Botanical biocides. 8 impact of some plant extracts on Biomphalaria alexandrina snails and on Schistosoma mansoni miracidia and cercariae

ABSTRACT

The present work evaluates the molluscicidal, cercaricidal and miracidicidal activities of certain plants extracted by different solvents of increasing polarity [e.g., petroleum ether, chloroform, acetone, ethanol and water]. The data obtained from preliminary screening tests conducted on 20 plant species belonging to 10 different families revealed that the highly potent extracts were obtained from 14 plants [e.g., Ambrosia maritima, Artemisia herba-alba, Nigella sativa, Cymbopogon schoenanthus, Mentha longifolia, Thymus capitatus, Acacia nilotica, Lupinus termis, Syzygium aromaticum, Piper nigrum, Quassia amara, Ammi majus, Ammi visnaga and Pimpinella anisum]. The toxicity results indicated that the petroleum ether extract of A. maritima was the most toxic to Biomphalaria alexandrina snails [LC50=56ppm], while M. longifolia ethanolic one was the least [LC50=500ppm]. The LC50 values of 38 different extracts from 12 plant species revealed the high potency of acetone extract of P. nigrum [LC50 = 37ppm] against cercariae of Schistosoma mansoni, while water extracts of P, nigrum and A. visnaga as well as acetone extract of N. sativa [LC50 = 100ppm] were of low potencies. The toxicity tests against miracidia of Schistosoma mansoni indicated that the petroleum ether extract of T. capitatus was the most toxic [LC50 = 27ppm], while chloroform one of A. visnaga was the least toxic [LC50 = 96ppm]