Abstract
Mentha longifolia (L.) and Lavandula dentata (L.) (Lamiaceae) are two wild growing folk medicine plants that in Saudi Arabia. This work was conducted to investigate the chemical composition and evaluate the fumigant toxicity of their essential oils against the adults (3-5-day-old) of cowpea beetle, Callosobruchus maculatus (F.) (Coleoptera: Bruchidae). The main compounds in M. longifolia oil were pulegone (74.95%), 1,8-cineole (7.35%), l-menthone (6.62%), and eucarvone (2.68%), while the main constituents in L. dentata oil were camphor (61.43%), fenchone (24.3%), d-fenchol (2.15%), and linalool (1.52%). The two oils showed LC50 values of 4.43 and 7.92 mu l/L air and exhibited antiacetylcholinesterase activity with IC50 values of 1.01 and 9.74 mu l/ml, respectively. The results proved the potential use of these natural materials as effective alternatives to synthetic pesticides.