Acaricidal activity of constituents derived from peppermint oil against Tyrophagus putrescentiae.

The acaricidal activities of peppermint oil and menthol isomers against mites in stored food were evaluated using fumigant and contact bioassays and were compared with the activity of benzyl benzoate as a synthetic acaricide. Based on the 50% lethal dose (LD50) values against Tyrophagus putrescentiae in the fumigant bioassay, menthol (0.96 μg/cm(2)) was approximately 12.18 times more effective than benzyl benzoate (11.70 μg/cm(2)), followed by (+)-neomenthol (1.33 μg/cm(2)), (-)-menthol (1.60 μg/cm(2)), and (+)-menthol (1.90 μg/cm(2)). In the filter paper bioassay, menthol (0.55 μg/cm(2)) was about 15.18 times more active than benzyl benzoate (8.35 μg/cm(2)), followed by (-)-menthol (0.84 μg/cm(2)), (+)-menthol (0.92 μg/cm(2)), and (+)-neomenthol (1.72 μg/cm(2)). However, (+)-isomenthol did not exhibit any acaricidal activity against T. putrescentiae in the fumigant and filter paper bioassays. These results indicate that peppermint oil and menthol isomers could be effective natural acaricides for managing mites in stored food.