蜜源植物波斯菊对捕食性天敌种群动态的影响

蜜源植物有利于天敌昆虫田间定殖与增效控害，是保护性生物防治的重要组成部分。为筛选及评价蜜源植物对天敌的涵养作用，本研究比较了波斯菊Cosmos bipinnata、千屈菜Lythrum salicaria、荷兰菊Symphyotrichum novi-belgii与对照杂草区域的天敌、害虫种群动态，同时评价了不同种植密度下波斯菊对瓢虫及蚜虫种群数量影响。结果表明：与对照杂草区域相比，千屈菜区域内天敌及害虫数量均显著较多，波斯菊区域内天敌数量显著较高但害虫数量较少，优势天敌为捕食性瓢虫。不同种植密度下波斯菊花带内的捕食性瓢虫和蚜虫数量存在显著差异；种植密度为50%波斯菊花带内瓢虫和蚜虫数量高于种植密度100%，且两种密度下波斯菊花带内益害比均显著高于对照杂草区域。本研究初步表征：波斯菊花带对捕食性天敌具有较好的诱集涵养作用，可作为天敌优良的蜜源植物增效害虫生物防治。

Effect of Nectar Plant Cosmos bipinnata on the Population Dynamics of Predatory Natural Enemies

Nectar plant, an important part of conservation biological control, can support the colonization of natural enemies in filed and enhance pest biological control. In order to evaluate the effect of nectar plants on natural enemies, population dynamics of natural enemies and pests in Cosmos bipinnata, Lythrum salicaria, Symphyotrichum novi-belgii strips were compared with those in the natural weed area, and the impact of cosmos on ladybird and aphid populations were evaluated under different planting densities. Results showed that, in comparison with the natural weed area, the population size of natural enemies and pests in L. salicaria was higher, and the population size of natural enemies in cosmos strip was higher while that of the pests was less, where the predatory ladybirds were the dominant natural enemies. The population size of ladybirds and aphids in cosmos differed significantly between planting densities, higher in cosmos strip with 50% planting density than that with 100% planting density, and the ratio of natural enemies to pests was significantly higher in cosmos strips of the two planting densities than that of the natural weed area. This study indicates that cosmos strip attracts and conserves natural enemies in filed and can be potentially used as nectar plants in habitat management for conservation biological control.