Effects of Celangulin IV and V From Celastrus angulatus Maxim on Na+/K+-ATPase Activities of the Oriental Armyworm (Lepidoptera: Noctuidae)

Na+/K+-ATPase (sodium pump) is an important target for the development of botanical pesticide as it is responsible for transforming chemical energy in ATP to osmotic work and maintaining electrochemical Na+ and K+ gradients across the cell membrane of most animal cells. Celangulin IV (C-IV) and V (C-V), which are isolated from the root bark of Celastrus angulatus, are the major active ingredients of this insecticidal plant. The activities of C-IV and C-V on Na+/K+-ATPase were investigated by ultramicro measuring method to evaluate the effects of C-IV and C-V on Na+/K+-ATPase activities of the brain from the fifth Mythimna separata larvae and to discuss the insecticidal mechanism of C-IV and C-V. Results indicate that inhibitory activities of Na+/K+-ATPase by C-IV and C-V possess an obvious concentration-dependent in vitro. Compared with C-IV, the inhibition of C-V on Na+/K+-ATPase was not striking. In vivo, at a concentration of 25 mg/liter, the inhibition ratio of C-IV on Na+/K+-ATPase activity from the brain in narcosis and recovery period was more remarkable than that of C-V. Furthermore, the insects were fed with different mixture ratios of C-IV and C-V. The inhibition extent of Na+/K+-ATPase activity was corresponded with the dose of C-IV. However, C-V had no notable effects. This finding may mean that the mechanism of action of C-IV and C-V on Na+/K+-ATPase were different. Na+/K+-ATPase may be an action target of C-IV and C-V.