Phytochemical and Insecticidal Study of the Avishan-e-denaii (Thymus daenensis Celak.) Essential Oil against the Melon Aphid (Aphis gossypii Glover)

Abstract

Aphis gossypii Glover (Hemiptera: Aphididae) is one of the most important pests of agriculture worldwide. To control the pest population, research on the use of the environmental and plant-based compounds has increased in recent decades. Essential oils due to volatility and very short-term persistence in the environment, as biocompatible pesticides can be considered as one of the best alternatives to chemical pesticides in aphid’s control. In the current study, phytochemical and insecticidal toxicity of the essential oil from Avishan-e-denaii, Thymus daenensis Celak. was studied against the melon aphid, Aphis gossypii Glover. in the laboratory conditions under 25±2°C, 60±5 % RH and 16L:8D photoperiods. The essential oil was obtained by hydrodistillation method, using Clevenger-type apparatus. Mortality was evaluated at different concentrations that ranging from 0.1 to 0.9 μL/L air, and with three replications at the interim of 24 hours. Also nymph production deterrent effect of the oil at sublethal concentration was studied against parthenogenesis form of aphid. Results indicated that essential oil of T. daenensis is toxic to the A. gossypii. The major components in the oil were 3-Methyl-4-isopropylphenol (26.94 %), thymol (22.40 %), p-cymene (13.81 %), γ-terpinene (6.74 %), borneol (5.24 %) and linalool (4.31 %). Probit analysis showed that the LC50 values for nymphs and adults of A. gossypii were 0.0087 and 0.0016 μl./L-1 air, respectively. Also, degree of nymph production deterrent effect was calculated for essential oil of T. daenensis as 46.49 ± 4.71 %. The overall results showed that the Avishan-e-denaii essential oil has high potential in controlling the melon aphid especially in protected cultivation.