Insecticidal and acaricidal effect of three Lamiaceae plant essential oils against Tetranychus urticae Koch and Bemisia tabaci Genn.

Tetranychus urticae Koch (Acari: Tetranychidae) and Bemisia tabaci Germ. (Homoptera: Aleyrodidae) are two economically important pests of greenhouse vegetables and ornamentals. The management is commonly done based on repetitive applications of chemicals, resulting in environmental pollution and resistance in pest population. In the present study, essential oil vapours from Micromeria fruticosa L., Nepeta racemosa L. and Origanum vulgare L. (Lamiaceae) were tested for toxicities against the nymphs and/or adults of T urticae and the adults of B. tabaci. Amounts of the essential oils applied were 2, 4, 6 and 8 mu l in each of the desiccators with 4 1 capacity, corresponding to 0.5, 1, 1.5 and 2 mu l/l air. The essential oil vapours of all three plant species caused the highest mortality in 2 mu l/l air doses and at 120 h of exposure in both of two pests' species. In general, higher mortality was observed as the doses of essential oils and exposure period increased. T urticae was more tolerant than B. tabaci at all doses of essential oils in all times. The data may suggest that essential oils of all three plants have potential to be used for management of T urticae and B. tabaci pests in greenhouse conditions. (c) 2005 Elsevier B.V. All rights reserved.