When insects smell like plants: how sensory bias shapes insect pheromone evolution.

Insects produce a vast diversity of sex pheromone compounds despite strong stabilizing selection on species-specific signals. In multiple insect lineages, these pheromones chemically resemble the volatiles produced by plants. Here, I propose that adaptation of insect sensory systems to plant chemistry biases the origin and diversification of insect pheromones. Repeated independent recruitment of plant-like compounds, either through sequestration or de novo biosynthesis, suggests that pheromone evolution can be shaped by ecological interactions. Receptors with dual roles in host detection and pheromone detection may be functionally constrained, further influencing signal diversification and receptor specialization. This framework links sensory biases with macroevolutionary patterns, generating testable predictions about how sensory biases shape insect pheromone evolution.