Insecticidal properties of plant extracts and monoterpenes towards the fourth instars of Spodoptera littoralis Boisd(Lepidoptera : Noctuidae)‎ and adults of Aphisfabae L. (Herniptera: Aphididae)‎

الملخص EN

The extracts of three plants, namely Zygophyllum coccineum L.y Majorana hortensis (Moench) and Mentha microphylla L.

were tested for their insecticidal activity against the fourth instar la ^ ae of the Egyptian cotton leafworm, Spodoptera littoralis and the adults of the bean aphid, Aphis fabae.

All of the tested extracts were found to be toxic against both insects.

However, the degree of toxicity was varied based on plant extract, plant species and inscct species.

Among the tested extracts, petroleum ether extract 0f M.

horiensis (LD50 = 2.

76 ug / larva) was the most potent against 5.

littoralis followed by chloroform extract of the same plant (LD50 = 3.36 |ig/larva).

The petroleum ether and ethanol extracts ofz coccineum showed the less activity against s.

littoralis.

In the case of A.

fabae, the petroleum ether chloroform extracts of ٧٠ hortensis, the petroleum ether and ethanol extracts of M.

microphylla showed pronounced toxic effect with LC50 values of 21, 2.44, 2.

62 and 2.

25 g / 1, respectively.

The essential oil of M.

hortensis was isolated by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS).

Terpinen-4-ol (30.0 %), y-terpinene (11.

3 %), and fram-sabinene hydrate (10.

8 %) were the major components of the oil.

This oil repealed remarkable insecticidal activity against s.

littoralis and A.

fabae.

Repetitive column chromatography of the essential oil of M.

hortensis led to isolate the two major constituents (terpinen-4-ol and Y-terpinene).

The structure of these compounds were determined based on th^ir spectral data of 1H NMR, ”c NMR and MS.

y-Terpinene was more toxic than terp؛nen-4-0؛ towards s.

littoralis and A.

fabae.

The isolated compounds were less toxic than the essential oil against both insects