change, a process mediated through chemical communication. This study suggests that a chemosensory protein, OasiCSP12, may participate in this process. OasiCSP12 shows phase- and sex-specific expression, with predominant levels in the antennae of gregarious adults. The protein binds specifically to 15 locust body-surface volatiles, particularly aldehydes such as heptanal. Structural analysis identified a hydrophobic binding cavity where residues Val86 and Leu71 are predicted to stabilize ligands via van der Waals interactions. These findings suggest that OasiCSP12 is a potential molecular component in both chemical perception and phase regulation, offering a possible target for the development of behavior-based, eco-friendly control strategies against locust plagues.

The Asian migratory locust (Oedaleus decorus asiaticus) is a major grassland pest in northern China, with outbreak dynamics closely linked to phase transition mediated by chemical communication. This study focused on a chemosensory protein, OasiCSP12, to explore its potential role in this process. We analyzed its expression patterns via qRT-PCR, purified the recombinant protein, and identified potential ligands through fluorescence competitive binding assays. Structural insights were gained through homology modeling, molecular docking, and molecular dynamics simulations, with binding energetics assessed using MM/PBSA. Results showed that OasiCSP12 expression is phase- and sex-specific, being significantly upregulated in gregarious adult antennae. The protein bound selectively to 15 locust body-surface volatiles, including aldehydes and esters. Its structure features a hydrophobic binding cavity where van der Waals interactions, primarily predicted to be mediated by residues Val86, Leu71, and Trp101, likely stabilize ligand complexes. These findings indicate that OasiCSP12 is potentially associated with both chemical perception and phase regulation in O. d. asiaticus, providing a candidate target for developing behavior-based green control strategies against this pest.