DNA barcoding of the genus Gampsocleis (Orthoptera, Tettigoniidae) from China

DNA barcoding is a useful addition to the traditional morphology-based taxonomy. A ca. 650 bp fragment of the 5' end of mitochondrial cytochrome c oxidase subunit I (hereafter COI-5P) DNA barcoding was sued as a practical tool for Gampsocleis species identification. DNA barcodes from 889 specimens belonging to 8 putative Gampsocleis species was analyzed, including 687 newly generated DNA barcodes. These barcode sequences were clustered/grouped into Operational Taxonomic Units (OTUs) using the criteria of five algorithms, namely Barcode Index Number (BIN) System, Assemble Species by Automatic Partitioning (ASAP), a Java program uses an explicit, determinate algorithm to define Molecular Operational Taxonomic Unit (jMOTU), Generalized Mixed Yule Coalescent (GMYC), and Bayesian implementation of the Poisson Tree Processes model (bPTP). The Taxon ID Tree grouped sequences of morphospecies and almost all MOTUs in distinct nonoverlapping clusters. Both long- and short-winged Gampsocleis species are reciprocally monophyletic in the Taxon ID Tree. In BOLD, 889 barcode sequences are assigned to 17 BINs. The algorithms ASAP, jMOTU, bPTP and GMYC clustered the barcode sequences into 6, 13, 10, and 23 MOTUs, respectively. BIN, ASAP, and bPTP algorithm placed three long-winged species, G. sedakovii, G. sinensis and G. ussuriensis within the same MOTU. All species delimitation algorithms split two short-winged species,G. fletcheri and G. gratiosa into at least two MOTUs each, except for ASAP algorithm. More detailed molecular and morphological integrative studies are required to clarify the status of these MOTUs in the future.

Mwhitiwhiti Aotearoa: Phylogeny and synonymy of the silent alpine grasshopper radiation of New Zealand (Orthoptera: Acrididae)

Aotearoa New Zealand has a fauna of endemic alpine grasshoppers, consisting of thirteen species distributed among four genera. The many re-classifications of species within this group and the presence of species complexes highlight the uncertainty that surrounds relationships within and between these genera. High-throughput Next Generation Sequencing was used to assemble the complete mitochondrial genomes, 45S ribosomal cassettes and histone sequences of New Zealands four endemic alpine genera: Alpinacris, Brachaspis, Paprides and Sigaus. Phylogenetic analysis of these molecular datasets, as individual genes, partitions and combinations returned a consistent topology that is incompatible with the current classification. The genera Sigaus, Alpinacris, and Paprides all exhibit paraphyly. A consideration of the pronotum, epiphallus and terminalia of adult specimens reveals species-specific differences, but fails to provide compelling evidence for species groups justifying distinct genera. In combination with phylogenetic, morphological and spatial evidence we propose a simplified taxonomy consisting of a single genus for the mwhitiwhiti Aotearoa species radiation.

Mitogenome of Xya pfaendleri (Orthoptera: Caelifera): Its comparative description and phylogenetic position within Tridactylidea

We report the comparative examination of the complete mitochondrial genome of the pygmy mole cricket Xya pfaendleri (Orthoptera: Caelifera: Tridactylidae). The mitogenome consists of 13 protein-coding regions, 22 tRNAs, two rRNAs, and one control region, following the gene order of the ancestral pancrustacean mitogenome. The length of the mitogenome in Xya pfaendleri is 15352 bp. The start and stop codons of the protein-coding genes exhibit the general pattern observed in orthopterans. The data indicate that the pattern of gene overlapping/intergenic sequences exhibits a significant phylogenetic signal. A phylogenetic tree inferred using 12 mitogenomes (seven belonging to Tridactylidea, three to Acrididea, and two to Ensifera) confirms the sister group relationship of Acrididea and Tridactylidea. The relationship among the families of Tridactylidea is Cylindrachetidae + (Ripipterygidae + Tridactylidae). The mitogenome sequences of Xya and Tridactylus constitute a single clade, sharing a last common ancestor 94 million years ago, and rendering the first genus paraphyletic. The present preliminary data suggest that we still have much to learn about the evolution and diversity of Tridactylidea.

