Diversity in attachment devices of aquatic insects in a torrential hill stream of mid Himalaya

Present study was carried out to explore the morphological attachment devices od seven aquatic insect larvae or naiads (representing four orders of Ephemeroptera, Plecoptera, Trichoptera, and Hemiptera) along the swift water current of Binwa, a mid-Himalayan hill stream using scanning electron microscopy (SEM) images. Water current showed direct relation with slope/gradient and volume of water in stream. Samples were collected at four sites located at different attitude along the stream. The collected larvae or naiads have many morphological features, including adhesive pad, friction pad, serrated tarsal claw, bifid tarsal claw, tarsal claw with clamp, sucker, and serrated spines which serve as their adaptations for the fast-flowing waters. Principal Component Analysis revealed the importance of water current for assemblage and abundance of these aquatic insects, as it directly related to TDS, electric conductivity, turbidity and nutrients level in stream water, and cumulatively affect these aquatic macroinvertebrates. Similarities in structures of different species suggest the convergent evolution, while slight differences inferred as specializations for species specific niche of these organisms in stream habitat.