In Vitro Comparative Study: Toxicity of Calotropis procera, Nerium oleander Extracts, Methomyl, and their mixtures on Monacha obstructa

Abstract

Ethanolic extracts of fresh Osher, Calotropis procera and Daflla, Nerium oleander leaves were assessed in vitro for their molluscicidal activity against the glassy clover snail, Monacha obstructa (Pfeiffer). The evaluation involved both contact and leaf dipping techniques over a 72 hrs. period. Additionally, combinations of each plant extract with methomyl as a chemical pesticide, were tested at a 1:1 ratio (v/v) in order to mitigate the harmful effects of methomyl while maintaining its high molluscicidal activity. Results demonstrated high toxicity of the plant extracts against the target snails, with the contact technique exhibiting greater efficacy than the dipping leaf method for both plant extracts and methomyl. The LC 25 and LC 50 values of C. procera via contact and leaf dipping methods were found to be (8.24 and 13.86) and ( 27.09 and 36.02) ppm, respectively. Similarly, sub-lethal concentrations of N. oleander achieved via the contact method were (12.55 and 19.84) ppm for LC 25 and LC 50 , respectively, while the leaf dipping application yielded LC 25 and LC 50 values of (20.83 and 29.25) ppm, respectively. Methomyl exhibited LC 25 and LC 50 values of (7.68 and 12.88) ppm via the contact method and (27.13 and 37.89) ppm for the leaf dipping method. Furthermore, mixing methomyl with either N. oleander or C. procera extracts resulted in varying rates of mortality among the tested snails, with different combinations leading to different mortality rates over specific time intervals.