Two new species of the genus Diestramima from China (Orthoptera: Rhaphidophoridae: Aemodogryllinae)

The genus Diestramima comprises 41 species from Asia with 31 species distributed in China. In this study, we reconstruct the phylogeny tree of Diestramima species by maximum likelihood and Bayesian inference based on three mitochondrial genes (COI, 12S and 16S). The result indicates that the phylogenetic results are coherent with that based on five molecular markers (COI, 12S, 16S, 18S and 28S). Moreover, two new species, D. pingmengensis sp. nov. He & Zong and D. gulinjingensis. sp. nov. Zong & He are described. Their validities are also supported by morphological features. Furthermore, D. sichuanensis Zhu & Shi, 2022 is treated as a junior synonym of D. guangxiensis Qin, Wang, Liu & Li, 2016 based on both morphological and molecular features.

New reports on Chinese Anelytra species (Orthoptera, Tettigoniidae: Conocephalinae)

Based on the former studies and new material, Anelytra (Euanelytra) eunigrifrons Ingrisch, 1998 is reported in China for the first time. In addition, the female sex of Anelytra (Euanelytra) spinia Shi & Qiu, 2009 is described. We also confirmed that Anelytra (Euanelytra) spinia Shi & Qiu, 2009 is mainly distributed in Southern China. The examined specimens are deposited in Guangxi Normal University.

New estimates of genome size in Orthoptera and their evolutionary implications

Animal genomes vary widely in size, and much of their architecture and content remains poorly understood. Even among related groups, such as orders of insects, genomes may vary in size by orders of magnitude-for reasons unknown. The largest known insect genomes were repeatedly found in Orthoptera, e.g., Podisma pedestris (1C = 16.93 pg), Stethophyma grossum (1C = 18.48 pg) and Bryodemella holdereri (1C = 18.64 pg). While all these species belong to the suborder of Caelifera, the ensiferan Deracantha onos (1C = 19.60 pg) was recently found to have the largest genome. Here, we present new genome size estimates of 50 further species of Ensifera (superfamilies Gryllidea, Tettigoniidea) and Caelifera (Acrididae, Tetrigidae) based on flow cytometric measurements. We found that Bryodemella tuberculata (Caelifera: Acrididae) has the so far largest measured genome of all insects with 1C = 21.96 pg (21.48 gBp). Species of Orthoptera with 2n = 16 and 2n = 22 chromosomes have significantly larger genomes than species with other chromosome counts. Gryllidea genomes vary between 1C = 0.95 and 2.88 pg, and Tetrigidae between 1C = 2.18 and 2.41, while the genomes of all other studied Orthoptera range in size from 1C = 1.37 to 21.96 pg. Reconstructing ancestral genome sizes based on a phylogenetic tree of mitochondrial genomic data, we found genome size values of >15.84 pg only for the nodes of Bryodemella holdereri / B. tuberculata and Chrysochraon dispar / Euthystira brachyptera. The predicted values of ancestral genome sizes are 6.19 pg for Orthoptera, 5.37 pg for Ensifera, and 7.28 pg for Caelifera. The reasons for the large genomes in Orthoptera remain largely unknown, but a duplication or polyploidization seems unlikely as chromosome numbers do not differ much. Sequence-based genomic studies may shed light on the underlying evolutionary mechanisms.

Evolution of Gene Arrangements in the Mitogenomes of Ensifera and Characterization of the Complete Mitogenome of Schizodactylus jimo

Gene arrangement (relative location of genes) is another evolutionary marker of the mitogenome that can provide extensive information on the evolutionary mechanism. To explore the evolution of gene arrangements in the mitogenome of diversified Ensifera, we sequenced the mitogenome of the unique dune cricket species found in China and used it for phylogenetic analysis, in combination with 84 known Ensiferan mitogenomes. The mitogenome of Schizodactylus jimo is a 16,428-bp circular molecule that contains 37 genes. We identified eight types of gene arrangement in the 85 ensiferan mitogenomes. The gene location changes (i.e., gene translocation and duplication) were in three gene blocks: I-Q-M-ND2, rrnl-rns-V, and ND3-A-R-N-S-E-F. From the phylogenetic tree, we found that Schizodactylus jimo and most other species share a typical and ancient gene arrangement type (Type I), while Grylloidea has two types (Types II and III), and the other five types are rare and scattered in the phylogenetic tree. We deduced that the tandem replication–random loss model is the evolutionary mechanism of gene arrangements in Ensifera. Selection pressure analysis revealed that purifying selection dominated the evolution of the ensiferan mitochondrial genome. This study suggests that most gene rearrangements in the ensiferan mitogenome are rare accidental events.

