Catnip Oil, Monoterpenes Carvacrol, and Citronellol as an Effective Repellent Against Cimex lectularius (Hemiptera: Cimicidae).

The common bed bug (Cimex lectularius L.) is an obligate blood-feeding insect that spreads easily through human activity. Catnip (Nepeta cataria L.) oil has emerged as a promising natural repellent for bed bugs, but previous studies have been limited to laboratory conditions. In this study, we assessed the effectiveness of a catnip-based formulation (20% catnip CCC oil: 10% catnip oil cultivar CR9, 5% carvacrol, 5% citronellol) applied to fabric against bed bugs using simulated field tests, a human finger stimulus test, and field trials. N-Diethyl-meta-toluamide (DEET) was included as a benchmark in the simulated field test. In these tests, both 20% catnip CCC oil and 20% DEET achieved >94% repellency within 24 h, with comparable performance after 2-3 d of aging. After 5 d, 20% catnip CCC oil showed significantly reduced repellency compared to DEET. In the human finger stimulus test, 20% catnip CCC oil remained effective for up to 6 d, whereas in infested apartments, significant repellency lasted only one day. These findings suggest that 20% catnip CCC oil applied to fabric can provide short-term protection against bed bug introductions under natural conditions. Future work should explore optimized barrier dimensions and slow-release formulations to extend efficacy.