Temperature Influences on Adult Size, Development, and Reproductive Potential of Aquatic Diptera

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Abstract
Elevated temperature (2.5 and 4.0 °C) resulted in smaller body size of stream Diptera in outdoor experimental channels, and this trend applied to both predator and detritivore trophic groups. Comparison of cumulative emergence curves using the Kolmogorov–Smirnov test showed that most species developed more quickly in the heated channels; this led to greater overall survivorship. Reproductive potential, estimated from ovary area, did not change with body size for Conchapelopia aleta, Polypedilum aviceps, and Stempellinella brevis, and did so only weakly for Parametriocnemus lundbecki. In addition, females decreased in size more than males in the heated channels. Somatic growth appeared to be sacrificed to maintain reproductive potential, although loss of energy reserves could reduce the length of the reproductive stage. In balance, the aquatic Diptera demonstrated resistance to thermal elevation in the summer, even though ambient temperatures approached 30 °C. This may partially account for the group's ability to grow and develop throughout the year in extremely varied temperate environments.