MtOrt: an empirical mitochondrial amino acid substitution model for evolutionary studies of Orthoptera insects

BACKGROUND

Amino acid substitution models play an important role in inferring phylogenies from proteins. Although different amino acid substitution models have been proposed, only a few were estimated from mitochondrial protein sequences for specific taxa such as the mtArt model for Arthropoda. The increasing of mitochondrial genome data from broad Orthoptera taxa provides an opportunity to estimate the Orthoptera-specific mitochondrial amino acid empirical model.

RESULTS

We sequenced complete mitochondrial genomes of 54 Orthoptera species, and estimated an amino acid substitution model (named mtOrt) by maximum likelihood method based on the 283 complete mitochondrial genomes available currently. The results indicated that there are obvious differences between mtOrt and the existing models, and the new model can better fit the Orthoptera mitochondrial protein datasets. Moreover, topologies of trees constructed using mtOrt and existing models are frequently different. MtOrt does indeed have an impact on likelihood improvement as well as tree topologies. The comparisons between the topologies of trees constructed using mtOrt and existing models show that the new model outperforms the existing models in inferring phylogenies from Orthoptera mitochondrial protein data.

CONCLUSIONS

The new mitochondrial amino acid substitution model of Orthoptera shows obvious differences from the existing models, and outperforms the existing models in inferring phylogenies from Orthoptera mitochondrial protein sequences.

Mitochondrial genome characterization of the family Trigonidiidae (Orthoptera) reveals novel structural features and nad1 transcript ends

The Trigonidiidae, a family of crickets, comprises 981 valid species with only one mitochondrial genome (mitogenome) sequenced to date. To explore mitogenome features of Trigonidiidae, six mitogenomes from its two subfamilies (Nemobiinae and Trigonidiinae) were determined. Two types of gene rearrangements involving a trnN-trnS1-trnE inversion and a trnV shuffling were shared by Trigonidiidae. A long intergenic spacer was observed between trnQ and trnM in Trigonidiinae (210-369 bp) and Nemobiinae (80-216 bp), which was capable of forming extensive stem-loop secondary structures in Trigonidiinae but not in Nemobiinae. The anticodon of trnS1 was TCT in Trigonidiinae, rather than GCT in Nemobiinae and other related subfamilies. There was no overlap between nad4 and nad4l in Dianemobius, as opposed to a conserved 7-bp overlap commonly found in insects. Furthermore, combined comparative analysis and transcript verification revealed that nad1 transcripts ended with a U, corresponding to the T immediately preceding a conserved motif GAGAC in the superfamily Grylloidea, plus poly-A tails. The resultant UAA served as a stop codon for species lacking full stop codons upstream of the motif. Our findings gain novel understanding of mitogenome structural diversity and provide insight into accurate mitogenome annotation.

Innate releasing mechanisms and fixed action patterns: basic ethological concepts as drivers for neuroethological studies on acoustic communication in Orthoptera

This review addresses the history of neuroethological studies on acoustic communication in insects. One objective is to reveal how basic ethological concepts developed in the 1930s, such as innate releasing mechanisms and fixed action patterns, have influenced the experimental and theoretical approaches to studying acoustic communication systems in Orthopteran insects. The idea of innateness of behaviors has directly fostered the search for central pattern generators that govern the stridulation patterns of crickets, katydids or grasshoppers. A central question pervading 50 years of research is how the essential match between signal features and receiver characteristics has evolved and is maintained during evolution. As in other disciplines, the tight interplay between technological developments and experimental and theoretical advances becomes evident throughout this review. While early neuroethological studies focused primarily on proximate questions such as the implementation of feature detectors or central pattern generators, later the interest shifted more towards ultimate questions. Orthoptera offer the advantage that both proximate and ultimate questions can be tackled in the same system. An important advance was the transition from laboratory studies under well-defined acoustic conditions to field studies that allowed to measure costs and benefits of acoustic signaling as well as constraints on song evolution.

