Peripheral olfactory signaling in insects

• Olfactory signal transduction occurs in sensillar odorant receptor neurons.
• Distinct chemical space is covered by specific chemoreceptor families.
• Olfactory gene families evolve in a linage specific way by rapid gain and loss.
• Odorant receptors are presumed to have evolved with the emergence of winged insects.
• Conservation of Orco provides opportunities to design novel insect control methods.

Olfactory signaling is a crucial component in the life history of insects. The development of precise and parallel mechanisms to analyze the tremendous amount of chemical information from the environment and other sources has been essential to their evolutionary success. Considerable progress has been made in the study of insect olfaction fueled by bioinformatics-based utilization of genomics along with rapid advances in functional analyses. Here we review recent progress in our rapidly emerging understanding of insect peripheral sensory reception and signal transduction. These studies reveal that the nearly unlimited chemical space insects encounter is covered by distinct chemosensory receptor repertoires that are generally derived by species-specific, rapid gene gain and loss, reflecting the evolutionary consequences of adaptation to meet their specific biological needs. While diverse molecular mechanisms have been put forth, often in the context of controversial models, the characterization of the ubiquitous, highly conserved and insect-specific Orco odorant receptor co-receptor has opened the door to the design and development of novel insect control methods to target agricultural pests, disease vectors and even nuisance insects.