Integrative taxonomy tests possible hybridisation between Central Asian cerambycids (Coleoptera)

Hybridisation can lead to the formation of new evolutionary lineages and some described insect species may in fact be first-generation hybrids of their parental species. Anoplistes forticornis and A. galusoi are two closely related cerambycid taxa endemic to Central Asia that exhibit a peculiar geographical distribution. Although the common diagnostic elytral pattern makes these beetles superficially easily distinguishable, there are marked resemblances in their morphology. By applying an integrative taxonomy approach, we verify the taxonomic status of A. forticornis and A. galusoi and test the possibility of hybridisation. The results of our comprehensive morphological examination and molecular analyses targeting mitochondrial (COI, 16S rRNA) and nuclear (arginine kinase, CAD, 28S rRNA) genes support the specific status of these taxa. In mtDNA, the putative hybrid specimen is more closely related to A. forticornis, which indicates that a female of this species bred with a male of A. galusoi. The supposed ecotypic variability (manifested in elytral pattern) is apparently not related to the topography or spatial structure of habitat. The phylogenetic hypothesis supports a peripatric scenario in which populations of the common ancestor had been separated for a significant period of time, first by the mountain ranges of Dzungarian Alatau (~11–10 Ma) and ultimately by the Ili River. The diverged taxa came into recent secondary contact following these isolation events. The methodology presented herein can be widely applied to identify first-generation hybridisation in Coleoptera.     

A preliminary phylogenetic analysis of ribbed-pine-borer (Rhagium inquisitor) based on mitochondrial COI sequences

The increased volume of intercontinental-trade had facilitated the distribution of species, including invaders. Wooden packaging materials, goods and timber are being transported via international ports in East of the Marmara Basin, where has vast forests. That forests provide an appropriate-mediator for the introduction and invasion of wood-boring insects, which are the most common group being transported between continents. One of them is Rhagium inquisitor, which has a pivotal role in wood decay, nevertheless, it is detrimental for industrial wood.We analyzed the 654 bp length of cytochrome c oxidase I (COI) gene, to determine native and introduced haplotypes of the ribbed-pine-borer, to investigate their phylogenetic relationships and possibly cryptic speciation of the morphospecies.It was found out that sixteen haplotypes were divided into five haplogroups. The groups were assembled on two main lineages: Eurasian and American. The genetic distance between the American (Groups 1–3), Asian (Group-4) and European (Group-5) clusters ranged from 3 to 10%; between haplotypes ranged from 0.2 to 10.9%. The distances between the specimens of the Marmara Basin (H9-12, Group-4) were lower compared to H16, which nested in Group-5. That haplotype was sampled on imported timber and was found out that it is shared between France, Germany, Italy, and Austria. Maximum Likelihood, Neighbor-Joining and Bayesian Inference trees showed the same topologies, and Median-Joining network also supported them.Contrary to the usual, our findings point out that some species might have been introduced from Europe to Asia. Furthermore, the high genetic diversity of the bark-runner between continents could be a sign of cryptic-allopatric speciation.     

Differential expression of HSP70 and SAPK/JNK genes in the cabbage aphid upon salicylic and dilute sulfuric acid treatments in canola

Investigating the interaction between insect pests and host plants at molecular level, provides an insight for effective implementation of plant resistance-based strategies in insect pest control programs. Heat shock proteins (HSPs) are found in all living organisms which protect them from biotic and abiotic stresses. Stress-activated protein kinases (SAPKs) are members of MPK kinases which also are activated upon cellular stresses. We investigated the effect of seed-primed canola plants with salicylic acid (SA) and the plants treated with dilute sulfuric acid on the regulation of two stress-related genes, HSP70 and SAPK/JNK genes in the cabbage aphid. The results of qRT-PCR revealed a statistically significant up-regulation of HSP70 gene expression in aphids feeding on sulfuric acid-treated plants in comparison with controls (P < 0.01). However, this gene was not regulated in aphids feeding on salicylic acid-treated plants. In addition, quantification of SAPK/JNK gene showed a significant effect in aphids feeding on SA-primed plants (P < 0.05) and a marginally significant effect in sulfuric acid treatment. Further, the expression of both genes were significantly changed in interaction effect between SA and sulfuric acid treatments. Finally, the induction of HSP70 and SAPK/JNK genes in this research might be related to activation of systemic acquired resistance in canola.     

