Fumigant Toxicity and Feeding Deterrent Activity of Essential Oils from Lavandula dentata, Juniperus procera, and Mentha longifolia against the Land Snail Monacha obstructa

Land mollusks are one of the most destructive agricultural pests worldwide, the management of which depends on synthetic molluscicides. However, many of these molluscicides are harmful to nontarget organisms. Hence, there is a need to develop alternative ecofriendly mollus-cicides that are less impactful toward nontarget organisms. So, an investigation into the fumigant toxicity and feeding deterrent effect of essential oils (EOs) from Lavandula dentata L. (Lamiaceae), Juniperus procera Hochst. (Cupressaceae), and Mentha longifolia (L.) Huds. (Lamiaceae) against the land snail Monacha obstructa (Pfeiffer, 1842) (Hygromiidae) was performed. L. dentata EO exhibited the highest fumigant toxicity with LC₅₀ values of 8.68 µL/L air and 7.24 µL/L air after 24 h and 48 h exposure periods, respectively. Its main components were camphor, 1,8-cineole, fenchone, and β-myrecene. The fumigant toxicity of J. procera EO was lower than that of L. dentata, with LC₅₀ values of 25.63 µL/L air and 20.11 µL/L air after 24 h and 48 h exposure periods, respectively. The major constituents of J. procera EO were α-pinene, p-cymene, and β-ocimene. The analysis of M. longifolia EO showed that pulegone, and menthol were the major constituents. However, it displayed no fumigant toxicity up to 50 µL/L air. The three EOs exhibited a strong feeding deterrent effect at sublethal concentrations. The EOs extracted from L. dentata, J. procera and M. longifolia are promising ecofriendly botanical molluscicides against the land snail M. obstructa.