## 2 Results
### Larvicidal, Tarsal, and Fumigation Activity on C. quinquefasciatus  
Our insecticidal assays conducted on _C. quinquefasciatus_ showed both larvicidal and adulticidal activity of the _O. syriacum_ essential oil. Third instar larvae exposed to the essential oil showed LC\({}_{50(90)}\) values of 32.4 and 40.1 mg L\({}^{-1}\), respectively, while the oil major constituent carvacrol achieved LC\({}_{50(90)}\) values of 29.5 and 39.2 mg L\({}^{-1}\), respectively. The positive control \(\alpha\)-cypermethrin had LC\({}_{50(90)}\) values of 0.0008 and 0.0025 mg L\({}^{-1}\), respectively (Table 1). Furthermore, contact toxicity testing the essential oil and its main constituent, carvacrol, on adults assayed through the tarsal test led to LC\({}_{50(90)}\) values of 28.1 and 46.9 \(\mu\)g cm\({}^{-2}\) and 25.5 and 35.8 \(\mu\)g cm\({}^{-2}\), respectively. The LC\({}_{50(90)}\) values obtained testing \(\alpha\)-cypermethrin were 1.22 and 2.18 \(\mu\)g cm\({}^{-2}\), respectively (Table 1). In addition, we evaluated the possible role of fumigation toxicity of _O. syriacum_ essential oil on _C. quinquefasciatus_ adults over time. In fumigating assays, the LC\({}_{50}\) of the essential oil was 12.1 \(\mu\)L L\({}^{-1}\) after 1 h of exposure, strongly decreasing to 1.3 \(\mu\)L L\({}^{-1}\) after 24 h of exposure. LC\({}_{90}\) values were 28.8 and 2.2 \(\mu\)L L\({}^{-1}\), respectively (Table 2). Following a similar trend, the fumigation LC\({}_{50}\) of carvacrol was 8.2 \(\mu\)L L\({}^{-1}\) after 1 h of exposure, strongly decreasing to 0.8 \(\mu\)L L\({}^{-1}\) after 24 h of exposure. Moreover, LC\({}_{90}\) values were 16.3 and 1.5 \(\mu\)L L\({}^{-1}\), respectively (Table 3). Lastly, the lethal time (LT) values were calculated testing four concentrations of _O. syriacum_ essential oil, ranging from 2.5 to 20 \(\mu\)L L\({}^{-1}\); 66 min was the minimum LT\({}_{50}\) value, obtained testing 20 \(\mu\)L L\({}^{-1}\), while the LT\({}_{90}\) was 103 min. Lower concentrations of this essential oil led to higher LT\({}_{50(90)}\) values, namely 117 and 191 min testing 10 \(\mu\)L L\({}^{-1}\), 201 and 408 min testing 5 \(\mu\)L L\({}^{-1}\), and 426 and 789 min testing 2.5 \(\mu\)L L\({}^{-1}\) (Table 3). Figure 1: Anthelmintic activity of the _Origanum syriacum_ essential oil: larvicidal activity against L3 larvae of _Anisakis simplex_ after 24–48 h (**A**), larval penetration was fully inhibited after 1, 12, and 24 h of exposure to the oil, if compared to control wells (**B**). \(\boldsymbol{\cdot}\boldsymbol{\times}\boldsymbol{p}<0.001\) versus control. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Target Insect** & **Unit** & **LC50** & **CI95** & **LC90** & **CI95** & \(\chi^{2}\) \\ \hline \multicolumn{6}{c}{_O. syriacum Essential Oil_} \\ \hline \multicolumn{6}{c}{_O. syriacum Essential Oil_} \\ \hline \multicolumn{6}{c}{_C. quinquefasciatus_} \\ third instar larvae & mg L\({}^{-1}\) & 32.4 & 31.3–33.6 & 40.1 & 38.3–42.3 & 6.396 \(ns\) \\ \hline \multicolumn{6}{c}{_C. quinquefasciatus_} \\ adult females (tarsal & \(\mu\)g cm\({}^{-2}\) & 28.1 & 25.9–30.3 & 46.9 & 42.1–54.1 & 4.698 \(ns\) \\ toxicity test) & & & & & \\ \hline \multicolumn{6}{c}{_C. quinquefasciatus_} \\ third instar larvae & mg L\({}^{-1}\) & 29.5 & 28.3–31.8 & 39.2 & 36.7–42.9 & 5.214 \(ns\) \\ \hline \multicolumn{6}{c}{_C. quinquefasciatus_} \\ adult females (tarsal & \(\mu\)g cm\({}^{-2}\) & 25.5 & 21.2–27.3 & 35.8 & 32.7–41.5 & 3.251 \(ns\) \\ toxicity test) & & & & & \\ \hline \multicolumn{6}{c}{_Positive Control, \(\alpha\)-Cypermethrin_} \\ \hline \multicolumn{6}{c}{_C. quinquefasciatus_} \\ third instar larvae & mg L\({}^{-1}\) & 0.0008 & 0.0006–0.0012 & 0.0025 & 0.0021–0.0032 & 5.235 \(ns\) \\ \hline \multicolumn{6}{c}{_C. quinquefasciatus_} \\ adults (tarsal & \(\mu\)g cm\({}^{-2}\) & 1.22 & 0.95–1.38 & 2.18 & 2.01–2.26 & 3.245 \(ns\) \\ toxicity test) & & & & & \\ \hline \hline \end{tabular}
\end{table}