## 3 Discussion  
The Lebanese accession of _O. sriacum_ investigated here belonged to the carvacrol chemotype. It is worth noting that, based on these results, the carvacrol chemotype is not restricted only to cultivated plants as reported by [PERSON] et al. [50]. In our study, the essential oil from _O. sriacum_ was reported as an effective antiparasitic agent in the fight against anisakiasis, as well as a good larvicidal and adulticidal product to manage mosquito populations. The larvicidal activity of certain essential oils on _A. simplex_ has been established [26; 27; 28; 29; 30; 31; 62]. Though other _Origanum_ species have shown antiparasitic activity on _A. simplex_, _O. sriacum_ seems to be the most promising, as it induces a higher mortality rate of the larvae at lower concentration. For example, a former study showed that _Origanum compactum_ Benth had a LC\({}_{50}\) value of 0.429 mg mL\({}^{-1}\) at 24 h [31], which is more than four-fold lower (i.e., 0.087 mg mL\({}^{-1}\)) for _O. sriacum_. In another study a maximum _A. simplex_ mortality rate as high as 53% was achieved testing _Origanum vulgare_ essential oil [29], which reaches up to 100% for _O. sriacum_ when tested at 0.125 mg mL\({}^{-1}\). All these data suggest that _O. sriacum_ essential oil is highly effective and more potent than essential oils from other _Origanum_ species, with carvacrol being one of the most important compounds responsible for the larvicidal effects. In addition, the results of our assays pointed out that the _O. sriacum_ essential oil treatment fully neutralizes the capacity of _A. simplex_ larvae to penetrate agar, potentially inhibiting host muscle penetration and reducing the pathogenic capacity of the larvae [63]. The main constituents in the essential oil were the monoterpenes carvacrol, \(\gamma\)-terpinene, \(p\)-cymene, and thymol; some of these compounds, in particular, carvacrol and thymol, have recently shown larvicidal effects and acetylcholinesterase-inbibitory activity as a potential mechanism of action [31]. However, the leaf essential oil of _O. sriacum_ studied here showed significantly lower LC\({}_{50}\) values (i.e.,  
Figure 2: Inhibition of the acetylcholinesterase-(AChE) by the _Origanum sriacum_ essential oil over the positive control galantamine. 0.08 and 0.067 mg mL\({}^{-1}\) after 24 h and 48 h, respectively) on _A. simplex_ L3, if compared with those achieved by carvacrol (LC\({}_{50}\) = 0.176 and 0.178 mg mL\({}^{-1}\), after 24 and 48 h, respectively) [31], outlining the potential synergistic effects due to the presence of minor constituents of the Lebanese oregano oil, a topic which surely deserves further research [62; 64]. Furthermore, carvacrol and thymol are commonly found in _Origanum_ species, being responsible for the antimicrobial activities of these plants [65; 66]. In addition, carvacrol is more effective than its isomer thymol as a larvicidal agent and AChE inhibitor [31; 67; 68]. The increasing popularity of eating raw-undercooked fish together with certain fishing and processing procedures favoring the parasite cycle (e.g., fish evisceration at sea) contributes to a higher prevalence of anisakiasis. Currently, these types of gastrointestinal parasitic diseases are not pharmacologically treated, but considering results presented herein, _Origanum_ essential oils, and particularly _O. syriacum_, might be industrially exploited with the aim of treating or preventing anisakiasis or as a fish food additive to avoid larvae propagation after evisceration. Concerning the insecticidal activity of essential oils, mosquito larvicides with an LC\({}_{50}\) lower than 100 ppm could be considered as promising [69]. In addition, this perspective enhances the possibility of growing such plants in monocultures where, through the application of appropriate cultivation technologies, sufficient biomass can be produced to extract essential oils [70].