论短期农作物生境中节肢动物群落的重建Ⅲ.群落重建与天敌保护利用

The reestablishment of the arthropod community in short-term crop fields:Ⅲ. Community reestablishment and conservation and utilization of natural enemies

保护利用天敌是农田害虫生物防治的基本手段。短期农作物生境中的天敌亚群落周期性地呈现出群落重建、群落发展和群落瓦解 3个阶段。其中的重建阶段对抑制害虫的发生和危害至关重要。天敌亚群落的重建与其种库、群落本身和作物生态系统之间的相互作用关系 ,是群落水平上保护利用天敌的理论基础之一。因此 ,可以指导自然天敌的保护和持续利用 。

Conservation and utilization of natural enemies is the basic measure in biological control of agricultural pests. The enemy sub\|community in short\|term crop fields appears periodically 3 different stages that are called community reestablishment, community development and community collapse. \;Pests usually cause damage to a crop 1~2 generations after their first occurrence in the field. During that period, enemy sub\|community that is still under reestablishment is crucial to control the pests. If pests are successfully controlled with natural enemies during that period, they won't cause obvious damage to the crop. Otherwise, serious damage may come out. Therefore, enemy sub\|community during reestablishment stage is particular important in suppressing pest abundance and damage. In other words, the role of enemy sub\|community before pests' outbreak should be emphasized.\;Due to periodical transplanting and harvest of short\|term crops, enemy sub\|community inhabits alternately in crop field and in non\|crop habitats. Non\|crop habitats act as species pool of the enemies in the crop field and are important for the reestablishment of the enemy sub\|community in the crop field. In addition, the sub\|community itself and the crop ecosystem are also of importance. Better understanding of the interaction between reestablishment of enemy sub\|community, its species pool, and the crop ecosystem, better and more measures for promoting reestablishment of the sub\|community. \;Natural enemies are usually manipulated at 3 levels——enemy sub\|community, its species pool and crop ecosystem. The measures aim at enhancement of enemies' efficacy through achieving a more abundant, more diversified, or faster reestablished enemy sub\|community. In fact, those measures and their effects can be interpreted by the interaction between reestablishment of enemy sub\|community, its species pool, and the crop ecosystem. Therefore, at community level, this interaction is an important aspect of the theoretical basis for conservation and utilization of natural enemies. It is helpful to promote biological pest control in short\|term crop ecosystems.\;Some measures increase enemies' abundance, some increase enemies' diversity. Relative importance of abundance and diversity of enemy sub\|community is still unknown. In order to identify and implement specific measures in the field, we need to understand the relative importance.