Sensillar types of the ovipositor of Dasineura brassicae: structure and relation to oviposition behaviour

ABSTRACT. The distal part of the ovipositor of Dasineura brassicae Winn. (Diptera; Cecidomyiidae) possesses forty to forty-five sensilla of three morphological types. Most are provided with a cuticular bristle, which projects from the surface of the ovipositor; fifteen have a taste/tactile function based on fine structural characteristics; about twenty-five are innervated by a single sensory cell, specialized for mechanoreception. Scolopidial sensory receptors are anchored to the cuticle inside the distal part of the ovipositor, they probably respond to changes in length of the ovipositor. Different sensory systems are involved in the choice of oviposition site; compound eyes and antennae are probably active in the earlier stages, whereas the receptors of the ovipositor appear well suited to govern the last steps in this behaviour.