Evolution of architectural behavior in larval caddisflies (Trichoptera)

Recently inferred phylogenetic relationships among caddisfly families provide a revised understanding of the probable course of evolution for the various types of constructions undertaken by Trichoptera larvae. Based on a phylogeny of (Annulipalpia(Rhyacophiloidea(Glossosomatidae(Hydroptiloidea + Integripalpia)))), the ancestral Annulipalpia larva evolved retreat-building behavior and ceased spinning a cocoon for pupation. The larva of the sister lineage was free-living, constructing a dome-like pupation chamber just before spinning its semipermeable cocoon, as seen in Rhyacophiloidea. All instars of the ancestral larva of Glossosomatidae constructed a precocious pupation chamber for protection from predation while browsing on substrate biofilm. The ancestral larva of Hydroptiloidea delayed construction of its precocious pupation chamber until its final larval instar. Before pupation, the ancestral larva of Integripalpia sealed the ends of its tubular larval case with a silk mesh but did not spin a cocoon.