Wang Yan, Brożek Jolanta, Dai Wu
Key Laboratory of Plant Protection Resources and Pest Integrated Management of the Ministry of Education, College of Plant Protection, Northwest A&F University, Yangling 712100, Shaanxi, China.
Faculty of Natural Science, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia in Katowice, Bankowa 9, 40-007 Katowice, Poland.
Insects. 2020 Feb 26;11(3):145. doi: 10.3390/insects11030145.
Mouthpart structures were observed in four species of Largidae using scanning electron microscopy to investigate their morphological disparity, and linked to changes in feeding specialization. The examined species are pests that feed mainly on seeds and plant sap of forbs, shrubs, and trees. Their external mouthparts are described in detail for the first time herein. The cone-like labrum and four-segmented tube-like labium are shorter in species than in (Grey). The labium surface in all studied species bears nine types of sensilla (St1-St2, Sb1-3, Sch, Sca1-2, Sm). The distributions of sensilla on particular labial segments varies among the studied species. The tripartite apex of the labium consists of two lateral lobes and an apical plate that is partly divided in species, and not divided in . Each lateral lobe possesses a sensillar field with 10 thick-walled uniporous sensilla basiconica, one multiporous sensillum styloconicum, and one long non-porous hair sensillum. Each mandibular stylet tip in has a central tooth placed anteriorly and pairs of teeth arranged dorso-laterally. In , there are one or two central teeth placed anteriorly but two pairs of teeth dorso-laterally. In all studied species, the inner surfaces of the mandibular stylets have scale-like projections. A left-right asymmetry of the maxillary stylets is noticeable; the external end of the right maxillary stylet is smooth and slightly tapered in and evidently wider (spoon-like) in the three species of , while the left end of the stylets is straight and narrow in in contrast to , in which the end is straight and wide. No differences in the internal structure of the maxillary stylets were observed among the studied species. Based on structural differences, we inferred that the mandibles and maxillae are more adapted for seed-sucking in species than in has the ends of the maxillae more narrowed, a trait more adapted for sucking sap from phloem or parenchymal cells.
使用扫描电子显微镜观察了四种硕蝽科昆虫的口器结构，以研究它们的形态差异，并将其与取食特化的变化联系起来。所研究的物种是主要以草本植物、灌木和树木的种子及植物汁液为食的害虫。本文首次详细描述了它们的外部口器。在[具体物种1]中，锥状上唇和分四节的管状下唇比[具体物种2（灰色）]中的短。在所有研究物种中，下唇表面有九种类型的感器（St1 - St2、Sb1 - 3、Sch、Sca1 - 2、Sm）。在所研究的物种中，特定唇节上感器的分布各不相同。下唇的三分顶端由两个侧叶和一个顶端板组成，在[具体物种1]中顶端板部分分开，在[具体物种2]中不分开。每个侧叶都有一个感器场，有10个厚壁单孔锥形感器、一个多孔柱形感器和一个长的无孔毛状感器。在[具体物种1]中，每个下颚口针尖端前方有一个中央齿，背侧有一对齿。在[具体物种2]中，前方有一个或两个中央齿，但背侧有两对齿。在所有研究物种中，下颚口针的内表面有鳞片状突起。上颚口针明显存在左右不对称；在[具体物种1]中，右上颚口针的外端光滑且略呈锥形，在[具体物种2]的三个物种中明显更宽（勺状），而在[具体物种1]中口针的左端是直的且窄，相比之下，在[具体物种2]中其末端是直的且宽。在所研究的物种中，未观察到上颚口针内部结构的差异。基于结构差异，我们推断，与[具体物种2]相比，[具体物种1]的下颚和上颚更适应吸食种子；[具体物种2]的上颚末端更窄，这一特征更适合从韧皮部或薄壁细胞中吸食汁液。
