Molecular genetics and evolution of pheromone biosynthesis in Lepidoptera

Area of Science:

• Evolutionary Biology
• Chemical Ecology
• Genetics

Background:

• Moths (Insecta: Lepidoptera) utilize diverse pheromones for mating, yet the narrow signal/response channel presents a puzzle for signal evolution.
• Closely related species often use distinct pheromone blends, raising questions about how major biosynthetic pathway shifts occur within mate recognition systems.

Purpose of the Study:

• To investigate the evolutionary mechanisms behind pheromone blend divergence in moth species.
• To test the hypothesis that activation of existing desaturase enzymes drives major shifts in pheromone composition.
• To explore the role of gene evolution, specifically the birth-and-death model, in moth speciation.

Main Methods:

• Analysis of pheromone biosynthetic pathways in various moth species, focusing on desaturase enzymes.
• Examination of mRNA activation within pheromone glands to identify shifts in enzyme function.
• Comparative genomic analysis of desaturase genes in related species, including Asian and European corn borers.

Main Results:

• Activation of different desaturases from existing mRNA provides a mechanism for rapid, significant changes in moth pheromone blends.
• Moth sex-pheromone desaturase genes appear to evolve under a birth-and-death model, involving gene duplication, loss, and pseudogenization.
• This evolutionary process is implicated in the speciation of moth lineages, exemplified by Ostrinia species.

Conclusions:

• The activation of pre-existing desaturase genes is a key driver of pheromone evolution and divergence in moths.
• The birth-and-death evolution of desaturase gene families contributes to moth speciation.
• Understanding these mechanisms provides insight into the evolution of chemical communication in insects.