chemorepellent

A chemorepellent is a chemical substance that induces avoidance behavior in an organism through chemical cues. In ecology and toxicology, chemorepellents act on sensory systems such as the olfactory or gustatory pathways to reduce contact with a resource, host, or area. They are distinct from attractants, which draw organisms toward a source.

Mechanism and examples: Many chemorepellents work by masking attractive odors, stimulating aversive receptors, or overwhelming the sensory system with irritant or repellent signals. Insects are a common target; widely used compounds include synthetic repellents such as DEET and picaridin, as well as plant-derived products like citronella and eucalyptus oils. Capsaicin-based products deter mammals by causing a burning sensation on contact. Some repellents function through spatial effects, creating an odor field that discourages approaches without direct application to the body.

Applications: Chemorepellents are used in public health for vector control, in consumer products for personal protection, and in agriculture and stored-product protection to reduce pest damage. Methods include topical repellents, treated textiles, repellant-impregnated nets, and spatial repellents such as coils, lamps, or sprays that create a protective zone around people or crops.

Limitations and safety: Effectiveness depends on species, dose, dose-response, and environmental conditions; pests can adapt or become tolerant. Non-target effects and environmental impact are considerations for regulators and users. Proper labeling, safety precautions, and adherence to regulations are essential when applying chemorepellents.