Parallel metatranscriptome analysis reveals degradation of plant secondary metabolites by beetles and their gut symbionts.

Switching to a new host plant is a driving force for divergence and speciation in herbivorous insects. This process of incorporating a novel host plant into the diet may require a number of adaptations in the insect herbivores that allow them to consume host plant tissue that may contain toxic secondary chemicals. As a result, herbivorous insects are predicted to have evolved efficient ways to detoxify major plant defences and increase fitness by either relying on their own genomes or by recruiting other organisms such as microbial gut symbionts. In the present study we used parallel metatranscriptomic analyses of Altica flea beetles and their gut symbionts to explore the contributions of beetle detoxification mechanisms versus detoxification by their gut consortium. We compared the gut meta-transcriptomes of two sympatric Altica species that feed exclusively on different host plant species as well as their F1 hybrids that were fed one of the two host plant species. These comparisons revealed that gene expression patterns of Altica are dependent on both beetle species identity and diet. The community structure of gut symbionts was also dependent on the identity of the beetle species, and the gene expression patterns of the gut symbionts were significantly correlated with beetle species and plant diet. Some of the enriched genes identified in the beetles and gut symbionts are involved in the degradation of secondary metabolites produced by plants, suggesting that Altica flea beetles may use their gut microbiota to help them feed on and adapt to their host plants.

Complete mitochondrial genome of Distenia punctulatoides (Coleoptera: Chrysomeloidea: Disteniinae) and its phylogenetic implications.

The family Disteniidae is a moderately large and widely distributed lineage. Distenia punctulatoides belongs to the family Disteniidae from the cerambycoid assemblage. Here, we report the complete mitogenome of D. punctulatoides, which is 15,675 bp in length. It contains 37 genes and a noncoding control region, which are arranged in the same order as that of the putative ancestor of beetles. The total base composition of the new mitogenome is 40.2% for A, 17.1% for C, 10.0% for G, and 32.7% for T. The new mitogenomic organization, nucleotide composition, and codon usage do not differ significantly from other beetles. Using available complete mitogenomes, the high-level phylogeny of the family Disteniidae was explored. The phylogenetic analyses showed that Disteniidae were monophyletic, and the genus Distenia grouped with the genus Clytomelegena as sister groups. Combining the morphological and molecular data, Typodryas Thomson, 1864 is suggested to be a junior synonym of Distenia Lepeletier and Audinet-Serville, 1828.

The draft genome of the specialist flea beetle Altica viridicyanea (Coleoptera: Chrysomelidae).

BACKGROUND: Altica (Coleoptera: Chrysomelidae) is a highly diverse and taxonomically challenging flea beetle genus that has been used to address questions related to host plant specialization, reproductive isolation, and ecological speciation. To further evolutionary studies in this interesting group, here we present a draft genome of a representative specialist, Altica viridicyanea, the first Alticinae genome reported thus far. RESULTS: The genome is 864.8 Mb and consists of 4490 scaffolds with a N50 size of 557 kb, which covered 98.6% complete and 0.4% partial insect Benchmarking Universal Single-Copy Orthologs. Repetitive sequences accounted for 62.9% of the assembly, and a total of 17,730 protein-coding gene models and 2462 non-coding RNA models were predicted. To provide insight into host plant specialization of this monophagous species, we examined the key gene families involved in chemosensation, detoxification of plant secondary chemistry, and plant cell wall-degradation. CONCLUSIONS: The genome assembled in this work provides an important resource for further studies on host plant adaptation and functionally affiliated genes. Moreover, this work also opens the way for comparative genomics studies among closely related Altica species, which may provide insight into the molecular evolutionary processes that occur during ecological speciation.

Gut bacterial communities and their contribution to performance of specialist Altica flea beetles.

