Inhibition of Na+,K+-ATPase in Housefly (Musca domestica L.) by Terpinen- 4-ol and Its Ester Derivatives

To reveal the insecticidal mechanism of terpinen-4-ol, the activity of Na+,K+-ATPase in insects tested were determined in vivo and in vitro. The results showed that terpinen-4-ol and its ester derivatives had strong contact activity to housefly and the contact toxicities of its derivatives except Z3 were all superior or equivalent to terpinen-4-ol. All the 7 compounds had strong inhibition towards activity of Na+,K+-ATPase. With poisoning symptom exacerbating, the inhibition rates were gradually increased. In vitro, the IC50 of terpinen-4-ol, Z1, Z2, Z4, Z5, and Z6 was 155.89, 197.98, 96.02, 121.36, 124.85, and 153.74 μg mL−1, respectively. There was well correlation between the LD50 of terpinen-4-ol derivatives to housefly and the IC50 of terpinen-4-ol derivatives to Na+,K+-ATPase in housefly. In conclusion, Na+,K+-ATPase was likely the target of terpinen-4-ol against insects.