Sensory armature and stylets of the mouthparts of Stephanitis nashi (Hemiptera: Cimicomorpha: Tingidae), their morphology and function.

Mouthparts are important appendages that are specialized for detection of food sources and feeding. The pear lace bug, Stephanitis nashi Esaki and Takeya, is a major pest of pear in China, sucking the sap and affecting plant growth. Fine structure of the mouthparts including distribution and abundance of receptor sensilla occurring of adult S. nashi was examined using scanning electron microscopy and structural details are described for the first time. The mouthparts of S. nashi are generally similar to those of other Hemiptera and consist of a pyramidal labrum, a tube-like segmented labium, and a stylet fascicle made up of two mandibular and two maxillary stylets. The four segments of the labium differ in length and have five classes of sensilla including 3 types of sensilla basiconica (I, II, III), 2 types of sensilla trichodea (I, II), 1 type of sensillum campaniformium, 1 type of flower-like sensillum and a sensillum placodeum. Sensilla trichodea II are distributed on each segment of the labium. Sensilla basiconica I occur on the base of the second and fourth segment. The labial tripartite apex composes of two sensory fields and a rostral lid. Each sensory field possesses 2 sensilla basiconica II, 9 sensilla basiconica III, 1 flower-like sensillum and 1 sensillum placodeum. The mandibular stylet tips have about 30 pairs of lateral minor teeth, which may help in penetrating leaves. Externally, the end of each maxillary stylet is smooth; internally it has five teeth. There is no obvious difference between males and females in the distribution, number and types of sensilla. The mouthparts morphology of S. nashi, is consistent in many respects to that of many other phytophagous hemipterans but appear to include some features unique to the Tingidae and others that closely resemble those of both phytophagous and predaceous Miridae.