Biased dispersal of Metrioptera bicolor, a wing dimorphic bush-cricket

In the highly fragmented landscape of central Europe, dispersal is of particular importance as it determines the long-term survival of animal populations. Dispersal not only secures the recolonization of patches where populations went extinct, it may also rescue small populations and thus prevent local extinction events. As dispersal involves different individual fitness costs, the decision to disperse should not be random but context-dependent and often will be biased toward a certain group of individuals (e.g., sex- and wing morph-biased dispersal). Although biased dispersal has far-reaching consequences for animal populations, immediate studies of sex- and wing morph-biased dispersal in orthopterans are very rare. Here, we used a combined approach of morphological and genetic analyses to investigate biased dispersal of Metrioptera bicolor, a wing dimorphic bush-cricket. Our results clearly show wing morph-biased dispersal for both sexes of M. bicolor. In addition, we found sex-biased dispersal for macropterous individuals, but not for micropters. Both, morphological and genetic data, favor macropterous males as dispersal unit of this bush-cricket species. To get an idea of the flight ability of M. bicolor, we compared our morphological data with that of Locusta migratoria and Schistocerca gregaria, which are very good flyers. Based on our morphological data, we suggest a good flight ability for macropters of M. bicolor, although flying individuals of this species are seldom observed.

Positive selection and comparative molecular evolution of reproductive proteins from New Zealand tree weta (Orthoptera, Hemideina)

Animal reproductive proteins, especially those in the seminal fluid, have been shown to have higher levels of divergence than non-reproductive proteins and are often evolving adaptively. Seminal fluid proteins have been implicated in the formation of reproductive barriers between diverging lineages, and hence represent interesting candidates underlying speciation. RNA-seq was used to generate the first male reproductive transcriptome for the New Zealand tree weta species Hemideina thoracica and H. crassidens. We identified 865 putative reproductive associated proteins across both species, encompassing a diverse range of functional classes. Candidate gene sequencing of nine genes across three Hemideina, and two Deinacrida species suggests that H. thoracica has the highest levels of intraspecific genetic diversity. Non-monophyly was observed in the majority of sequenced genes indicating that either gene flow may be occurring between the species, or that reciprocal monophyly at these loci has yet to be attained. Evidence for positive selection was found for one lectin-related reproductive protein, with an overall omega of 7.65 and one site in particular being under strong positive selection. This candidate gene represents the first step in the identification of proteins underlying the evolutionary basis of weta reproduction and speciation.

The complete mitochondrial genome of Spathosternum prasiniferum sinense Uvarov, 1931 (Orthoptera: Acridoidea: Acrididae)

The complete mitogenome of Spathosternum prasiniferum sinense was sequenced and annotated in this work. It is 15,591 bp in size and contains 37 typical animal mitochondrial genes, meanwhile, A + T content is high as 74.1%. All protein-coding genes (PCGs) use standard ATN initiation codons. Twelve PCGs utilize complete termination codons TAG or TAA, except for DN5 gene uses an incomplete stop codon TA. tRNA genes were predicted with a characteristic cloverleaf secondary structure except trnS(AGN). The sizes of the lrRNA and srRNA genes are 1315 and 788 bp, respectively. The AT content of the A + T-rich region is 86.5%.

A preliminary phylogeny of the South African Lentulidae

BACKGROUND

The grasshopper family Lentulidae is endemic to eastern and southern Africa, with its center of diversity situated in South Africa, the highest diversity being found in the Cape Floristic Region, which is one of the global biodiversity hotspots. The family consists of 35 genera sorted in two subfamilies. This study provides first insights into the phylogeny of Lentulidae. Two mitochondrial genes (12S and NDS) were sequenced and the phylogeny was inferred through Maximum Likelihood and Bayesian Inference.

