Abstract
The acaricidal activities of 12 commercial constituents derived from Eugenia caryophyllata leaf oils against Dermatophagoides farinae, D. pteronyssinus and Tyrophagus putrescentiae adults were examined using an impregnated fabric disk application and compared with that of the commercial benzyl benzoate as synthetic acaricide. On the basis of $LD_{50}$ values, the most toxic compound was methyl eugenol ($4.13\;{\mu}g/cm^2$), followed by methyl isoeugenol ($4.19\;{\mu}g/cm^2$), isoeugenol ($4.29\;{\mu}g/cm^2$), eugenol ($4.94\;{\mu}g/cm^2$), and acetyl eugenol ($13.91\;{\mu}g/cm^2$) against D. farinae. In the case of D. pteronyssinus, isoeugenol ($2.93\;{\mu}g/cm^2$) was the most toxic, followed by methyl isoeugenol ($3.28\;{\mu}g/cm^2$), methyl eugenol ($3.87\;{\mu}g/cm^2$), eugenol ($3.92\;{\mu}g/cm^2$), and acetyl eugenol ($7.21\;{\mu}g/cm^2$). These results suggest that D. pteronyssinus may be controlled more effectively by the application of eugenol congeners than D. farinae. In comparison with synthetic acaricides, the acaricidal activities of eugenol, isoeugenol, methyl eugenol, and methyl isoeugenol were about 1.9-2.2 times more toxic than benzyl benzoate. Furthermore, the most toxic constituent against T. putrescentiae was exhibited on eugenol ($10.11\;{\mu}g/cm^2$), followed by methyl eugenol ($38.67\;{\mu}g/cm^2$) and acetyl eugenol ($70.09\;{\mu}g/cm^2$), but no activity was observed for isoeugenol and methyl isoeugenol. The results suggested that eugenol congeners may be useful as a new source for selective control of house dust mites and stored food mites.
