Aspen Bibliography

Effects of fungal mycelia and enzymatically degraded leaves on feeding and performance of caddisfly (Trichoptera) larvae

Document Type

Article

Journal/Book Title/Conference

Journal of the North American Benthological Society

Volume

7

Issue

3

First Page

205

Last Page

211

Publication Date

1988

Abstract

We altered patterns of fungal growth, extracellular enzyme production, and degradation of aspen leaves by adding glucose to cultures. When glucose was present, fungi formed a thick mat of mycelium on the surface of leaves and caused a net increase in mass of leaves. In glucose-containing cultures, activities of pectin lyase, polygalacturonase, and endoglucanase were greatly reduced, and leaves were not softened. We also grew the same fungi on leaves in the absence of glucose for incubation times that produce high fungal activity and palatability for caddisfly larvae (i.e., leaves were fully conditioned). In these cultures, fungi produced high enzymatic activities and caused mass loss and softening of leaves. When offered a choice between leaves colonized by the same fungus in the presence or absence of glucose, caddisfly larvae ingested greater amounts of material (mainly fungal mycelia) from leaves colonized in the presence of glucose. Growth rates of larvae fed leaves colonized in the presence of glucose were not significantly different from those fed fully conditioned leaves. However, when larvae fed on leaves from glucose-containing cultures, consumption rates were less than half and ingestion conversion efficiencies were more than double those of larvae fed leaves from glucose-free cultures of the same fungus. We conclude that fungal mycelia played a greater role in determining food selection by caddisfly larvae and were a better food source than the combination of extracellular enzymes, modified leaf tissue, and mycelia associated with leaves that had been fully conditioned by the same fungus.

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