Acaricidal Mechanism of Stellera chamaejasme Extracts Against Tetranychus cinnabarinus at Subcellular Level

The extracts of S. chamaejasme were reported to have strongly acaricidal activity against T. cinnabarinus, but the mode of its action against mites is unclear. In this study, the effects on T. cinnabarinus caused at subcellular level by S. chamaejasme extracts were evaluated by transmission electron microscopy. Exposure to S. chamaejasme extracts, bilayer membrane detached and nuclear condensed. The crista of mitochondria, the stacking of Golgi cisternae, and endoplasmic reticulum became disintegrated partly. The arrangements of the muscle cells also became irregular and loose. The above-mentioned subcellular structure change of T. cinnabarinus may be signs of dysfunction of the nervous system, digestive system, and so on. The changes of the activity of the priority target enzyme of the insecticides-glutathione peroxidase (GSH-Px). GSH-Px activity was greatly enhanced since 18th hr post-treatment as a consequence of exposure to S. chamaejasme extracts and greatly promote the detoxification system of T. cinnabarinus.