Insecticidal activity of five medicinal plant essential oils against the cabbage aphid, Brevicoryne brassicae

Essential oils are volatile mixtures of hydrocarbons with diverse functional groups. In the current study the effect of essential oils from five medicinal plants including Zataria multiflora and Nepeta cataria (Lamiaceae), Tagetes minuta and Artemisia siberi (Asteraceae), and Trachyspermum ammi (Apiaceae) were analyzed using GC-mass spectrometry. The toxicity of these plant essential oils against the adult stage of the cabbage aphid, Brevicoryne brassicae L. (Hemiptera: Aphididae) was studied using a fumigant assay.GC/Mass analysis revealed that the main essential oils varied between species. The most abundant components in N. cataria, Z. multiflora, T. ammi, T. minuta and A. sieberi were 4a-α, 7-β, 7a-α-nepetalactone (76.8%), carvacrol (62.1%), γ-terpinene (27.1%), limonene (13.0%) and artemisia ketone (48.0%) respectively. The fumigant assays showed that all of these essential oils were toxic to B.brassicae in a dose-dependent manner. The essential oils of N. cataria at 126, 63, 31, 16, 8, and 3 μl L-1 air caused 94, 76, 52, 46, 36, and 24% mortality within 24 hours, respectively. The same trend was seen when essential oils of the other plants tested against B. brassicae. These plant essential oils have great potential to be used in integrated pest management especially in greenhouses or other closed systems.