Results of two field experiments showed that selective removal of omnivorous mosquito larvae (Aedes triseriatus (Say)) functioning as top predators in the food web of a temperate, tree hole ecosystem resulted rapidly in increased abundance of flagellate and then ciliate populations. Flagellate density increased from <1 per ml to >10³ per ml within 4 days of omnivore removal, followed shortly thereafter by an increase in ciliate density from <1 per ml to >10² per ml, after which flagellate density declined, and flagellate and ciliate densities stabilized. Rod-shaped bacteria increased slightly in density after removal of larval mosquitoes, then declined as protist density increased. Cocciform bacteria did not vary in density with these changes, thus the trophic cascade dampened at the remotest trophic level. Concomitant with the increase in protist densities, some bacteria formed elongated filaments >10 µm in length, likely an anti-predation, morphological response stimulated by suddenly intensified grazing as protozoan density rose. Results suggest that feeding by omnivorous mosquito larvae exhibited strong top-down effects on flagellate and ciliate populations, depressing them to below their equilibrium densities and nearly to extinction in tree hole ecosystems.

中文翻译：

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在去除杂食性蚊子幼虫后，树洞生态系统中微生物之间的急性营养级联反应。

两个现场实验的结果表明，选择性去除作为温带树洞生态系统食物网中顶级捕食者的杂食性蚊子幼虫（Aedes triseriatus (Say)）会迅速增加鞭毛虫和纤毛虫种群的丰度。在去除杂食动物的 4 天内，鞭毛虫密度从 <1/ml 增加到 >10 ³ /ml，随后不久纤毛虫密度从 <1/ml 增加到 >10 ²每毫升，之后鞭毛虫密度下降，鞭毛虫和纤毛虫密度趋于稳定。去除幼虫蚊子后，杆状细菌的密度略有增加，然后随着原生生物密度的增加而下降。球状细菌的密度没有随着这些变化而变化，因此营养级联在最远的营养级受到抑制。随着原生生物密度的增加，一些细菌形成了长度大于 10 µm 的细丝，这可能是一种抗捕食的形态反应，随着原生动物密度的增加，突然加剧的放牧刺激了这种反应。结果表明，杂食性蚊子幼虫的摄食对鞭毛虫和纤毛虫种群表现出强烈的自上而下的影响，将它们压低至平衡密度以下，并在树洞生态系统中几乎灭绝。