Insecticidal activity of essential oils to the tobacco cutworm, Spodoptera litura

Twenty-one essential oils were tested for insecticidal activity via topical administration to third instar larvae of the tobacco cutworm, Spodoptera litura. Oils of Satureia hortensis, Thymus serpyllum and Origanum creticum produced > 90% larval mortality at 24 h at a dose of 100 mug per larva. The LD50 value for S. hortensis (48.4 mug) was comparable to that for Thymus vulgaris (46.9 mug). The monoterpenoid phenols thymol and carvacrol, major constituents of the oils of Thymus and Satureia species, likely account for the insecticidal action of the species. (C) 2001 Elsevier Science B.V. All rights reserved.