The diet and growth of a leaf-shredding caddisfly, Pycnopsyche, in streams of contrasting disturbance histories

This study investigated the diet and growth of a leaf-eating caddisfly, Pycnopsyche, in streams draining a >60 year-old reference forest and a 16-year-old c1earcut (disturbed) forest at Coweeta Hydrologic Laboratory in southwestern North Carolina. The objective was to examine whether Pycnopsyche larvae grew better on fast-decaying leaf types more prevalent in the disturbed streams (e.g., black birch) because leaf-eating insects (shredders) in a previous study were more productive in these streams despite having less food available. Larvae consumed mostly unidentified plant material in streams of both forest types over three seasons (fall, winter, and spring) which suggested larvae did not consume higher quality foods (e.g., algae) in disturbed streams. When fed 2-mo "conditioned" black birch and white oak leaves, lab experiment larvae grew significantly faster on birch leaves. However, when larvae were fed the same leaf types after 3 mo of conditioning, larvae grew significantly faster on oak leaves. A field growth experiment conducted for 42 d using leaf diets representative of both forest types and conditioned for 2 mo found Pycnopsyche grew better on the diet representative of the reference forest. found Pycnopsyche grew better on the diet representative of the reference forest.