Essential Oil Variability of Azorean Cryptomeria japonica Leaves under Different Distillation Methods, Part 2: Molluscicidal Activity and Brine Shrimp Lethality

This study reports on the in vivo molluscicidal activity and Artemia salina lethality of Azorean Cryptomeria japonica leaf (CJL) essential oils (EOs) obtained by hydrodistillation (HD) and water-steam distillation (WSD) techniques, especially in light of the recent focus on the use of forestry and wood industry residues in a sustainable world economy. Molluscicidal activity was performed during several life stages of Radix peregra by the immersion method, under laboratory conditions. A first screening through a single-dose bioassay revealed that both EOs were highly active towards eggs, juveniles and adult snails (ca. 100% mortality). Concentration- and time-toxicity assays were carried out only on adult snails to determine the lethal parameters (LC50;90 and LT50;90). The LC50 values were 33 and 62 mu g/mL for EO-WSD and EO-HD, respectively, after 48 h. The LT50 of EO-WSD required only 21 h for both 16 h and continous exposure periods, while that of EO-HD was slighty superior (21.8-25.6 h). Although not significant, EO-WSD was also slightly more toxic against A. salina than EO-HD (LC50 = 98 and 115 mu g/mL after 24 h, respectively). In conclusion, Azorean CJL EOs, which are rich in alpha-pinene (mostly EO-WSD), have huge potential to be used as safe raw materials for the development of natural molluscicide products to control snails responsible for transmitting fascioliasis.