Entomologia Experimentalis et Applicata (2009) 131, 225-232

Mostafa A. Abbassy, Samir A.M. Abdelgaleil and Rasha Y.A. Rabie (2009)
Insecticidal and synergistic effects of Majorana hortensis essential oil and some of its major constituents
Entomologia Experimentalis et Applicata 131 (3), 225-232
Abstract: The essential oil from leaves of Majorana hortensis Moench (Lamiaceae) was isolated by hydrodistillation with a yield of 1.6% (wt/wt). The insecticidal activity of the oil was evaluated against fourth instars of Spodoptera littoralis Boisduval (Lepidoptera: Noctuidae) and adults of Aphis fabae L. (Hemiptera: Aphididae). The oil showed a remarkable toxic effect against S. littoralis in a topical application assay (LD₅₀ = 2.48 μg per larva) and in a residual film assay (LC₅₀ = 3.14 g/l). The oil of M. hortensis also exhibited a pronounced toxic effect against A. fabae adults with LC₅₀ values of 1.86 and 2.27 g/l in rapid dipping and residual film assays, respectively. Gas chromatography-mass spectrometry analyses of M. hortensis essential oils revealed the presence of 31 compounds and the main components were terpinen-4-ol (30.0%), gamma-terpinene (11.3%), and trans-sabinene hydrate (10.8%). Repeated column chromatography of M. hortensis oil on silica gel led to the isolation of two major constituents, which were characterized based on ¹H-nuclear magnetic resonance and mass spectrometric data, as terpinen-4-ol and gamma-terpinene. These two components were examined for their insecticidal and synergistic activities towards S. littoralis and A. fabae. Terpinen-4-ol and gamma-terpinene exhibited a significant insecticidal activity against both insects, but gamma-terpinene was more toxic than terpinen-4-ol. When tested in a binary mixture with the synthetic insecticides profenofos and methomyl, it was found that both compounds enhanced the insecticidal activity of these insecticides by two- to threefold. These results show that terpinen-4-ol and gamma-terpinene have a synergistic effect on the insecticidal activities of synthetic insecticides profenofos and methomyl.
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Link to article at publishers website
Database assignments for author(s): Samir A.M. Abdelgaleil

Research topic(s) for pests/diseases/weeds:
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Aphis fabae
	Spodoptera littoralis