ABSTRACT
Aims: It is acknowledged that many essential oils isolated from various plants can exert toxic activity against insect species. In the present study, the essential oil from aerial parts of Agastache foeniculum (Pursh) Kuntze (Lamiaceae) evaluated for its larvicidal and physiological effects against the larvae of Tribolium castaneum Herbst. Place and Duration of Study: Place – Department of plant protection, Faculty of agriculture, Guilan university, Rasht, Iran. Duration – May, 2012 to January, 2013. Methodology: The essential oil was isolated from aerial parts of A. foeniculum by hydrodistillation method with a Clevengertype apparatus. In Larvicidal bioassay, five concentrations of the essential oil were prepared with acetone as solvent. Control samples were treated only with pure acetone. Ten same-aged instars were randomly selected, placed with treated diets and kept at 27 ± 2ºC and 60 ± 5% RH. The experiment was repeated four times and insect mortalities were recorded after 24 h. The effects of essential oil on total carbohydrate, lipid and protein contents on the surviving larvae were assessed. Also, the responses of general esterase and glutathione S-transferase as two detoxifying enzymes to essential oil were investigated. Results: A. foeniculum essential oil caused high mortality and the mortality was dose dependent i.e. with increasing of essential oil concentrations more mortality achieved. Furthermore, study on the effect of essential oil on total carbohydrate, lipid and protein contents demonstrated that all of them were decreased with increasing of concentrations. When A. foeniculum essential oil was applied, inhibition of esterase and glutathione Stransferase activities was observed. Conclusion: It has been found that the essential oil of A. foeniculum may produce a great range of biological effects on T. castaneum larvae and can be a potent candidate for such insect pest management.
ABSTRACT
An interest in natural products from plants has been increased due to the disruption of natural biological control systems, undesirable effects on non-target organisms, environmental hazards, and the development of resistance to synthetic insecticides, which are applied in order to reduce the populations of insects. Essential oils (EOs) from plants may be an alternative source of insect control agents, since they constitute a rich source of bioactive compounds that are biodegradable into nontoxic products and potentially suitable for use in integrated management programs. These materials may be applied to food crops shortly before harvest without leaving excessive residues. Furthermore, medically safe of these plant derivatives has emphasized also. For these reasons, much effort has been focused on plant EOs and their constituents as potential sources of insect control agents. In this context, Myrtaceae family would rank among the most important families of plants. In the last few years more and more studies on the insecticidal properties of EOs from Myrtaceae family have been published and it seemed worthwhile to compile them. Therefore, the subject matter of this paper lies on the insecticidal effects of EOs from Myrtaceae and their compounds in insect pest's control. Natural essences of Myrtaceae plants owe its insecticidal action to the presence in its composition of terpenic derivatives such as 1.8-cineole, limonene, linalool, myrcene, terpineol, thymol and α-pinene, which have introduced as potential insecticides. These review indicated that pesticides based on Myrtaceae essential oils could be used in a variety of ways to control a large number of insect pests.