LAUSR

Insect extraordinary evolutionary success is due to different reasons among which their ability to receive and respond to a great variety of sensory cues thanks to their developed sense organs encompassing a high number of diversified sensilla, mainly located on their antennae. The successful invasion of lotic and lentic freshwaters by terrestrial insect required physiological constraints also regarding sensory systems. This chapter reviews the present knowledge about antennal sensory equipment in adult and aquatic stages of Ephemeroptera, Odonata, Plecoptera and Trichoptera. These insect orders have aquatic larval stages well adapted to this environment, while they move to the terrestrial habitat as adults. To be able to receive sensory cues in two very different biotopes during the young and the adult stage is a fundamental prerequisite for these insects. The data reported are mainly based on morphological investigations under scanning and transmission electron microscope (SEM, TEM), and behavioural and electrophysiological investigations (the latter available only for Odonata and Plecoptera). The chapter considers separately the main sensory capacities located on the antennae in the above-reported aquatic insect orders, in particular mechanoreception, chemoreception, thermo-hygroreception and their modifications from the aquatic to the adult stage.