Insecticidal Mechanism of Wintergreen Oil Against the Health Pest Paederus fuscipes (Coleoptera: Staphylinidae).

Paederus fuscipes, a health pest, causes dermatitis linearis in humans. Wintergreen oil exhibits optimal insecticidal activity against P. fuscipes. However, the insecticidal mechanism remains unclear not only in P. fuscipes but also in other pests. In this study, we explored the insecticidal mechanism of wintergreen oil in terms of its effect on the activity of acetylcholinesterase (AChE) enzyme and detoxifying enzymes (carboxylesterase, glutathione-S-transferase, and mixed function oxidase); such effect was studied by fumigation both in vivo and in vitro in P. fuscipes male and female adults. In the in vivo and in vitro experiments on male and female adults, wintergreen oil did not significantly affect the activities of the three detoxifying enzymes. Hence, the mode of action of wintergreen oil may be unrelated to the three detoxifying enzymes. Wintergreen oil significantly inhibited AChE activity. When wintergreen oil was tested at different times in vivo, the highest inhibition rates were 41.99% (male) and 40.91% (female). When different doses of wintergreen oil were used for in vivo treatment, the highest inhibition rates were 33.78% (male) and 43.33% (female). When wintergreen oil was tested in vitro, the highest inhibition rates were 31.06% (male) and 35.57% (female). In vitro with chlorpyrifos as a positive control, the AChE activity of 3-μl wintergreen oil treatment was significantly lower than that of 10 mg/liter chlorpyrifos in both P. fuscipes male and female adults. The results demonstrated that AChE is a potential key factor, maybe a target enzyme, in the mechanism of wintergreen oil against P. fuscipes.