Maternal behaviours may explain riffle-scale variations in some stream insect populations

Abstract

Species composition and abundance of larval insects can vary significantly between similar channel units (riffles) on the same stream as well as between similar streams. The source of this variation is largely unexplained, but important because such spatial variations can influence population and community dynamics and the design of sampling programmes. The maternal and oviposition behaviours of some aquatic insects are specialised, such that eggs are laid in particular locations, and this could influence the spatial distribution of eggs and larvae within a stream. In a relatively short length of stream (1 km), we tested whether the number of oviposition sites influenced the number of larvae..