Identification and evaluation of reference genes for gene expression analysis in the weevil pest Pagiophloeus tsushimanus using RT-qPCR

Pagiophloeus tsushimanus is a newly and specialist wood-boring beetle of Cinnamomum camphora in China. RT-qPCR is an accurate quantitative method to quantify target genes expression, which relies on suitable reference genes for data normalization. Reference genes must to be stably expressed under specific experimental conditions. No suitable reference genes of P. tsushimanus have been reported so far. Therefore, it is necessary to identify and evaluate suitable reference genes for the study of functional genes of this pest. In this research, the expression stability of eight candidate reference genes (RPS3, 18S rRNA, GAPDH, TBP, RPL10, UBQ, GST, and RPS27A) were systematically evaluated in P. tsushimanus by five algorithms (geNorm, BestKeeper, NormFinder, delta C_q, and RefFinder) under different developmental stages, various tissues, and insects reared on different plants, and validated by the olfactory key gene odorant binding protein 33 (PtsuOBP33). The results showed that three stable reference genes combination were necessary for quantitative analysis of target gene. RPS3, RPL10, and UBQ were the optimal reference genes combination for gene expression analysis of developmental stages, while RPL10, RPS3, and 18S rRNA were recommended for different tissues, and 18S rRNA, TBP, and RPS3 were recommended for insects reared on different plants. The results indicated that suitable reference genes should be screened out for gene expression analysis under different conditions. This paper systematically analyzed and obtained suitable reference genes in P. tsushimanus for the first time, which would contribute to the functional analysis of genes and the in-depth mining of genetic resources in it.     

Divergent evolutionary histories of two sympatric spruce bark beetle species

Ips typographus and Pityogenes chalcographus are two sympatric Palearctic bark beetle species with wide distribution ranges. As both species are comparable in biology, life history, and habitat, including sharing the same host, Picea abies, they provide excellent models for applying a comparative approach in which to identify common historical patterns of population differentiation and the influence of species-specific ecological characteristics. We analysed patterns of genetic diversity, genetic structure and demographic history of ten I. typographus and P. chalcographus populations co-distributed across Europe using both COI and ITS2 markers. Rather than similarities, our results revealed striking differences. Ips typographus was characterised by low genetic diversity, shallow population structure and strong evidence that all extant haplogroups arose via a single Holocene population expansion event. In contrast, genetic variation and structuring were high in P. chalcographus indicating a longer and more complex evolutionary history. This was estimated to be five times older than I. typographus, beginning during the last Pleistocene glacial maximum over 100 000 years ago. Although the expansions of P. chalcographus haplogroups also date to the Holocene or just prior to its onset, we show that these occurred from at least three geographically separated glacial refugia. Overall, these results suggest that the much longer evolutionary history of P. chalcographus greatly influenced the levels of phylogeographic subdivision among lineages and may have led to the evolution of different life-history traits which in turn have affected genetic structure and resulted in an advantage over the more aggressive I. typographus.     

A new species of gall midge (Diptera: Cecidomyiidae) damaging flower buds of goji berry Lycium barbarum (Solanaceae)

Larvae of a previously undescribed gall midge species have been feeding within malformed flower buds of goji berry Lycium barbarum L. (Solanaceae) in China, preventing fruit development and causing damage to the fruit industry. The new species is named Gephyraulus lycantha Jiao & Kolesik, its morphology is described, the COI mitochondrial gene segment is sequenced, and the biology is outlined. In order to taxonomically accommodate the new gall midge, the scope of the genus Gephyraulus is broadened and now encompasses also species that lack dorso-apical sensoria on the female cercus.LSID: urn:lsid:zoobank.org:pub:17B243CF-5235-405B-AA60-8E872C848367.     

