天敌竹盲走螨在纯竹林中种群数量锐减的原因研究

The cause of the decrease of population dynamic of Typhlodromus bambusae Ehara in moso bamboo forest

本项研究针对我国南方毛竹林 ,近年害螨突发性成灾的现象 ,进行调查与研究 ,结果表明 :纯竹林害螨总量平均高于混交林 2 89.2 8% ,混交林天敌竹盲走螨 (Typhlodromus bambusae Ehara)总量平均高于纯竹林2 6 3.5 6 % ;混交林益、害螨比例为 1∶ 13,而纯竹林益、害螨比例是 1∶ 118。研究表明纯竹林地面垦复、劈草 ,使得以芒草为生的芒草裂爪螨 (Schizotetranychus miscanthi Saito)种群数量急剧下降 ,导致乡土优势种竹盲走螨缺乏中间食物 ,难以维持种群。在毛竹——芒草混生的毛竹林 (含其它树种 )由于毛竹上害螨和林下芒草裂爪螨受到共同天敌——竹盲走螨的控制维持着稳定的益、害种群数量 ,虽然有害螨 ,但不成灾 ,在纯竹林由于地面垦复、劈草破坏原有已形成的生物链 ,导致毛竹害螨失去天敌控制而突发性成灾 ,证明纯竹林中天敌锐减是导致毛竹害螨暴发成灾的重要因素。

This paper dealt with the studies on outbreaks phenomenon of pest mites of moso bamboo (Phyllostaychs pubescens) forests in south of China. The result showed that the total pest mites in monoculture forests was on an average 289.29% as high as that in polyculture stands. Thphlodromus bambusae Ehara, a natural enemy, in the polyculture forests was on an average 262.5% as high as that in the monoculture. The proportion of pest mites and nature enemy in the monoculture forests was on an average 1∶118,but in the polyculture was on an average 1∶13. The result from these research showed that the outbreaks of pest mites in bamboo forests was caused by fatal disruption of the stable interaction between predators and their 3 prey species in the fields through farming activity such as removal of the plants under bamboo forests. For example, the population of Schizotetranycus nanjingensis Ma & Yuan had been regulated by T. bambusae, where another spider mite species S. miscanthi Saito in the host plant (Miscanthus sp.) is very important prey species for keeping the population of T. bambusae. Monoculture may reduce the abundance of natural enemies of phytophagous mites by reducing alternative habitats and food for them, which indirectly contribute to the outbreake of pest mites on bamboo in Fujian Province.