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As a result of screening a large number of essential oils from Israeli aromatic plants and their biologically active constituents, we isolated two oils with high activity against several stored-product insects. In this study the effect of these compounds on the acetylcholinesterase and the octopamine systems in insects was studied in order to elucidate their mode of action. Inhibition of acetylcholinesterase activity in vitro was evident only at high concentrations (10(-3) M) and could not account effectively for the low-dose mortality for some stored-product insects observed in vivo. However, the essential oil constituents were found to cause a significant increase in the levels of the intracellular messenger, cyclic AMP of abdominal epidermal tissue in the model insect, Helicoverpa armigera Hübn. The effect was significant even at low, physiological concentrations (10(-8) M) when tested directly on abdominal epidermal tissue preparations in vitro. This intracellular response was found to resemble closely the significant increases in the levels of the cyclic AMP of abdominal epidermal tissue due to treatment with the neurotransmitter/neuromodulator, octopamine. Subsequent treatment with the octopaminergic antagonist, phentolamine, effectively inhibited the cyclic AMP levels induced by essential oil treatment, indicating possible competitive activation of octopaminergic receptors by essential oil constituents.

Type

Journal article

Journal

Pest management science

Publication Date

11/2002

Volume

58

Pages

1101 - 1106

Addresses

ARO, Volcani Center, Institute for Technology and Storage of Agricultural Products, Department of Stored Products, PO Box 6, Bet Dagan 50250, Israel.

Keywords

Animals, Insects, Beetles, Lepidoptera, Plants, Octopamine, Terpenes, Phentolamine, Acetylcholinesterase, Oils, Volatile, Receptors, Biogenic Amine, Cyclic AMP, Cholinesterase Inhibitors, Pest Control, Larva, Cyclohexenes