Studies On The External Morphology And Internal Structure Of Psammotettix Striatus (L.)

The leafhopper Psammotettix striatus (L.) (Hemiptera: Cicadellidae) distributes worldwide and vectors a phytoplasma that causes wheat blue dwarf (WBD), a severe disease limiting wheat production in the Western China. The external morphology and internal structure of P. striatus (L.) were studied in this paper, including ultrastructure of antenna and mouthpart, nymphs morphology and internal structure.Antenna consists of basal scape, pedicel and long flagellum. Numerous wrinkle and cuticular denticles are distributed on the short scape and pedicel, and 3-5 sensilla trichodea on the apex of pedicel. Slender flagellum is composed of many segments. Three sensilla basiconic are distributed on the 1st, 2nd and 4th segment of flagellum respectively, one sensilla trichodea on the 3rd segment. A few types and number of sensilla are same on female and male. There is no difference between adults and nymphs in the distribution, number and types of antennal sensillum.The mouthparts of P. striatus (L.) resemble those of other piercing-sucking insect pests, consisting of a tube-like structure including the labrum, labium and a stylet fascicle comprising two mandibular and two maxillary stylets. The three-segmented labium has a deep longitudinal groove on the ventral surface, within which lies the stylet fascicle, consisting of two inner maxillary stylets partially surrounded by two somewhat shorter and serrate-edgesd mandibular stylets, and above which is a small cone-shaped labrum. The labium is covered with two types of sensillum, sensilla trichodea and sensilla basiconic, symmetrically positioned on either side of the labial groove or arranged on the distal end. The maxillary stylets are interlocked to form 2 separate compartments, a larger food canal and a smaller salivary canal. Two dendritic canals are also found in each maxilla and one in each mandible.Detailed morphological descriptions and figures of the nymphs of Psammotettix striatus (L.) are provided for the first time in this paper. The nymph development of P. striatus (L.) consists of five instars. There are many differences between nymphs and adult. The nymphs have no wings or only have wing pads, fewer stripes on bodies, anteclypeus and postclypeus rise and cover most of the face, tarsi are only two-segmented in each thoracic leg, immature genitalia. From 1st to 5th instar, the heads gradual widen, proportion of gena in face increase, the wing pads appear in the 2nd and then extend gradually, the abdomen is covered with 4 longitudinal rows of setae and additional setae in the hind angles of tergites VII-VIII.The digestive system of P. striatus (L.) contains salivary gland and alimentary canal. The latter consists of mouth, oesophagus, midgut, hindgut and rectum. The esophagus is a narrow tube originating from the pharynx and extending to the anterior midgut below the filter chamber. Two salivary glands are located on each side of the head, and each gland consists of principal and accessory glands. The anterior midgut is a large sac-like structure extending from the metathorax through the entire length of the abdomen, and then ascends backward to the anterior of the midgut to form the filter chamber. Hindgut is a slender tubule, extends to the rectum. There are four Malpighian tubes.Male reproductive system of P. striatus (L.) contains testes, vas deferens, accessory gland, seminal vesicle and ejaculatory duct. Each testis consists of six testicular follicles which are sphere-shaped and unsheathed. Two seminal vesicle are egg-shaped, and a pair of accessory glands arise at the posterior of each seminal vesicle and open into the lateral ejaculatory duct. The female reproductive system is ordinary, which contains ligament, ovary, lateral oviduct, common oviduct, spermatheca, accessory gland. The ovaries contain six telotrophic type ovarioles and each ovariole usually contains only one egg.