Adult Repellency and Larvicidal Activity of Five Plant Essential Oils Against Mosquitoes

The larvicidal activity and repellency of 5 plant essential oils—thyme oil, catnip oil, amyris oil, eucalyptus oil, and cinnamon oil—were tested against 3 mosquito species: Aedes albopictus, Ae. aegypti, and Culex pipiens pallens. Larvicidal activity of these essentials oils was evaluated in the laboratory against 4th instars of each of the 3 mosquito species, and amyris oil demonstrated the greatest inhibitory effect with LC50 values in 24 h of 58 µg/ml (LC90 = 72 µg/ml) for Ae. aegypti, 78 µg/ml (LC90 = 130 µg/ml) for Ae. albopictus, and 77 µg/ml (LC90 = 123 µg/ml) for Cx. p. pallens. The topical repellency of these selected essential oils and deet against laboratory-reared female blood-starved Ae. albopictus was examined. Catnip oil seemed to be the most effective and provided 6-h protection at both concentrations tested (23 and 468 µg/cm2). Thyme oil had the highest effectiveness in repelling this species, but the repellency duration was only 2 h. The applications using these natural product essential oils in mosquito control are discussed.