头喙亚目（半翅目）昆虫口器的功能形态和进化研究

Mouthparts are among the most important sensory and feeding structures in insects and differ according to differences in feeding behavior and habits. The hemipteran suborder Auchenorrhyncha are highly diverse and form a major component of the plant-feeding fauna of most terrestrial ecosystems. Many species are economically import as either direct plant pests or as vectors of plant pathogens. The structures of the mouthparts vary between different species and that some such differences are related to differences in feeding behavior. Comparative morphological study of the mouthparts may not only help explain differences in feeding behavior and diet breadth among species, but also found new evidences to reveal the evolutionary relationships among the remaining controversial taxa. This project will provide the first comparative study on fine structure and detailed phylogenetic analyses of auchenorrhyncha mouthpart and examine relationships within this lineage using scanning electron microscopy, Transmission electron microscope and Micro CT. This research on mouthpart morphology focuses on fine morphology and ultrastructure, with emphasis on differences in the shape of labrum and labium, pattern and distribution of the triangular cuticular processes on labrum, the shape, number and distribution of sensilla on labium, the teeth-like projections and serrate flanges on mandibular and maxillary stylets. The aims of this study are to elucidate and compare mouthpart morphology to determine whether they show mouthpart diversity that can be applied in the systematics of the Auchenorrhyncha suborder. Moreover, It will provide insights into feeding mechanisms and coevolution between mouthparts and foods in comparison of feeding behavior, combined with differences in mouthparts.

口器作为昆虫的取食器官，在漫长的进化过程中因食性和取食方式的不同发生了显著的分化。头喙亚目（半翅目）昆虫许多种类是重要的农林业害虫，不但刺吸植物汁液造成危害，而且传播植物病毒病，其口器因取食植物的种类、取食行为等不同而产生了相应的适应性分化。研究其口器的功能形态学，对于了解刺吸式害虫口器的适应演化和取食为害具有重要意义，同时为揭示尚存争议高级类群间的演化关系提供口器方面的新证据。本研究拟对头喙亚目昆虫不同类群的口器进行扫描、透射电镜和显微CT观察，掌握头喙亚目各类群口器的外部形态特征和超微结构，重点明确上唇、下唇的形态，感器的形态、分布与种类在不同科、属之间的差异，通过对口器形态特征的比较为高级阶元演化提供新的证据，并通过头喙亚目不同类群昆虫的取食行为的比较，并结合口器的结构变化，探讨口器与食物的协同进化关系，揭示该类害虫的取食机制，为探讨半翅目昆虫的起源与演化及防治该类害虫提供理论基础。

口器作为昆虫的取食器官，在漫长的进化过程中因食性和取食方式的不同发生了显著的分化。头喙亚目(半翅目)昆虫许多种类是重要的农林业害虫，不但刺吸植物汁液造成危害，而且传播植物病毒病。刺吸式口器是头喙亚目昆虫高度发育的取食器官，在寄主植物选择、取食和传播植物病毒等方面扮演着重要角色。研究其口器的功能形态学，对于了解刺吸式害虫口器的适应演化和取食为害具有重要意义，同时为揭示尚存争议高级类群间的演化关系提供口器方面的新证据。本研究利用扫描电子显微镜、投射电镜和显微CT对头喙亚目昆虫各类群代表种的口器进行了超微全形态观察，对比口器结构在不同种类及类群中的形态变化，重点明确上唇、下唇的形态，上、下颚口针的形态，感器的形态、分布与种类在不同科、种之间的差异。并基于超微形态的观察与分析，选取85个口器形态特征，对蝉次目昆虫进行系统发育分析，结果支持头喙亚目各总科的单系性，叶蝉科和角蝉科互为姊妹群，头喙亚目四个总科之间的关系为，蜡蝉总科位于基部，其它三个总科聚为一支为，（蝉总科+沫蝉总科）+角蝉总科。口器形态从蝉总科到角蝉总科呈现出连续的变化趋势：昆虫个体由大到小，口器长度由长到短；上唇形状从铲状到三角锥状变化，两侧缘片状突逐渐变窄直至消失，表面感器的数量由多到少，表皮突起数量由少到多；下唇逐渐变短，由第三节最长逐渐变为三节近等长，感器数量逐渐减少，第二节腹面末端延伸结构逐渐明显；下唇端部背腹感区分界逐渐不明显，感器逐渐减少，感器由成组分布变为圆周分布，表皮突起逐渐减少；上颚口针端部越来越尖锐，背部脊起逐渐增多，两侧齿突越来越明显；下颚口针之间的连锁结构逐渐减少，两侧脊上齿纹和沟槽逐渐消失，中脊上的齿纹趋于平缓，端部中脊上缺口从无到有。本研究首次运用比较形态学获取口器的形态和解剖学特征并进行系统发育分析，基于口器特征重建了头喙亚目昆虫系统发育关系，为揭示头喙亚目具争议高级类群间的演化关系提供口器方面的新证据。