Biochemical effects and molluscicidal activity of some vegetable oils against adults of land snails

This study aimed to assess the molluscicidal activity of some vegetable oils against adults of land snails. Three oil treatments were investigated: Fresh oil (FO), a blend of sunflower and soybean seeds mixed in a 1:1 ratio, a waste cooking oil (WCO) blend of used sunflower and soybean in the same ratio, and lemon grass volatile oil (LGVO). These treatments were tested against adults of Monacha cartusiana (O. F. Müller) (Gastropod:Hygromiidae), Eobania vermiculata (O. F. Müller) and Theba pisana (O. F. Müller) (Gastropod:Helicidae) snails at concentrations of 7.5, 15, and 30%, respectively, under laboratory conditions. The results revealed that mortality percentages increased with concentration, the highest impact observed at a concentration of 30%. M. cartusiana exhibited the greatest susceptibility, with mortality percentages of 20.00%, 26.67%, and 66.67%, while E. vermiculata showed the lowest sensitivity, and observed with 13.33%, 20.00%, and 26.67% for FO, WCO, and LGVO, respectively after 28 days of treatment. Biochemical investigations demonstrated a significant impact on enzyme activity. WCO treatment caused a reduction in amylase and invertase activities in all species, indicating metabolic disruption. Conversely, LGVO resulted in increased enzyme activity, suggesting physiological stress responses. In M. cartusiana, WCO reduced amylase and invertase activities by up to −11.58% and −19.99%, respectively, while LGVO increased them by up to 27.04% and 9.71% at 7 days of treatment. Finally, the tested oils can be categorized in decreasing order of effectiveness as LGVO > WCO > FO. The differential susceptibility among snail species may be attributed to variations in body size and physiological characteristics.