The possibility of sustainable pest management by introducing bio-diversity : simulations of pest mite outbreak and regulation

摘要

Since the late 1980s, spider mite pests have caused serious damage to many moso bamboo (Phyllostachys pubescens) forests in China's Fujian province. The culms of this plant are an essential component of the building and handicraft industries, and its shoots are a prized food item in many Asian countries. Furthermore, bamboo forests play an important soil conservation role in mountainous areas. We examined the pest mite outbreaks in several Fujian moso bamboo plantations, and could show that a change in cultivation style from polyculture (a kind of mixed forest) to monoculture was the prime reason for the outbreaks. We then tried to identify factors that resulted from such a cultivation change. Using a systems simulation approach, we determined that systems consisting of one common predator, two host-specific pest mites on different host plants frequently became stable when the pest mites were at low density, meaning that at least two plants, moso bamboo and Chinese silvergrass are necessary to maintain stable predator-prey interactions in moso forests. This finding clearly indicates that bio-diversity, even when it consists of only 2 plants and 3 mite species as in this study, is necessary for the sustainable regulation of large-scale forests, such as moso bamboo plantations.