Host plant shifts are a common mode of speciation in herbivorous insects. Although insects can evolve adaptations to successfully incorporate a new host plant, it is becoming increasingly recognized that the gut bacterial community may play a significant role in allowing insects to detoxify novel plant chemical defenses. Here, we examined differences in gut bacterial communities between Altica flea beetle species that feed on phylogenetically unrelated host plants in sympatry. We surveyed the gut bacterial communities of three closely related flea beetles from multiple locations using 16S rRNA amplicon sequencing. The results showed that the beetle species shared a high proportion (80.7%) of operational taxonomic units. Alpha-diversity indicators suggested that gut bacterial diversity did not differ among host species, whereas geography had a significant effect on bacterial diversity. In contrast, analyses of beta-diversity showed significant differences in gut bacterial composition among beetle species when we used species composition and relative abundance metrics, but there was no difference in composition when species presence/absence and phylogenetic distance indices were used. Within host beetle species, gut bacterial composition varied significantly among sites. A metagenomic functionality analysis predicted that the gut microbes had functions involved in xenobiotic biodegradation and metabolism as well as metabolism of terpenoids and polyketides. These predictions, however, did not differ among beetle host species. Antibiotic curing experiments showed that development time was significantly prolonged, and there was a significant decline in body weight of newly emerged adults in beetles lacking gut bacteria, suggesting the beetles may receive a potential benefit from the gut microbe-insect interaction. On the whole, our results suggest that although the gut bacterial community did not show clear host-specific patterns among Altica species, spatiotemporal variability is an important determinant of gut bacterial communities. Furthermore, the similarity of communities among these beetle species suggests that microbial facilitation may not be a determinant of host plant shifts in Altica.

Large-scale 3D imaging of insects with natural color.

High-resolution 3D imaging technology has found a number of applications in many biological fields. However, the existing 3D imaging tools are often too time-consuming to use on large-scale specimens, such as centimeter-sized insects. In addition, most 3D imaging systems discard the natural color information of the specimens. To surmount these limitations, we present a structured illumination-based approach capable of delivering large field-of-view three-dimensional images. With this approach, 580nm lateral resolution full-color 3D images and 3D morphological data in the size range of typical insect samples can be obtained. This method provides a promising approach that can be used to support many different types of entomological investigations, including taxonomy, evolution, bionics, developmental biology, functional morphology, paleontology, forestry, etc.

The phylogeny of Galerucinae (Coleoptera: Chrysomelidae) and the performance of mitochondrial genomes in phylogenetic inference compared to nuclear rRNA genes.

With efficient sequencing techniques, full mitochondrial genomes are rapidly replacing other widely used markers, such as the nuclear rRNA genes, for phylogenetic analysis but their power to resolve deep levels of the tree remains controversial. We studied phylogenetic relationships of leaf beetles (Chrysomelidae) in the tribes Galerucini and Alticini (root worms and flea beetles) based on full mitochondrial genomes (103 newly sequenced), and compared their performance to the widely sequenced nuclear rRNA genes (full 18S, partial 28S). Our results show that: (i) the mitogenome is phylogenetically informative from subtribe to family level, and the per-nucleotide contribution to nodal support is higher than that of rRNA genes, (ii) the Galerucini and Alticini are reciprocally monophyletic sister groups, if the classification is adjusted to accommodate several 'problematic genera' that do not fit the dichotomy of lineages based on the presence (Alticini) or absence (Galerucini) of the jumping apparatus, and (iii) the phylogenetic results suggest a new classification system of Galerucini with eight subtribes: Oidina, Galerucina, Hylaspina, Metacyclina, Luperina, Aulacophorina, Diabroticina and Monoleptina.

Visualization of the 3D structures of small organisms via LED-SIM.

BACKGROUND: Innovative new techniques that aid in the visualization of microscopic anatomical structures have improved our understanding of organismal biology significantly. It is often challenging to observe internal 3D structures, despite the use of techniques such as confocal laser scanning microscopy (CLSM), micro-computed tomography (Micro-CT), magnetic resonance imaging (MRI), focused ion beam scanning electron microscopy (FIB-SEM) and others. In the current paper, we assess LED-SIM (DMD-based LED-illumination structured illumination microscopy), which facilitates the acquisition of nano- and micro-3D structures of small organisms in a high-resolution format (500 nm in the XY-plane and 930 nm along the Z-axis). RESULTS: We compare other microstructural imaging techniques (involving conventional optical microscopy, CLSM and Micro-CT) with LED-SIM to assess the quality (e.g. resolution, penetration depth, etc.) of LED-SIM images, as well as to document the potential short-comings of LED-SIM. Based on these results we present an optimized set of protocols to ensure that LED-SIM arthropod and nematode samples with different cuticles or textures are prepared for analysis in an optimal manner. Six arthropod and nematode specimens were tested and shown to be suitable for LED-SIM imaging, which was found to yield high resolution 3D images. CONCLUSIONS: Although LED-SIM still must be thoroughly tested before it is widely accepted and the Z-axis resolution still requires improvement, this technique offers distinct high quality 3D images. LED-SIM can be highly effective and may provide high quality 3D images for zoological studies following the guidelines of sample preparation presented in the current paper.

