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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Conservation Ecology
GROWTH RATES OF CADDIS LARVAE USING NATIVE VS. NON-NATIVE LEAF LITTER.
D. Allbut, T. Chew, and T. Dudley. Department of Integrative Biology, University of California, Berkeley, California, USA 94720-3140
The leaf litter of two invasive riparian plants, giant reed (Arundo donax) and saltcedar (Tamarix parviflora) were compared with native alder and willow to determine suitability for detritivorous caddis larvae, Gumaga sp. and Lepidostoma sp. Leaf material was dried, conditioned for 3 weeks in a central California stream, then placed into laboratory containers (5 replicates for each litter treatment) with 20 early-instar larvae (insect species were tested at different times of year). Leaf material was replaced weekly, and after 6 weeks all larvae were dry-weighed. Gumaga growth on native litter was twice that on Arundo (0.035 vs. 0.015 mg dry weight), while Tamarix-fed larvae did not differ significantly (0.027 mg, p>0.05, ANOVA) from those provided with native litter. Lepidostoma showed a similar trend, but differences were not significant for this shredder. These results suggest that non-native plant litter was generally poorer for supporting insect growth. Furthermore, Gumaga, an FPOM feeder, benefited from detrital material that collected on the highly branched Tamarix litter; Arundo is a large grass, and the flat blade provided a less-suitable surface for FPOM deposition and insect utilization.
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