Pheromone Receptor Knock-Out Affects Pheromone Detection and Brain Structure in a Moth

Area of Science:

• Insect neurobiology
• Molecular genetics
• Chemical ecology

Background:

• Sex pheromone receptors are vital for insect reproduction and species isolation.
• Functional studies of moth pheromone receptors are common, but loss-of-function investigations are scarce.
• The influence of pheromone receptors on macroglomeruli development in the antennal lobe remains unknown.

Purpose of the Study:

• To investigate the role of a specific sex pheromone receptor in the development of macroglomeruli in the moth *Spodoptera littoralis*.
• To analyze the impact of receptor knockout on neuronal responses and brain structure.

Main Methods:

• CRISPR-Cas9 gene editing was employed to knock out the primary sex pheromone receptor in *Spodoptera littoralis*.
• Electrophysiological recordings assessed antennal neuron responses.
• Neuroanatomical analysis examined macroglomeruli structure in the antennal lobe.

Main Results:

• Receptor inactivation specifically altered antennal neuron responses to the pheromone.
• The number of macroglomeruli remained unaffected.
• The size of the macroglomerulus processing the main pheromone component was significantly reduced.

Conclusions:

• This study provides the first evidence linking a moth pheromone receptor to macroglomeruli development.
• The observed neuroanatomical changes are likely due to reduced neuronal activity and connectivity.
• Odorant receptors play a role in insect neurodevelopment beyond signal transduction.