Insect Repellant

Disease / Phenomenon

Insect repellents are substances that discourage biting arthropods — mosquitoes, ticks, fleas, biting flies, and midges — from landing on or feeding upon a host. They matter far beyond nuisance avoidance: mosquitoes and ticks transmit malaria, dengue, Zika, chikungunya, West Nile virus, Lyme disease, and other serious infections, so effective repellency is a frontline public health measure. Repellents differ fundamentally from insecticides in that they alter behavior rather than kill, working at a distance by disrupting the sensory cues insects use to locate a blood meal. Practical performance depends on the active compound, its concentration, the formulation's volatility and skin retention, ambient temperature, perspiration, and the particular species involved.

Host-seeking insects navigate using carbon dioxide plumes, body heat, moisture, and skin volatiles such as lactic acid, ammonia, and short-chain fatty acids, detected by odorant receptors, ionotropic receptors, and gustatory receptors on the antennae and maxillary palps. Repellent compounds interfere with this system — masking or confusing odorant signals, blocking receptor activation, or stimulating avoidance channels such as TRPA1. Synthetic actives including DEET and picaridin operate largely on odorant coreceptor signaling, while plant-derived terpenoids such as citronellal, geraniol, eugenol, limonene, and para-menthane-3,8-diol act through overlapping chemosensory routes. This page maps those mechanisms.