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The multivoltine life history of Cheumatopsyche brevilineata (Iwata, 1927) (Trichoptera: Hydropsychidae), with a new method to estimate the population size of generations

Mochizuki, Shoko, Kayaba, Yuichi, Tanida, Kazumi
Aquatic insects 2014 v.36 no.2 pp. 135-147
Hydropsychidae, heat sums, instars, larvae, multivoltine habit, overwintering, population size, seasonal variation, surveys, water temperature
Cheumatopsyche brevilineata (Iwata, 1927) is a filter-feeding caddisfly without distinct separable generations. We conducted a life history survey of C. brevilineata under a natural thermal regime. This caddis species had a multivoltine life history and their generations partially overlapped each other. From the seasonal change of larval and pupal density, we recognized one overwintering generation and three non-winter generations. We propose a new method to estimate the population size of fourth instar larvae from each generation by using the ‘development zero’ and ‘effective degree-days’ methods. The second non-winter generation, developing under the hottest water temperature regime, had the largest population size and highest observed density. The overwintering generation, which developed under the coolest thermal regime, showed the smallest population size but its observed density was not the smallest.