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Presented at the NABS Annual meeting, Vancouver, British Columbia, 2004
in Wetlands and Lentic Ecology
Caddisfly life history and physiological adaptations for survival in temporary wetlands
M.L. Mumford1 and S.A. Wissinger1. 1Biology Department, Allegheny College, Meadville, PA 16335 USA, 2.
We studied the life history and ecology of two species of caddisflies, Limnephilus indivisus (Limnephilidae) and Ptilostomis ocellifera (Phryganeidae) that inhabit temporary wetlands in northeastern North America. Adults emerge in spring, but egg masses do not appear until autumn, suggesting adult diapause during summer when larval habitats are dry. Field observations and substrate manipulations revealed that egg masses are always deposited within the margins of temporary basins, but not below the water line. We manipulated immersion time in the laboratory and found that embryology can be completed in the egg masses without immersion, but larvae only emerge after inundation. Larval habitats are vulnerable to subsequent drying and we found that larvae can tolerate desiccation for two weeks in experimental microcosms. Although larvae remain active in winter, shallow areas of their habitat freeze into the substrate, and we compared the tolerance of the two species to experimental freezing. Our results provide detailed information about the life history and physiological adaptations that allow these caddisflies to exploit temporary wetlands including 1) adult diapause when habitats are dry, 2) deposition of desiccation-tolerant eggs masses in dried, 3) delayed larval emergence upon inundation, and 4) short-term desiccation and freeze tolerance in larvae.
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