The relationship of microhabitat conditions and the distribution of three dipteran larvae within the leaves of the northern pitcher plant (Sarracenia purpurea).

Abstract

The study of consumer dynamics and the effect of abiotic factors on consumer interactions is important for understanding community dynamics. This investigation examined the relationships of the flesh fly Blaesoxipha fletcheri, the mosquito Wyeomyia smithii, and the midge Metriocnemus knabi living within the northern pitcher plant Sarracenia purpurea and the effect of fluid pH and fluid volume on their densities and interactions. The fluid contents were collected from young pitcher plant leaves in the field, and the larval inhabitats were counted, measured, and their associations with each other noted. Since the density of W. smithii increased, its average length decreased, W. smithii experienced intraspecific competition. The density of M. knabi decreased in the presence of W. smithii, so M. knabi was negatively affected by interspecific competition. No evidence was found to support the presence of commensalism between W. smithii and M. knabi. Both W. smithii and M. knabi positively correlated with fluid volume. pH correlated positively with M. knabi alone and negatively with M. knabi in the presence of W. smithii. Many factors, including internal, external, microhabitat, and macrohabitat scales, affect community dynamics and, however difficult, must be considered in order to acquire a complete and accurate picture of the system.