The relationship between Wyeomyia smithii and Metriocnemus knabi larvae and the insectivorous plant, Sarracenia purpurea.

Abstract

Species coexistence may lead to specialized interactions. The abundance or limitation of resources may be an integral factor in determining which adaptations species evolve. The relationship between the pitcher plant, Sarracenia purpurea, and the larvae, Wyeomyia smithii and Metriocnemus knabi, that inhabit its water-filled pitcher, was investigated. Because the environment S. purpurea inhabits is nitrogen poor, nitrogen was assumed to be an indicator of plant fitness. The relationship between the larvae and the plant was determined by examining the correlation between larval biomass, detrital biomass, the total amount of solid nitrogen in the detritus, and the total amount of soluble nitrogen in pitcher water. There was no significant correlation among these variables. Thus, the relationship between S. purpurea and the two insect species was found to be neither nutualistic nor parasitic but commensal, and to have no direct correlation with plant fitness as measured by available nitrogen.