CHEMICAl, ENVIRONMENTAL AND BIOL OGICAl STUDIES OF THE PlANT MOLLUSCICIDE "PHLOMIS AUREA", DECNE FAM LABIATAE

Abstract

The molluscicidal toxicity of the Phlomis aurea weed was studied. The plant parts (leaves & flowers and seed) was extracted by different methods of equeous extraction or with successive organic solvents of increasing prolarity and total ethanol extracts.

It was found that the mollusicidal activity of the tested aqueous extracts against B.alexandrina snail, could be arranged descendingly as follows: decection, suspension, soaking and decoction filtrate.

The petroleum ether extract was more toxic than other extracts against B.alexandrina, having LCso 4 ppm. While the total ethanol having LCso 5 ppm and other extracts were moderately active.

The relationship between sub lethal concentrations of petroleum ether extracts of the plant parts and egglaying capacity of B.alexandrina adult snails was studied. It was found that the sub-lethal concentrations of petroleum ether extracts of the plant parts, generally inhibited egg laying of snails; However, the repeated application of extracts might lead toJhe accumulation of the active ingredients inside the snail reproductive organs.

The ovicidal activity of more toxic extrac.t of tested plant, was markedly lower than that of adult snails. The sensitivity of both miracidia and cercariae of ,S.mansoni• to the plant petroleum ether extracts was nearly the same; However, the highest concentration of either extract showed a similar mortality on both miracidia and cercariae

There was an inverse relationship between concentration and exposure period to produce 100% mortality. The potency of petroleum ether extract was adversely affected by sunlight