Evaluating the enemies hypothesis in a clover-cabbage intercrop: effects of generalist and specialist natural enemies on the turnip root fly (Delia floralis)
Evaluating the enemies hypothesis in a clover-cabbage intercrop: effects of generalist and specialist natural enemies on the turnip root fly (Delia floralis)
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DOI：
10.1111/j.1461-9563.2009.00452.x
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发表时间：
2010-05-01
影响因子：
1.6
通讯作者：
Ramert, Birgitta
中科院分区：
文献类型：
--
作者：
Bjorkman, Maria;Hamback, Peter A.;Ramert, Birgitta
研究了甘蓝-红三叶草间作系统中萝卜根蝇Deliafloris与甘蓝单一栽培相比资源集中假说和天敌假说的相对重要性。在两个生长季节的田间实验中测量了Deliafloris卵密度以及通才捕食者的活动密度。第二年，除了捕食者排除实验外，还进行了一项人工放置蛋的捕食研究，以估计该季节的捕食总量。寄生率是根据蛹样本估算的。这两年单一栽培中Deliafloris 的产卵量较多。捕食者活动密度在处理和研究年份之间有所不同。 Delia spp.、Bembidion spp. 的已知天敌。和 Aleochara bipustulata 对单一栽培中活动密度较高的栽培系统表现出强烈的反应。然而，这种反应似乎主要是由栖息地偏好引起的，而不是由花荠菜卵密度引起的。间作中花荠菜蛹数量的减少可能是由于三叶草的存在导致产卵行为的破坏，因为栽培系统之间的捕食率和寄生率都没有差异。
The relative importance of the resource concentration hypothesis and the enemies hypothesis was investigated for the turnip root fly Delia floralis in a cabbage-red clover intercropping system compared with a cabbage monoculture.Delia floralis egg densities were measured as well as the activity-densities of generalist predators in a field experiment during two growing seasons. In the second year, a study of egg predation with artificially placed eggs was conducted, in addition to a predator exclusion experiment, to estimate total predation during the season. Parasitization rates were estimated from samples of pupae.Delia floralis oviposition was greater in the monoculture during both years. The predator activity-densities differed between treatments and study years. The known natural enemies of Delia spp., Bembidion spp. and Aleochara bipustulata showed a strong response to a cultivation system with higher activity-densities in the monoculture. The response, however, appeared to be caused primarily by habitat preferences and not by D. floralis egg densities.The reduction in the number of D. floralis pupae in the intercropping may be explained by a disruption in oviposition behaviour caused by the presence of clover because neither predation, nor parasitization rates differed between cultivation systems.