The Sunn pest, Eurygaster integriceps (Hemiptera: Scutelleridae), is the severe pest of cereals, especially of wheat in many parts of the world. Many insect species, including the Sunn pest that feed solely on nutritionally restricted diets, harbor symbiotic microorganisms. In the current study, we isolated and identified the Sunn pest bacterial symbionts of gut fractions and ovary. The phylogenetic analysis indicated that Sunn pest gut bacterial symbionts are polyphyletic and contained a taxonomic diversity belonging to three different phyla, including Firmicutes, Tenericutes, and Proteobacteria. Firmicutes was represented by Enterococcus, Proteobacteria by Pantoea and Acetobacteraceae, and Tenericutes by Spiroplasma. We isolated and identified Enterococcus, Acetobacteraceae, Spiroplasma and Pantoea from Sunn pest different gut compartments, and Pantoea from ovaries. There was considerable overlap between recognized symbionts from the 2nd and 3rd midgut sections (Acetobacteraceae), the 4th midgut section and hindgut (Spiroplasma), and 4th midgut section and ovary (Pantoea). Niche heterogeneity within a microbial habitat of gut fractions resulted in colonizing and adaptation of various communities of symbionts in each fraction. The Sunn pest gut compartments and ovary symbionts have been demonstrated to be of multiple evolutionary origins. This diversity may be of great importance to the Sunn pest fitness and survival in various overwintering niches.

Sun害虫Eurygaster integriceps（Hemiptera：Scutelleridae）是谷物的严重害虫，在世界许多地方尤其是小麦。许多昆虫物种，包括仅靠营养限制的饮食为食的Sun虫，都带有共生微生物。在本研究中，我们分离并鉴定了肠部分和卵巢的Sunn害虫细菌共生体。系统发育分析表明，Sunn害虫肠道细菌共生体是多系统的，并且具有属于三种不同门的分类学多样性，包括Firmicutes，Teneercutes和Proteobacteria。硬膜菌以肠球菌为代表，变形杆菌以泛菌和醋杆菌科为代表，而Tenericutes则以螺旋体为代表。我们隔离并确定了来自Sunn的肠球菌，醋杆菌科，螺旋体和泛菌害虫不同的肠腔，而卵巢中的泛菌。在第2和第3肠中段（醋杆菌科），第4肠中段和后肠（Spiroplasma）以及第4肠中段和子房（Pantoea）之间的公认共生体之间有大量重叠）。肠道级分微生物生境中的生态位异质性导致每个级分中共生菌的各种群落定居和适应。Sunn虫害肠道区隔和卵巢共生体已被证明具有多种进化起源。这种多样性对于Sunn害虫在各种越冬生态位中的适应性和生存至关重要。