[Histological observation of the central nervous system in Simulium (Wilhelmia) xingyiense (Diptera:Simuliidae)].
To investigate the morphological characters of the central nervous system in mature larvae, mature pupae and newly emerged adults of Simulium (Wilhelmia) xingyiense. From August to November 2009, the blackfly larvae were collected from the rivulets nearby Niujiao Island in Huaxi of Guiyang City. The mature larvae of S. (Wi.) xingyiense were confirmed based on the diagnostic characteristics of gill spots, postgenal cleft, and rectal gill. The mature pupae were obtained from the rivulets of Da'ao Town and Qingyan Town in Guiyang in March 2011, which were selected according to the characteristics of cocoon and respiratory filaments. Nervous system of the larvae, pupae and newly emerged adults was observed under the light microscope with HE-stained paraffin sections. The central nervous system was composed of brain, subesophageal ganglion and ventral nerve cord. The brain of the larva was divided into two narrowly interconnected egg-shaped lobes. Ventral nerve-cord of the larva consisted of three pairs of thoracic ganglia and eight pairs of abdominal ganglia. The brain of the pupa and adult was composed of protocerebuim, deutocerebrum, and tritocerebrum. The ventral nerve cord of the pupa and adult was similar to that of larva. From outside to inside, the structure characters of the brain and ganglia were similar with nerve sheath, neurocyte and neuropile. The neuropile of protocerebrum contained a pair of mushroom bodies, a central complex and a pair of accessory lobes. The optic lobe was composed of medulla interna, medulla externa and lamina ganglionaris. The deutocerebrum consisted of the antennal lobe and the dorsal lobe. The tritocerebrum connected to the subesophageal ganglion by perioperative esophageal nerve. The central nervous system of S. (Wi.) xingyiense is similar to other simuliid blackilies. There is a difference in the number of abdominal ganglion of the mature larva.