Adaptation to different host plant ages facilitates insect divergence without a host shift.

Host shifts and subsequent adaption to novel host plants are important drivers of speciation among phytophagous insects. However, there is considerably less evidence for host plant-mediated speciation in the absence of a host shift. Here, we investigated divergence of two sympatric sister elm leaf beetles, Pyrrhalta maculicollis and P. aenescens, which feed on different age classes of the elm Ulmus pumila L. (seedling versus adult trees). Using a field survey coupled with preference and performance trials, we show that these beetle species are highly divergent in both feeding and oviposition preference and specialize on either seedling or adult stages of their host plant. An experiment using artificial leaf discs painted with leaf surface wax extracts showed that host plant chemistry is a critical element that shapes preference. Specialization appears to be driven by adaptive divergence as there was also evidence of divergent selection; beetles had significantly higher survival and fecundity when reared on their natal host plant age class. Together, the results identify the first probable example of divergence induced by host plant age, thus extending how phytophagous insects might diversify in the absence of host shifts.

Mandible evolution in the Scarabaeinae (Coleoptera: Scarabaeidae) and adaptations to coprophagous habits.

INTRODUCTION: The astonishing spectrum of scarabaeine lifestyles makes them an attractive group for studies in entomology and evolutionary biology. As a result of adaptions to specific food substrates and textures, the mouthparts of dung beetles, particularly the mandible, have undergone considerable evolutionary changes and differ distinctly from the presumptive ancestral conditions of the Coleoptera and Polyphaga. The possible functions of dung beetle mouthparts and the evolution of dung feeding have been controversial for decades. RESULTS: In this study, 187 scarabs representing all tribes of the Scarabaeinae and the major lineages within the Scarabaeoidea, along with three major feeding types within the Scarabaeoidea (omnivory, phytophagy and coprophagy), were studied. Based on geometric morphometric and three-dimensional (3D) reconstruction approaches, morphological differences in mandibles among the three feeding types were identified. The ancestral forms of the mandible within the Scarabaeinae were reconstructed and compared with those of modern species. The most recent common ancestor of the Scarabaeinae fed on soft materials, and the ancestor of the Scarabaeinae and the Aphodiinae was in an evolutionary transition between processing more solid and softer substrates. CONCLUSIONS: Coprophagy originated from omnivorous ancestors that were very likely saprophagous. Furthermore, phytophagy may also have originated from omnivory. In addition, our study addresses the integration and modularity of geometric morphometric data in a phylogenetic context.

The thorax of Mantophasmatodea, the morphology of flightlessness, and the evolution of the neopteran insects.

Mantophasmatodea was described as a new insect order in 2002. Since then, this small group of wingless insects has developed into one of the best investigated insect taxa. Nevertheless, many aspects of mantophasmatodean morphology as well as their evolutionary relationships remain ambiguous. To determine the phylogenetic relationships of Mantophasmatodea based on an extended character set and to elucidate possible morphological adaptions towards flightlessness, we investigated the thoracic morphology of two species, Austrophasma caledonensis and Mantophasma sp. The morphological similarity between these two species is striking and no differences in musculature were found. The mantophasmatodean thorax strongly resembles that of ice crawlers (Grylloblattodea), especially with respect to the presence of pleural processes in the meso- and metathorax, branched furcae in all segments, and similar muscle equipment. In a cladistic analysis containing all major lineages of Neoptera, the monophyly of Polyneoptera is supported by the presence of an anal fan and several modifications of the wing joint. Within Polyneoptera, a sister-group relationship between stoneflies and the remaining Polyneoptera is supported. A clade comprising Mantophasmatodea and the Grylloblattodea gains strong support from thoracic morphology and can be considered assured. Potential thoracic apomorphies include prothoracic paracoxal invaginations, pterothoracic pleural arms that originate from the epimeron, and a unique metathoracic sterno-coxal musculature. The monophyly of Orthoptera and Dictyoptera is further supported while the deeper polyneopteran nodes remain unresolved. Among the wingless taxa investigated we found few general morphological adaptations whereas, in other aspects, especially in the musculature, strong differences could be observed. However, much more research on the strongly neglected topic of flightlessness is required to make reliable statements.

