The Cotton Bollworm Larvae Use a Highly Expressed Odorant Receptor to Detect a Potent Insect Repellent, (-)-Bornyl...

Area of Science:

• Entomology
• Molecular Biology
• Chemical Ecology

Background:

• Helicoverpa armigera larvae cause significant crop damage by feeding on buds and fruits.
• Olfaction is vital for host plant selection in these larvae, but the underlying molecular mechanisms remain largely unknown.

Purpose of the Study:

• To identify and characterize olfactory receptors involved in larval host selection in Helicoverpa armigera.
• To elucidate the molecular basis of olfactory perception in lepidopteran larvae.

Main Methods:

• Quantitative real-time PCR (qRT-PCR) and in situ hybridization to identify highly expressed odorant receptors.
• Ectopic expression in Drosophila T1 neurons to test ligand specificity.
• CRISPR/Cas9 gene editing to create mutant larvae for behavioral assays.
• Structural modeling and molecular docking to analyze ligand-receptor interactions.

Main Results:

• HarmOr54 was identified as a highly expressed odorant receptor in Helicoverpa armigera larval antennae.
• HarmOr54 specifically responded to (-)-bornyl acetate and 2-ethylhexyl acetate in heterologous systems.
• Larvae with CRISPR/Cas9-generated HarmOr54 mutations exhibited a loss of avoidance behavior towards (-)-bornyl acetate.
• Molecular modeling indicated that (-)-bornyl acetate has a stronger binding affinity to HarmOr54 than 2-ethylhexyl acetate.

Conclusions:

• HarmOr54 plays a significant role in the olfactory perception of (-)-bornyl acetate in Helicoverpa armigera larvae.
• These findings contribute to understanding olfactory mechanisms in lepidopteran larvae.
• The identified receptor and its ligand offer potential targets for novel pest control strategies against larval stages.