The biochemical process of pheromone component degradation from body and antenna is cardinal for olfaction by permeating sensitivity to incoming pheromones. Substrate-specific enzymes synthesized by moths are responsible for degradation of pheromone components in the body. Studies conducted using pheromone analogues and 3H-labeled pheromones coupled with the application of radioactive probes have steered the discovery of epoxide hydrolase, esterase, and aldehyde dehydrogenase activities in the degradation process in moths. For instance, epoxide hydrolase located in the antennae of adult males metabolize the sex pheromone of gypsy moth. The metabolic process occurs through the addition of water molecules to strained 3 membered ring epoxides by epoxide hydrolases. In the case of silk moths, esterase which degraded about 25% of pheromone absorbed from air within five minutes was elucidated. The pheromone esterase demonstrated sex and tissue specificity. Under normal concentrations, the estimated maximum half-life of the pheromone is 15 msec. The difference in activity affirms that the pheromone rapidly strives to minimize stimuli noise. The degradation of the aldehyde contained in Anteraea polyphemus is also achieved through the action of an antenna-specific aldehyde oxidase.
Moreover, in Choristoneura fumiferana, the degradation of (E)-11-tetradecenal to (E)-11-tetradecenoic acid was observed. A unique antennae-specific aldehyde oxidase degrades bombykal, and bombykol has been reported in Bombyx mori. Holistically, the metabolism occurs through the chemical modification of a substrate to a water-soluble intermediated; a phenomenon referred to us odorant metabolism. The chemical modification may involve the addition of oxygen or the removal of electrons. The addition of a hydroxyl group by an enzyme P450-dependent monooxygenases is a common first metabolic step. Subsequent oxidations of the intermediate complete the degradation process. Each molecule contained in the pheromone blend antennal enzyme capable of degrading it, thus yielding the assertion that pheromone degradation plays a cardinal role in pheromone detection and perception. Antennae-specific pheromones may be found in both male and female moth. The pheromones are both for perception and odorant purposes. The bottom line is that pheromone-clearance is vital for olfaction and perception of new stimuli.