Composition and acaricidal activity of essential oil from Elsholtzia densa Benth against Sarcoptes scabiei mites in vitro

摘要

Plant-based natural products represent an alternative to chemical compounds for the control of mitesin veterinary medicine. Here, the essential oil of Elsholtzia densa (E. densa) Benth was extracted using hydrodistillationat a rate of 1.2%. The chemical composition of the essential oil was determined by gas chromatographymassspectrometry (GC-MS) analysis. The GC-MS analysis indicated that the principal compounds in the volatileoil of the sample were 4-Pyridinol (28.16%) and thymol (26.58%). The acaricidal activity of E. densa oil againstSarcoptes scabiei (S. scabiei) was tested in vitro. Toxicity test data were analysed using a complementary log-log(CLL) model. The E. densa oil was prepared in five concentrations by dilution with liquid paraffin (1, 2, 4, 8 and16 mg/ml) and exhibited strong toxicity against S. scabiei with LT50 values of 16.637, 5.075, 2.884, 1.184 and0.760 h, respectively. The LC50 values were 7.678, 4.623, 2.543, 1.502, 1.298 and 0.981 mg/ml for S. scabiei at 1, 2,4, 8, 16 and 24 h, respectively. Compared to the control, the essential oil showed significant effects against S. scabieiin vitro. At 16 mg/ml, E. densa oil was found to kill all mites within a 16-h period. The results indicate thatE. densa oil possesses potential acaricidal activity in vitro and may be exploited as a novel drug for the effectivecontrol of S. scabiei.