Lounibos L P, Escher R L, Nishimura N, Juliano S A
University of Florida, Florida Medical Entomology Laboratory, 200 9th St SE, Vero Beach, FL 32962, USA Fax: 561-778-7205; e-mail:
Department of Biological Sciences, Ecology Group, Illinois State University, Normal, IL 61790, USA, , , , , , US.
Oecologia. 1997 Jul;111(2):189-200. doi: 10.1007/s004420050225.
We identified, staged and counted the immature stages of mosquitoes from 1,826 censuses (with replacement) of the aquatic contents of ten treeholes surveyed every 2 weeks between 1978 and 1993. These time series were used to examine the population dynamics and effect on prey of the predatory mosquito Toxorhynchites rutilus. The mean annual frequency of occurrence of T. rutilus ranged from 0.02 to 0.67 among holes, and no fourth instars were recovered during a 30-month dry period. Oviposition and pupation by this species were recorded in all months, but most commonly in the spring. Overwintering larvae of the predator increased in weight during the prolonged fourth instar that preceded pupation in the spring. Time series analyses showed that the presence of a fourth instar T. rutilus significantly reduced the abundances of late-stage Aedes triseriatus mosquitoes. Pupal numbers of this prey species were more negatively affected by T. rutilus than were numbers of fourth instar A. triseriatus. Long-term declines in mean annual abundance of A. triseriatus prey during 16 years of observations on two holes were not correlated with increases in the mean annual frequencies of T. rutilus. Local extinctions of the aquatic stages of A. triseriatus within treeholes were common, but in most holes not significantly associated with the presence of T. rutilus, suggesting that predation does not routinely drive mosquito prey locally extinct in this ecosystem. The decoupling of T. rutilus and A. triseriatus, as revealed through these complete and long-term censuses, is contrasted with other reports of generalist predators causing extinctions of mosquito prey. Discrepancies among reported outcomes probably result from differences in duration of sampling periods and statistical procedures along with real differences in the intensity of predation among systems and sites.
我们对1978年至1993年期间每两周调查一次的十个树洞中的水生生物进行了1826次（有放回）普查，以识别、分期并计数蚊子的未成熟阶段。这些时间序列用于研究捕食性蚊子华丽巨蚊的种群动态及其对猎物的影响。华丽巨蚊在树洞中的年平均出现频率在0.02至0.67之间，在30个月的干旱期内未发现四龄幼虫。该物种在所有月份都有产卵和化蛹记录，但最常见于春季。捕食者的越冬幼虫在春季化蛹前的延长四龄期内体重增加。时间序列分析表明，四龄华丽巨蚊的存在显著降低了晚期三带喙库蚊的丰度。与四龄三带喙库蚊的数量相比，该猎物物种的蛹数量受华丽巨蚊的负面影响更大。在对两个树洞进行的16年观测中，三带喙库蚊猎物的年平均丰度长期下降与华丽巨蚊年平均出现频率的增加无关。三带喙库蚊在树洞中的水生阶段局部灭绝很常见，但在大多数树洞中，这与华丽巨蚊的存在没有显著关联，这表明在这个生态系统中，捕食通常不会导致蚊子猎物局部灭绝。通过这些完整且长期的普查所揭示的华丽巨蚊和三带喙库蚊之间的解耦，与其他关于广食性捕食者导致蚊子猎物灭绝的报道形成了对比。报告结果之间的差异可能是由于采样期持续时间和统计程序的不同，以及不同系统和地点捕食强度的实际差异。
