Müller C B, Godfray H C J
Department of Biology and NERC Centre for Population Biology, Imperial College at Silwood Park, Ascot, Berkshire, SL5 7PY, UK e-mail:
Oecologia. 1999 Apr;119(1):120-125. doi: 10.1007/s004420050767.
We investigated why two species of aphids (Aphis jacobaeae and Brachycaudus cardui) were very rare in a study site despite their abundance in the surrounding area. The study site contained many common species of aphid and we tested the hypothesis that the community of aphid predators in the field excluded the missing species. Colonies of the two aphid species were artificially initiated in the experimental site and allocated to one of four treatments: control; ground predator exclusion; total predator exclusion, and provision of mutualist ants. Two measures of colony performance were analysed: longevity and cumulative aphid density. Colonies decline naturally in late summer but control colonies disappeared very quickly while colonies protected from all predators survived the longest. The performance of colonies protected from just ground predators was intermediate. We failed to persuade ants to tend A. jacobaeae. Colonies of B. cardui attended by ants performed better than controls and those with ground predators excluded, but not as well as those with all predators excluded. We conclude that the absence of the two species of aphid in the study site is influenced by the resident predator community, and by the availability of mutualists.
我们研究了为何两种蚜虫（千里光蚜和卡氏短尾蚜）在某研究地点极为稀少，尽管它们在周边地区数量众多。该研究地点有许多常见的蚜虫种类，我们检验了这样一个假设：田间的蚜虫捕食者群落排除了这些缺失的物种。在实验地点人工建立了这两种蚜虫的群体，并将其分配到四种处理方式之一：对照；地面捕食者排除；全部捕食者排除，以及引入共生蚂蚁。分析了群体表现的两个指标：寿命和蚜虫累积密度。夏末时群体自然衰退，但对照群体很快消失，而免受所有捕食者侵害的群体存活时间最长。仅免受地面捕食者侵害的群体表现处于中间水平。我们未能说服蚂蚁照料千里光蚜。有蚂蚁照料的卡氏短尾蚜群体比对照群体以及排除了地面捕食者的群体表现更好，但不如排除了所有捕食者的群体。我们得出结论，研究地点这两种蚜虫的缺失受当地捕食者群落以及共生者可利用性的影响。