RESULTS

Our results indicate that the current classification into the subfamilies Lentulinae and Shelforditinae may be incorrect as Uvarovidium, Leatettix (Shelforditinae) and Devylderia (Lentulinae) clustered together in one main clade, while Betiscoides, Basutacris and Gymnidium (all Lentulinae) formed the second main clade. The genera Uvarovidium and Leatettix, which had been assigned to the Acrididae (subfamily Hemiacridinae) in the past, grouped within the Lentulidae, confirming their current assignment to this family. The East African Usambilla group is likely to represent a sister clade to the south African Lentula and Eremidium. Diversification patterns in the genus Devylderia and Betiscoides suggest a higher number of species than currently known.

CONCLUSIONS

Our phylogeny is not in line with the current systematics of Lentulidae, suggesting that a broader sampling and a study of the genitalia would be useful to clarify the taxonomy. Furthermore, some genera (particularly Betiscoides and Devylderia) are in need of taxonomic revision, as the number of species within these genera is likely to be higher than the current taxonomy suggests.

Systematics of spiny predatory katydids (Tettigoniidae: Listroscelidinae) from the Brazilian Atlantic Forest based on morphology and molecular data

Listroscelidinae (Orthoptera: Tettigoniidae) are insectivorous Pantropical katydids whose taxonomy presents a long history of controversy, with several genera incertae sedis. This work focused on species occurring in the Brazilian Atlantic Forest, one of the world's most threatened biomes. We examined material deposited in scientific collections and visited 15 conservation units from Rio de Janeiro to southern Bahia between November 2011 and January 2012, catching 104 specimens from 10 conservation units. Based on morphological and molecular data we redefined Listroscelidini, adding a new tribe, new genus and eight new species to the subfamily. Using morphological analysis, we redescribed and added new geographic records for six species, synonymized two species and built a provisional identification key for the Atlantic Forest Listroscelidinae. Molecular results suggest two new species and a new genus to be described, possibly by the fission of the genus Hamayulus. We also proposed a 500 bp region in the final portion of the COI to be used as a molecular barcode. Our data suggest that the Atlantic Forest Listroscelidinae are seriously endangered, because they occur in highly preserved forest remnants, show high rates of endemism and have a narrow geographic distribution. Based on our results, we suggest future collection efforts must take into account the molecular barcode data to accelerate species recognition.

4-Methyl-1-hepten-3-one, the Defensive Compound from Agathemera elegans (Philippi) (Phasmatidae) Insecta

Insects of the genus Agathemera (Phasmatidae) live in the Chilean Andes over 1500 m above sea level. On disturbing, the insects release a spray that can cause temporary blindness in humans. Very little is known on the composition of chemicals used for defense by South American phasmids. Here we show that both female and male defensive secretion of Agathemera elegans is made up of 4-methyl-1-hepten-3-one. The compound is reported for the first time as a natural product.

The first mitochondrial genome for the superfamily Hagloidea and implications for its systematic status in Ensifera

Hagloidea Handlirsch, 1906 was an ancient group of Ensifera, that was much more diverse in the past extending at least into the Triassic, apparently diminishing in diversity through the Cretaceous, and now only represented by a few extant species. In this paper, we report the complete mitochondrial genome (mitogenome) of Tarragoilus diuturnus Gorochov, 2001, representing the first mitogenome of the superfamily Hagloidea. The size of the entire mitogenome of T. diuturnus is 16144 bp, containing 13 protein-coding genes (PCGs), 2 ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes and one control region. The order and orientation of the gene arrangement pattern is identical to that of D. yakuba and most ensiferans species. A phylogenomic analysis was carried out based on the concatenated dataset of 13 PCGs and 2 rRNA genes from mitogenome sequences of 15 ensiferan species, comprising four superfamilies Grylloidea, Tettigonioidae, Rhaphidophoroidea and Hagloidea. Both maximum likelihood and Bayesian inference analyses strongly support Hagloidea T. diuturnus and Rhaphidophoroidea Troglophilus neglectus as forming a monophyletic group, sister to the Tettigonioidea. The relationships among four superfamilies of Ensifera were (Grylloidea, (Tettigonioidea, (Hagloidea, Rhaphidophoroidea))).