Endogenous cellulolytic enzyme systems in the longhorn beetle Mesosa myops (Insecta: Coleoptera) studied by transcriptomic analysis.

The Cerambycidae (longhorn beetle) is a large family of Coleoptera with xylophagous feeding habits. Cellulose digestion plays an important role in these wood-feeding insects. In this study, transcriptomic technology was used to obtain one glycoside hydrolase family 45 (GH45) cellulase and seven GH5 cellulases from Mesosa myops, a typical longhorn beetle. Analyses of expression dynamics and evolutionary relationships provided a complete description of the cellulolytic system. The expression dynamics related to individual development indicated that endogenous GH45 and GH5 cellulases dominate cellulose digestion in M. myops. Evolutionary analyses suggested that GH45 cellulase gene is a general gene in the Coleoptera Suborder Polyphaga. Evolutionary analyses also indicated that the GH5 cellulase group in Lamiinae longhorn beetles is closely associated with wood feeding. This study demonstrated that there is a complex endogenous cellulolytic system in M. myops that is dominated by cellulases belonging to two glycoside hydrolase families.

Penghou, a new genus of flea beetles from China (Coleoptera: Chrysomelidae: Galerucinae: Alticini).

A new genus (Penghou) with a single new species (P. yulongshan) from Yunnan Province in China is described and illustrated. It is compared to Hespera Weise, Hesperomorpha Ogloblin, Laotzeus Chen, Luperomorpha Weise, Mandarella Duvivier, Omeiana Chen, Stenoluperus Ogloblin and Taiwanohespera Kimoto.

Notes on Lycocerus kiontochananus (Pic, 1921) and description of two new species of Lycocerus Gorham from China (Coleoptera, Cantharidae).

The Lycocerus kiontochananus species complex is revised; L. perroudi (Pic, 1937) stat. rev., originally in Cantharis, is resurrected from synonymy with L. kiontochananus (Pic, 1921); L. atropygidialis (Pic, 1937) stat. nov., originally in Cantharis, is upgraded from Cantharis perroudi var. atropygidialis Pic, 1937 and resurrected from synonymy with L. kiontochananus; L. kejvali Svihla, 2004 syn. nov. is considered as a junior synonym with L. kiontochananus. The male of L. perroudi and the female of L. jendeki Svihla, 2005 are described for the first time. Two new species are described under the names of L. metalliceps sp. nov. (China: Sichuan) and L. hainanus sp. nov. (China: Hainan).

A Review of Chinese Species of the Genus Oides Weber, 1801 (Coleoptera: Chrysomelidae: Galerucinae).

In this study, 25 species of Oides Weber from China were reviewed. Among them, the following seven new species are described: Oides angustasp. nov., O. cystoprocessasp. nov., O. paraborerisp. nov., O. parabowringiisp. nov., O. parathibettanasp. nov., O. shimenensissp. nov., and O. yunnanensissp. nov.; Oides innocua Gahan has been recorded in China for the first time. A key to all the Chinese Oides species is provided.

A taxonomic study on the nominate subgenus Macrolycus Waterhouse, 1878 from China (Coleoptera, Lycidae).

In the present study, a new species of Macrolycus s. str. is reported from China and described as M. subapicis sp. nov. M. bowringi Waterhouse, 1878 is recorded to China for the first time. The above two species, M. oreophilus Kazantsev, 2002 and M. gansuensis Kazantsev, 2002 are illustrated with the male habitus and genitalia. In addition, a distribution map, and a key to the species of Macrolycus s. str. in the world are provided.

A review of the leaf-beetle genus Sinoluperus Gressitt & Kimoto, 1963 (Coleoptera, Chrysomelidae, Galerucinae) from China, with the description of a new species.

