Abundance, life cycle, production dynamics and trophic basis of a dominant caddisfly (Hydropsyche carbonaria McLachlan) in a subtropical stream in China

During the period of June 2003 to June 2004, we investigated the population dynamics, life cycle, and secondary production and its trophic basis of larvae of a dominant caddisfly Hydropsyche carbonaria McLachlan in a second order stream in the Hanjiang River basin of China. The caddisfly completed two generations in one year and attained its standing stock peaks in January and again in June. The annual secondary production (dry weight) and P/B ratio of the larva estimated by the size-frequency method, were 53.49g/m(2) and 9.8, respectively, and most of the production occurred in the winter. The main food types found in the foregut were animal materials and amorphous detritus, comprising of 40.5% and 38.3% of its ingestion, and contributing 64.4% and 23.5% to its production, respectively.