Aquatic vertebrate predation threats to the Platte River caddisfly (Trichoptera: Limnephilidae)

The Platte River caddisfly, Ironoquia plattensis Alexander & Whiles (Trichoptera: Limnephilidae), was once the most abundant component of the benthic macroinvertebrate community in Platte River backwater sloughs, attaining larval densities of approximately 1,000 individuals per m 2 and accounting for approximately 40% of the emerging secondary production. Surveys for the species conducted between 1999 and 2004 found 6 sites with I. plattensis, and recent sampling has found 29 additional sites with the caddisfly; however, only one population has densities comparable to those found at the type locality. Backwater sloughs where I. plattensis occur provide habitat for a variety of aquatic vertebrates which could potentially threaten the species’ persistence. This project tested the ability of seven fish species and a tadpole to consume I. plattensis larvae. Replicated experiments presented vertebrates with 3 early instar I. plattensis larvae in 9.5 liter aquaria. Based on Kruskal-Wallis one-way ANOVA (P = 0.05), significant predation was observed only with brook stickleback, Culaea inconstans Kirtland (Gasterosteiformes: Gasterosteidae), feeding trials. C. inconstans consumed a mean of 0.49 I. plattensis larvae per 24 h. Our results suggest I. plattensis populations may be reduced by the presence of brook stickleback in backwater sloughs. Alterations to the Platte River may increase the chances for I. plattensis and C. inconstans habitat overlap from greater river connectivity.