Effect of ethanol extracts from the plants, anagallis arvensis and zingiber officinale and their mixtures against lymnaea natalensis, the snail vector of fasciola gigantica

ABSTRACT

Ethanol extracts of Anagallis arvensis and Zingiber officinale and their mixtures were tested against Lymnaea natalensis snails and their eggs. In addition, the effect of prolonged exposure [4 weeks] of these snails to the tested extracts and their mixtures on snail's survival, fecundity and tissues of their hermaphrodite gland was evaluated. It was observed that A. arvensis extract was more toxic to the snails and their eggs, after 24 hours exposure, with LC90 of 10.57 ppm and 133.1ppm, respectively. Prolonged exposure of snails to the sublethal concentrations [LC25 and LC50] from each plant extract caused a considerably high cumulative death rate, being 83.3% and 90% by the 4[th] week in the case of LC50 from A. arvensis and Z. officinale, respectively. On the other hand, simultaneous mixing of these concentrations reduced the cumulative death rate of snails to be 46.7% in LC25 mixture and approximately diminished it in LC50 mixture [10% death only]. The snails' fecundity post prolonged exposure to the tested extracts and their mixtures was significantly less than that of control group. This was supported by histological sections of snail's hermaphrodite gland that suffered from degeneration in gametogenic stages and low number of oogonia. For binary combinations of A. arvensis and Z. officinale [LC25 or LC50 mixtures], it was noticed that 24 hours of snails' exposure to Z. officinale pre-exposure to A. arvensis highly improved their molluscicidal potency, but vice versa approximately diminished it