In this study, all species of the leaf-beetle genus Sinoluperus Gressitt & Kimoto, 1963 from China are redescribed based on the reexamination of type specimens, and a new species, S.variegatussp. nov. from Nanling Mountains, is described. A key to the three Chinese species of Sinoluperus is provided, as well as photographs of the habiti and aedeagi of these species.

Five new species of the Macrolycusligulatus species-group from China (Coleoptera, Lycidae).

Five new species of the Macrolycusligulatus species-group, M.expansus sp. nov., M.quartus sp. nov., M.costus sp. nov., M.opacipennis sp. nov. and M.curtus sp. nov., are reported from China and described with macrophotographs of the habitus of both sexes and aedeagi. Macrolycusguangxiensis Li, Bocak & Pang, 2015 is illustrated showing the female habitus and genitalia for the first time. In addition, a distribution map and a key to all species of the M.ligulatus species-group are provided.

Taxonomic review of the genus Ponyalis Fairmaire, 1899 (Coleoptera, Lycidae), with descriptions of six new species from China.

The lycid genus Ponyalis Fairmaire, 1899 is reviewed. Six new species are described from China, including P.longicornis sp. nov., P.truncata sp. nov., P.dabieshanensis sp. nov., P.hainanensis sp. nov., P.quadricollimima sp. nov., and P.zhejiangensis sp. nov. Nine previously known species, including P.alternata (Pic, 1927), P.fukiensis (Bocak, 1999), P.gracilis (Bocak, 1999), P.himalejica (Bourgeois, 1885), P.klapperichi (Bocak, 1999), P.laticornis Fairmaire, 1899, P.nigrohumeralis (Pic, 1939), P.quadricollis (Kiesenwetter, 1874), and P.variabilis Li, Bocak & Pang, 2015 are illustrated with images of the habitus and aedeagi to make the comparisons with the new species. In addition, a distribution map and an identification key to all 24 species of Ponyalis are provided.

Study on fluid inclusions and stable isotopics of W-Mo ore deposits in the Ningshan-Zhen'an area, South Qinling, China.

The study of the fluid inclusions of W-Mo deposits in the mineralization area of Ningshan-Zhen'an , Shaanxi Province, China shows that the gas-liquid two-phase inclusions are mainly present in W-Mo deposits, and the ore-forming fluid can be divided into four types: high-temperature type, middle-high-temperature type, middle-temperature type and low-temperature type. The formation depths of the W-Mo mineralization range from 4.2 to 8.4 km. The boiling and mixing of fluid may have been important mechanisms for the formation of W-Mo mineralization. The skarn-type mineralization is dominated by magmatic water, the quartz-vein-type mineralization includes both magmatic water and meteoric water, and the meteoric water is more involved in the quartz-fluorite-vein-type, beryl-quartz-vein-type and pegmatite-type mineralization. Magma is the main source of sulfur; that is, magma is the main source of mineralization. Combined with the metallogenic setting and geological characteristics of typical ore deposits, in the process of structural system transformation in South Qinling, the ore-forming magma fluid in the Late Indosinian-Yanshanian period was uplifted and emplaced along the NW-WNW direction and NE-NNE direction, and eventually, NW-WNW fault-controlled skarn-type W-Mo mineralization and quartz-vein-type W-Mo deposits accompanied by greisenization, albitization and potash feldspathization formed.

Evolutionary radiation strategy revealed in the Scarabaeidae with evidence of continuous spatiotemporal morphology and phylogenesis.

Evolutionary biology faces the important challenge of determining how to interpret the relationship between selection pressures and evolutionary radiation. The lack of morphological evidence on cross-species research adds to difficulty of this challenge. We proposed a new paradigm for evaluating the evolution of branches through changes in characters on continuous spatiotemporal scales, for better interpreting the impact of biotic/abiotic drivers on the evolutionary radiation. It reveals a causal link between morphological changes and selective pressures: consistent deformation signals for all tested characters on timeline, which provided strong support for the evolutionary hypothesis of relationship between scarabs and biotic/abiotic drivers; the evolutionary strategies under niche differentiation, which were manifested in the responsiveness degree of functional morphological characters with different selection pressure. This morphological information-driven integrative approach sheds light on the mechanism of macroevolution under different selection pressures and is applicable to more biodiversity research.