Composition and molluscicidal potential of four essential oils against <i>Theba pisana</i> snail (Müller, 1774)

Abstract There is a growing global interest in replacing conventional pesticides with eco‐friendly alternatives. In this work, we extracted four essential oils (EOs) from leaves of pink pepper ( Schinus terebinthifolius , ST), eucalyptus ( Eucalyptus camaldulensis , EC), bark of cinnamon ( Cinnamomum spp., C), and peel of orange ( Citrus sinensis , CS) and identified their constituents by GC–MS. We also investigated their contact toxicity against an important agricultural pest, Theba pisana . The co‐toxicity factor for STEO with the other three essential oils was determined. The main components were α ‐pinene, β ‐phellandrene, and o‐cymene (STEO); durene, α ‐pinene, and eucalyptol (ECEO); cinnamaldehyde, (E)‐, cinnamaldehyde dimethyl acetal (CEO); and D‐limonene, β ‐myrcene, and terpinen‐4‐ol (CSEO). STEO was the most effective, with LD 50 of 3.2 μg/g BW, followed by ECEO, CEO, and CSEO presenting LD 50 values equaling 270.2, 272.6, and 2043.4 μg/g BW, respectively with significance between STEO and the other essential oils at the p ≤.05. Combination of STEO with CEO led to a potentiation effect, with the co‐toxicity factor ranging from 40 to 180, based on the dose and time of exposure. In contrast, its mixture with CSEO showed an antagonistic effect, with the co‐toxicity factor varying between −33.35 and −87.5. STEO as a natural, eco‐friendly molluscicide was more effective than traditional, harmful molluscicides by tens of folds, and has the potential to be developed as a molluscicide, particularly in closed areas such as greenhouses.