The nervous system of the desert locust,Schistocerca gregaria(Orthoptera: Acrididae) with a discussion on muscle innervation

Abstract

Summary A detailed illustrated account of the nervous system in S. gregaria is given. The central, peripheral and sympathetic nervous systems have been described. The central and peripheral nervous systems comprise the brain, ventral nerve cord, suboesophageal, three thoracic and five abdominal ganglia and their nerves to different parts of the body. The brain consists of proto, deuto and tritocerebrum. The suboesophageal ganglion lies below the oesophagus and is connected to the tritocerebral lobes by a pair of connectives. This ganglion gives off a pair of recurrent nerves and seven pairs of nerves supplying the mouthparts, cervical muscles, salivary ducts and prothoracic ventral longitudinal muscles. The first or prothoracic ganglion gives off a pair of recurrent nerves and five pairs of nerves supplying different prothoracic muscles, sensillae of the prosternum and forelegs. The second or mesothoracic ganglion also gives off a pair of recurrent nerves and five pairs of nerves innervating hypodermis, forewings, middle legs, different muscles of the mesothorax and the chordotonal organ. The third or metathoracic ganglion gives off five pairs of metathoracic nerves and six pairs of abdominal nerves; the thoracic nerves supply the hindwings, metasternal sensillae, various muscles and hindlegs while the abdominal nerves include dorsal and ventral nerves of the first, second and third abdominal segments supplying the abdominal muscles, pleuron, tympanum and spiracles. The dorsal nerves of the second to eighth abdominal segments form VNABIC which supply the lateral muscles and spiracle in the respective segment. The first four abdominal ganglia, i.e. fourth, fifth, sixth and seventh abdominal ganglia give off one dorsal and one ventral nerve supplying the dorsal and ventral muscles in the respective segment. In the female the ventral nerve of the seventh abdominal ganglion also innervates the oviduct. The eighth abdominal ganglion gives off six pairs of nerves which supply the muscles of the eighth, ninth and tenth abdominal segments, epiproct, paraproct, cerci and rectum. This ganglion in the male also supplies the complex genital organ and in the female sends nerves to different valves of the ovipositor. The sympathetic nervous system is divisible into stomatogastric nervous system consisting of frontal ganglion, oesophageal ganglion, hypocerebral ganglion and their nerves and ventral sympathetic nervous system comprising a single median nerve, transverse nerves and paramedian nerves.