Chemical composition and toxicity of the essential oils of lippia citriodora from two different locations against rhyzopertha dominica and tribolium castaneum

Abstract

The lesser grain borer, Rhyzopertha dominica (F.), and the red flour beetle, Tribolium castaneum (Herbst), are among broad-based damaging insect pests of agricultural stored products. Because of several side-effects of conventional chemical insecticides to the human health, non-target organisms, and environment, searching for and introducing healthy, inexpensive, accessible and efficient agents is necessary. In the present study, chemical profiles and fumigant toxicity of the essential oils isolated from L. citriodora against R. dominica and T. castaneum were evaluated. Chemical compositions of L. citriodora essential oils from two different Iranian regions including Germi and Parsabad was evaluated by gas chromatography–mass spectrometry (GC-MS) and it was found that the terpenic compounds such as caryophyllene oxide, citral, limonene, and neral has the high amount in both oil. Some components such as sabinene, sulcatone, and β-ocimene were only identified in the essential oil from Germi region while some others such as verbenone, camphor, borneol with considerable amount in Parsabad region had not any trace in Germi' origin essential oil. The results of bioassays showed that the essential oils of L. citriodora from both regions had significant fumigant toxicity against the adults of R. dominica and T. castaneum. In general, essential oils’ concentrations and exposure times had direct positive effects on the observed mortality. According to the results of present study, the terpene rich L. citriodora essential oils from two Iranian regions (Germi and Parsabad) have a high potential for the management of R. dominica and T. castaneum.