"Odor" - what is it, definition of the term
Odor is a volatile chemical stimulus that evaporates at ambient temperature, reaches the nasal epithelium, binds to olfactory receptors, and generates a neural signal interpreted as a smell; its perception depends on molecular structure, concentration, and individual sensitivity, and in entomology these volatile cues serve as attractants or repellents for organisms such as ticks, insects, lice, and fleas.
Detailed information
Volatile chemicals released by arthropods such as ticks, true bugs, lice, and fleas serve as primary cues for locating hosts, mates, and suitable habitats. These compounds, often termed semiochemicals, include carbonyls, aldehydes, and fatty acid derivatives that diffuse into the surrounding air.
Sensory structures on the antennae and palps contain olfactory receptor neurons tuned to specific molecular features. Binding of a volatile molecule to a receptor triggers a neural cascade that results in directed movement toward the source. For example, carbon dioxide and ammonia emitted by mammals attract ticks, while certain short-chain fatty acids guide fleas to the skin surface.
The chemical repertoire varies among species:
- Ticks: phenolic compounds, indole derivatives, and host‑derived steroids.
- True bugs (e.g., bed bugs): aggregation pheromones composed of aldehydes and ketones.
- Lice: cuticular hydrocarbons that signal conspecific presence.
- Fleas: terpenoid attractants and host‑derived lactic acid.
Understanding these odorants enables targeted control strategies. Synthetic analogs function as lures in traps, whereas repellents exploit antagonistic compounds that block receptor activation. Effective formulations combine multiple volatiles to disrupt host‑seeking behavior across the listed arthropods.