# SNMP1 is critical for sensitive detection of the desert locust aromatic courtship inhibition pheromone phenylacetonitrile

## TL;DR

This study shows that SNMP1 is essential for detecting the aromatic pheromone PAN in desert locusts, influencing their reproductive behaviors.

## Contribution

The study reveals that SNMP1 is critical for detecting aromatic pheromones in hemimetabolous insects, expanding its known role beyond long-chain aliphatic substances.

## Key findings

- SNMP1-deficient locusts showed significantly reduced electrical responses to PAN in electroantennography and single sensillum recordings.
- Calcium imaging showed reduced activation of brain projection neurons in SNMP1−/− locusts exposed to PAN.
- Behavioral experiments showed altered PAN-induced pairing and mate choice in SNMP1−/− locusts.

## Abstract

Accurate detection of pheromones is crucial for chemical communication and reproduction in insects. In holometabolous flies and moths, the sensory neuron membrane protein 1 (SNMP1) is essential for detecting long-chain aliphatic pheromones by olfactory neurons. However, its function in hemimetabolous insects and its role for detecting pheromones of a different chemical nature remain elusive. Therefore, we investigated the relevance of SNMP1 for pheromone detection in a hemimetabolous insect pest of considerable economic importance, the desert locust Schistocerca gregaria, which moreover employs the aromatic pheromone phenylacetonitrile (PAN) to govern reproductive behaviors.

Employing CRISPR/Cas-mediated gene editing, a mutant locust line lacking functional SNMP1 was established. In electroantennography experiments and single sensillum recordings, we found significantly decreased electrical responses to PAN in SNMP1-deficient (SNMP1−/−) locusts. Moreover, calcium imaging in the antennal lobe of the brain revealed a substantially reduced activation of projection neurons in SNMP1−/− individuals upon exposure to PAN, indicating that the diminished antennal responsiveness to PAN in mutants affects pheromone-evoked neuronal activity in the brain. Furthermore, in behavioral experiments, PAN-induced effects on pairing and mate choice were altered in SNMP1−/− locusts.

Our findings emphasize the importance of SNMP1 for chemical communication in a hemimetabolous insect pest. Moreover, they show that SNMP1 plays a crucial role in pheromone detection that goes beyond long-chain aliphatic substances and includes aromatic compounds controlling reproductive behaviors.

The online version contains supplementary material available at 10.1186/s12915-024-01941-x.