Repellency of aromatic medicinal plant extracts and a steam distillate to Aedes aegypti.

The repellent activity of methanol extracts from 23 aromatic medicinal plant species and a steam distillate against female blood-starved Aedes aegypti was examined in the laboratory by skin test and compared with that of N,N-diethyl-m-toluamide (deet). Responses varied according to plant species. At a dose of 0.1 mg/cm2, the repellency of extracts of Cinnamomum cassia bark (91%), Nardostachys chinensis rhizome (81%), Paeonia suffruticosa root bark (80%), and Cinnamomum camphora steam distillate (94%) was comparable to deet (82%). The duration of the effectiveness for extracts from C. cassia bark and N. chinensis rhizome was comparable to deet and lasted for approximately 1 h. Relatively short duration of repellency was observed in P. suffruticosa root bark extract and C. camphora steam distillate. The plants described merit further study as potential mosquito repellent agents.