荔枝-旋扭山绿豆复合种植系统对荔枝害虫的生态调控作用

对营建荔枝 旋扭山绿豆复合种植系统和荔枝单一种植系统的昆虫群落结构及动态进行系统调查.结果表明，复合种植园中荔枝害虫总数显著减少，仅为单一种植园的61.27%，在果实生长关键期的5月份的数量仅是单一种植园的50.45%.旋扭山绿豆与荔枝树存在相互协调关系：两者具较少共同害虫，其害虫却存在多种共同天敌；旋扭山绿豆冬季开花为天敌昆虫越冬提供庇护场所和替代食物，两者花期基本衔接，利于害虫天敌的生存及繁殖.在荔枝开花和荔果生长期的3～6月份，复合园荔枝树上的天敌数量与害虫数量之比分别为单一园的4.22、2.34、2.28和20.63倍，有效地发挥了对荔枝害虫的控制作用.

Ecological control effects of Litchi chinensis-Desmodium intortum complex plant ecosystem on litchi pests

An investigation on the community structure and dynamics of litchi pests and their natural enemies in constructed Litchi chinensis-Desmodium intortum complex plant ecosystem and single L.chinensis ecosystem showed that the total amount of litchi pests in the complex plant ecosystem was 61.27% of that in the single ecosystem in whole year,and only 50.45% in May,the key time for fruit development,which suggested that there was an interaction between D.intortum and L.chinensis.D.intortum and L.chinensis had a few common pests,but many common natural enemies.D.intortum florescence in winter provided shelter and substitutive food for the natural enemies of pests to survive in the extreme environmental conditions in winter.L.chinensis florescence was on the heel of D.intortum florescence,which provided better conditions for the natural enemies to survive and multiply.During florescence and fruit development stages of L.chinensis(from March to June),the predator/prey ratio in complex plant system was 4.22,2.34,2.2 and 20.63 times of that in single plant system in March,April,May and June,respectively,indicating the good control effect on pests of L.chinensis.