Abstract: Celangulin Ⅴ isolated from the root bark of Celastrus angulatus Max. is a new kind of insecticidal compound. The effects of celangulin Ⅴ on the muscle cells of Mythimna separata were determined with electron microscopy observation. It was found that celangulin Ⅴ had a myotoxic effect on the adult flight muscles and larval skeletal muscles of M.separata. The sarcolemma and inner membrane were disrupted and mitochondria became wollen,vacuolated and disintegrated. The space between myofibrils and mitochondria significantly increased, the sarcoplasmic reticulum spread and pith tissue occurred, the nucleus became swollen, nucleoplasm concentrated and the nuclear membrane disrupted, the space around trachea enlarged and sarcomeres contracted abruptly. These results suggest that the sarcolemma and inner membrane might be the target acted on by celangulin Ⅴ.

Key words: celangulin Ⅴ, Mythimna separata, myotoxicity