Chemical compositions and insecticidal effects of essential oils isolated from Achillea gypsicola, Satureja hortensis, Origanum acutidens and Hypericum scabrum against broadbean weevil (Bruchus dentipes)

Abstract

The essential oils of aerial parts of Achillea gypsicola Hub.-Mor., Hypericum scabrum L, Satureja hortensis L, and Origanum acutidens (Hand.-Mazz.) Letswaart were analyzed in this study by GC and GC-MS and their oils were tested for toxicity against broadbean weevil (Bruchus dentipes). A. gypsicola oil contained camphor (40.17%), 1,8-cineole (22.01%), piperitone (11.29%), borneol (9.50%) and alpha-terpineol (1.56%) as major components. A total of 74 components were identified by GC-MS in H. scabrum oil. including a-pinene (9.26%), terpinen-4-ol (5.12%), camphor (5.94%), delta-cadinene (4.52%), pulegone (4.45%),), gamma-muurolene (4.12%), pinocarvone (3.97%) and beta-caryophyllene (3.42%) as predominant components. The essential oils of O. acutidens and S. hortensis were characterized by high contents of carvacrol (86.99% and 55.74%), gamma-terpinene (0.71% and 20.94%), p-cymene (1.95% and 12.30%), alpha-terpinene (0.13% and 2.04%) and beta-caryophyllene (1.30% and 1.08%). All of the essential oils were toxic to adults of B. dentipes and insect mortality increased with increasing concentration of each oil. The oils (20 pi dose) brought about 100% mortality in 36 h. Although desirable insecticidal activities against the pest were achieved with the oils from all four plant species, S. hortensis and O. acutidens oils were more effective, particularly after 6 h of treatment. The current results concluded that the essential oils, in particular O. acutidens and S. hortensis oils, may be used as potential botanical insecticides against B. dentipes. (C) 2011 Elsevier B.V. All rights reserved.