Bioactivity of Linalool Against Culex quinquefasciatus: Repellent and Larvicidal Evaluations

Mosquitoes spread a range of life-threatening illnesses such as malaria, dengue, zika virus, chikungunya, yellow fever, and many others, and cause up to 1 million deaths and 1 billion infections across the world every year. There has been growing interest in plant-based repellents that display bioactive compounds with insecticidal and repellent activities. In this review, the focus is on a natural monoterpene that has gained therapeutic properties, including antifungal, antibacterial, antioxidant, anticancer, and neuropharmacological activity, including anti-anxiety and sedative activity. The efficacy of linalool was assayed against mosquitoes in larvicidal and repellent bioassays. Larvicidal assays exhibited dose-dependent mortality: 82% at 1%, 87.4% at 2%, and 90.8% at 4% concentration after 24 h. Repellency cage assays exhibited good initial efficacy, with 1% linalool repelling 82.2% of mosquitoes, 2% repelling 81.8%, and 4% repelling 90.8%, very close to DEET's (N,N-diethyl-meta-toluamide) 93.4%. After 210 min, the 4% concentration had 82.2% repellency, while DEET had 89.6%. Tunnel tests revealed 4% linalool provided 90.2% repellency at 1 h and 84% at 3 h. The findings show that linalool, especially at high levels, is extremely effective as a repellent and larvicide. Its activity is as effective as that of DEET, the present synthetic repellent, and hence linalool can be utilized as an effective natural substitute for long-lasting mosquito control.