LIFE CYCLE, GROWTH, SURVIVAL, AND PRODUCTION OF MACRONYCHUS GLABRATUS (COLEOPTERA, ELMIDAE) IN NORTHWEST ARKANSAS AND SOUTHEAST TEXAS STREAMS

摘要

The goal of this study was to better understand the ecology of Macronychus glabratus, a xylophagous aquatic beetle that plays an important role in the conditioning and breakdown of submerged woody debris. In the Illinois and White Rivers of northwest Arkansas, and Harmon Creek in southeast Texas, M. glabratus produced six larval instars. Primary recruitment in Arkansas was during March and April, but first instar larvae were also collected during February and May. Primary recruitment in Texas was during February and March, but first instar larvae were also collected during January and April. Adults made up similar to 10-20% of the population throughout the year in both Arkansas and Texas, indicating that adults are probably long lived. In the laboratory, sixth-instar larvae pupated above the water line in a hollowed oval space beneath bark or in rotted wood. Emergence began similar to 18 days later. After emergence adults crawled back the water. In the laboratory, adults oviposited and first-instar larvae began to hatch after 22 days. Production of M. glabratus in Arkansas was 1.65 g/m(2)/yr, standing stock biomass was 0.48 g/m(2), and the P/B ratio was 3.46. In Texas, production was 0.51 g/m(2)/yr, standing stock biomass was 0.19 g/m(2), and the P/B ratio was 2.63. [References: 31]