Effect of plant essential oils against rophalosiphum padi on wheat and barley

Abstract

The aim of the present study was to evaluate the effect of six EOs against Rhopalosiphum padi L. (Homoptera: Aphididae). This aphid is one of the most important cereal pests worldwide. EOs used in this study were from cumin (Cuminum cyminum L.; Apiaceae), hyssop (Hyssopus officinalis L.; Lamiaceae), costmary (Tanacetum balsamita L. syn. Chrysanthemum balsamita L. Baill; Asteraceae), lovage (Levisticum officinale W.D.J. Koch; Apiaceae), lavander (Lavandula angustifolia Mill; Lamiaceae) and thyme (Thymus vulgaris L.; Lamiaceae). Cultivar ORCF-10, a soft white winter wheat (Triticum aestivum L.) cultivar and barley (Hordeum vulgare L.) cv. 'Alba' were selected for the bioassays. Each EO was diluted with acetone (w/v) at different concentrations ranging from 0.1 % to 1.0 %. Number of R. padi landing on treated or untreated leaves was counted 24 h after the initial aphid transfer. In general, the repellency effect increased as the concentration of EOs increased regardless of treatments with the exception of lovage. Regardless of the substrate and treatment, lower numbers of aphids were observed on treated leaves at higher concentrations compared to the untreated control stressing the repellency effect. This study demonstrated that the EOs of cumin, hyssop, costmary, lavender, and thyme may have potential for aphids control.