Efficacy of some volatile oils against adults of the white garden snail <i>Theba pisana</i> and the brown garden snail <i>Eobania vermiculata</i> (Gastropoda: Helicidae) and their effects on carbohydrate hydrolyzing enzyme activity

The objective of this study is to investigate the molluscicide impacts of some volatile oils, such as geranium oil (Pelargonium graveolens), French lavender oil (Lavandula dentate), and lemon eucalyptus oil (Corymbia citriodora), against adults of Theba pisana (Müller) and Eobania vermiculata (Müller) (Gastropoda: Helicidae) snails at concentrations (7, 14, and 28%). Then, gas chromatography (GC) is a powerful analytical technique utilized to separate, identify, and quantify components in tested volatile oils. Data showed that the maximum effect of mortality percentages was (46.67 and 40.00%) of Lemon eucalyptus oil at the highest concentration after 28 days of T. pisana and E. vermiculata snails, respectively. Furthermore, the outcomes of biochemical investigations explained that Lemon eucalyptus oil for T. pisana snails were reported (-9.69, -9.81 and -8.59%) and (-16.53, -21.37 and -23.53%) of amylase and invertase enzymes, respectively, at the highest concentration, whereas E. vermiculata snails were recorded (-9.13, -6.41 and -5.55%) and (-2.10, -2.54 and -2.61%) of the same enzymes, respectively. Finally, data mentioned that the tested oils can be categorized in declining order of their efficiency as follows: Corymbia citriodora > Lavandula dentate > Pelargonium graveolens on T. pisana followed by E. vermiculata, possibly due to differences in the size of snails.