Biology and larval feeding habits of coexisting hydroptilidae (Trichoptera) from a small woodland stream in northeastern Ohio

Hydroptila consimilis Mosely, Ochrotrichia spinosa (Ross), and O. wojcickyi Blickle exhibited a close association with the appearance of the filamento us chlorophyte Cladophora (April to June) in a small woodland stream in nor theastern Ohio. Laboratory rearings showed that these microcaddisflies disp layed similar life cycles and exhibited hypermetamorphosis. H. consimilis m andibles are specialized for piercing individual cells within filaments of Cladophora to facilitate removal of cellular contents, whereas Ochrotrichia spp. have robustly cusped mandibles suited for piercing Cladophora and scr aping diatoms from benthic substrates. Proportional similarity, analysis of videotaped behavior illustrated that the feeding habits of third-instar Oc hrotrichia exhibited a low similarity (0.44) to the other instars tested (O chrotrichia fifth and Hydroptila first, third, and fifth) because of their frequent consumption of diatoms (17% of feeding efforts); all other instars tested. were highly similar to each other (0.72- 0.86). This division of t rophic resources (i.e., differential use of diatoms versus Cladophora) mini mized niche overlap between the two genera. All instars of H. consimilis an d Ochrotrichia spp. fed, heavily on the apical (therefore the smallest) cel ls of Cladophora filaments, and the time required to consume cells decrease d significantly as larvae matured (P < 0.05). Larval Hydroptilidae are well adapted morphologically and behaviorally to consume Cladophora, anti these algal filaments appear to represent a heterogeneous food source just as te rrestrial host plants are for the array of phytophagous insects that use th em.