Ophiostomatoid fungi associated with hardwood-infesting bark and ambrosia beetles in Poland: Taxonomic diversity and vector specificity

Fungi in the orders Ophiostomatales and Microascales (Ascomycota), often designated as ophiostomatoid fungi, are frequent associates of scolytine bark and ambrosia beetles that colonize hardwood and coniferous trees. Several species, e.g., Ophiostoma novo-ulmi, are economically damaging pathogens of trees. Because little is known regarding the ophiostomatoid fungi in Europe, we have explored the diversity of these fungi associated with hardwood-infesting beetles in Poland. This study aims to clarify the associations between fungi in the genera Ambrosiella, Graphium (Microascales), Graphilbum, Leptographium, Ophiostoma and Sporothrix (Ophiostomatales) and their beetle vectors in hardwood ecosystems. Samples associated with 18 bark and ambrosia beetle species were collected from 11 stands in Poland. Fungi were isolated from adult beetles and galleries. Isolates were identified based on morphology, DNA sequence comparisons for five gene regions (ITS, LSU, ßT, TEF 1-α, and CAL) and phylogenetic analyses. In total, 36 distinct taxa were identified, including 24 known and 12 currently unknown species. Several associations between fungi and bark and ambrosia beetles were recorded for the first time. In addition, associations between Dryocoetes alni, D. villosus, Hylesinus crenatus, Ernoporus tiliae, Pteleobius vittatus and ophiostomatoid fungi were reported for the first time, and Sporothrix eucastanea was reported for the first time outside of the USA. Among the species of Ophiostomatales, 14 species were in Ophiostoma s. l., two species were in Graphilbum, nine species were in Sporothrix, and seven species were in Leptographium s. l. Among the species of Microascales, three species were in Graphium, and one was in Ambrosiella. Twenty taxa were present on the beetles and in the galleries, twelve only on beetles, and four only in galleries. Bark and ambrosia beetles from hardwoods appear to be regular vectors, with ophiostomatoid fungi present in all the beetle species. Most ophiostomatoid species had a distinct level of vector/host specificity, although Ophiostoma quercus, the most frequently encountered species, also had the greatest range of beetle vectors and tree hosts. Plant pathogenic O. novo-ulmi was found mainly in association with elm-infesting bark beetles (Scolytus multistriatus, S. scolytus, and P. vittatus) and occasionally with H. crenatus on Fraxinus excelsior and with Scolytus intricatus on Quercus robur.     

Nematodes associated with the double‐spined bark beetle Ips duplicatus (Coleoptera: Curculionidae) in central Europe

Ips duplicatus (Sahlberg) is an important forest pest in central Europe, but its nematode associates have seldom been studied. Therefore, nematodes associated with I. duplicatus were determined at three localities in the Czech Republic. The percentage of beetles with phoretic nematodes ranged from 18 to 65%. Micoletzkya buetschlii and other phoretic nematodes were found under elytra, on wings, and between body segments. The percentage of beetles with nematodes in the haemocoel ranged from 3 to 30%, and the nematodes included Contortylenchus diplogaster and Parasitylenchus cf. aculeatus. Juveniles of Parasitorhabditis obtusa (Fuchs 1915) were found in the intestines of 0–16% of the beetles. The most abundant species in I. duplicatus galleries were P. obtusa and M. buetschlii. Cryptaphelenchus sp., Parasitaphelenchus sp. and unidentified tylenchid juveniles also were found in the galleries. The percentage of beetles with nematodes was greater in the overwintering than in the offspring generation, and numbers of nematodes per gallery increased with gallery development.