Ultrastructure of the uniporous sensilla on the galea of larval Mamestra configurata (Walker) (Lepidoptera: Noctuidae)

The structure and innervation of sensilla on the galea of fifth-instar Bertha armyworms, Mamestra configurata, were examined using bright-field light, scanning electron, and transmission electron microscopy. Four sensillar types were identified. The galea bears two uniporous styloconic sensilla, one aporous spire-shaped basiconic sensillum, two aporous basiconic sensilla, and one campaniform sensillum. The uniporous styloconic sensillum consists of a small socketed peg inserted into a large cone or style. Each styloconic sensillum is innervated by five bipolar neurons and associated with three sheath cells. Four distal dendrites end in the peg at various levels beneath the pore and the fifth ends in a tubular body at the base of the peg. The intermediate and outer sheath cells enclose a very large liquor-filled sensillar sinus. The inner sheath cell forms a nonlapped cylindrical sleeve around the neurons. These sensilla exhibit features of contact chemosensilla.