Contact and fumigant insecticidal actions of plant
essential oils have been well demonstrated against
stored product pests. Among 22 essential oils tested as
fumigants against the bean weevil Acanthoscelides obtectus
(Bruchidae), those of Thymus serpyllum (rich in the
phenols thymol and carvacrol) and Origanum majorama
(rich in terpinen-4-ol) were the most toxic (RegnaultRoger
et al., 1993). In a more detailed study, Shaaya et al.
(1991) evaluated the fumigant toxicity of 28 essential oils
and 10 of their major constituents against four di!erent