Allelopathic and insecticidal activities of essential oil of Dracocephalum kotschyi Boiss. from Iran: A new chemotype with highest limonene-10-al and limonene

The aim of present study is to introduce a new chemotype with high allelopathic and insecticidal activities. This chemotype corresponds to the aerial flowering parts of Dracocephalum kotschyi, gathered from its natural habitat in the Kansar-Isfahan of Iran. The most important property of this chemotype is a high amount of essential oil (EO) with an important percentage of limonene-10-al and limonene. According to hierarchical cluster analysis (HCA) and principal component analysis (PCA), present EO formed individual group separating from other E0s, those reported in literature. The results obtained from the herbicidal assays indicate that the EO of D. kotschyi exerts inhibitory effects on seed germination and seedling growth of Amaranthus retrollexus L. and Chenopodium album L In addition, the plant EO containing the identified compounds showed significant insecticidal activity against green peach aphid, Myzus persicae Sulz. Results of ANOVA and Probit analysis of insecticidal assays with six concentrations of EO (0, 2, 5, 10, 20, and 40 mu l l(-1)) on mortality showed a concentration-dependent response. EO of plant showed high potential of insecticidal activity (LC50 = 4.40, 1.44, and 0.27 mu l l(-1); LC90 = 22.24, 6.50, and 2.35 mu l l(-1) after 24, 48, and 72 h, respectively). It seems that EO from new chemotype of D. kotschyi show considerable promise as natural industrial herbicide and insecticide. (C) 2015 Elsevier B.V. All rights reserved.