Isolation and characterization of microsatellite loci for Stys's bush-cricket, Isophya stysi, and cross-species amplification in closely related species from the Phaneropteridae family

Ten microsatellite loci were isolated and characterized for Stys's bush-cricket, Isophya stysi Cejchan (Orthoptera: Tettigoniidae), an endemic Orthoptera species to the Carpathian Basin, using an enriched genomic library procedure. The polymorphism of these loci were tested in two populations of I. stysi, and the number of alleles per locus varied from 4 to 16. The expected and observed heterozygosities ranged from 0.612 to 0.925 and from 0.625 to 1.000, respectively. The interspecific applicability of these microsatellites was evaluated by amplification in 20 related species: Isophya camptoxypha, Isophya sicula, Isophya ciucasi, Isophya pienensis, Isophya harzi, Isophya kraussii, Isophya zubovskii, Isophya rectipennis, Isophya modesta, Isophya longicaudata, Isophya dobrogensis, Isophya hospodar, Isophya speciosa, Isophya modestior, Poecilimon fussii, Poecilimon affinis, Polysarcus denticauda, Barbitistes constrictus, Leptophyes discoidalis, Phaneroptera falcata. All primer pairs for the 10 loci yielded successful amplifications in at least one other taxon from the Isophya genus. This set of microsatellite loci would be useful for genetic studies in I. stysi and other species of the genus Isophya.

Development of novel microsatellite markers for the secret cave cricket, Ceuthophilus secretus

The secret cave cricket, Ceuthophilus secretes Scudder (Orthroptera: Rhaphidophoridae), is an obligate trogloxene endemic to central Texas, USA, and is a primary source of energy and nutrients for sensitive cave ecosystems. In this study, nine polymorphic microsatellite markers were developed from genomic DNA of C. secretes. Genotypes of 120 individuals sampled from four localities on the Fort Hood Military Reservation, Killeen, Texas, were analyzed to characterize the polymorphism at each locus. The number of alleles ranged from 19 to 46. All paired loci were in linkage equilibrium. Four loci had significant deviations from Hardy-Weinberg equilibrium. Observed heterozygosity varied from 0.793 to 0.959. These loci provide a means of characterizing population genetic structure in this species.

Microsatellite markers for the Chameleon grasshopper (Kosciuscola tristis) (Orthoptera: Acrididae), an Australian Alpine Specialist

A set of polymorphic loci was characterised using an enrichment library for the Australian alpine specialist, the chameleon grasshopper (Kosciuscola tristis), an atypical grasshopper known for its remarkable temperature-controlled colour change. The number of alleles per locus ranged from three to 20 and observed heterozygosity from 0.16 to 0.76. These are the first microsatellite markers for a non-endangered Australian alpine animal and will inform questions of gene flow across the sky islands of this unique and threatened region.

Re-visiting phylogenetic and taxonomic relationships in the genus Saga (Insecta: Orthoptera)

Twelve of the 13 bushcricket species of the Saga genus are bisexuals and diploids, except the parthenogenetic and tetraploid bush cricket, Saga pedo. Despite a continuous research effort stretching through the 1900s, the taxonomic relationships of the Saga species are still disputed. In this study, our primary aim was to reveal natural relationships of the European Saga species and three of their Asian relatives, with special attention to the problematic taxonomy of two subspecies: S. campbelli campbelli and S. c. gracilis. Following a phylogenetic analysis of eight species, a comprehensive study was carried out on the above three taxa by using acoustic and morphometric approaches in parallel. Our phylogenetic data showed that European Saga species evolved from a monophyletic lineage. The geographical transitional species S. cappadocica was positioned between European and Asian lineages supporting the idea that the European Saga lineage originated phylogeographically from the Asian clade. The above results showed better agreement with the morphological data than with earlier ones based either on karyology or acoustic information only. After reviewing our data, we concluded that Saga pedo has most likely evolved from S. c. gracilis and not from S. rammei or S. ephippigera, as proposed by earlier studies. S. c. gracilis shares the same ITS2 haplotype with S. pedo, indicating that the latter could have evolved from populations of the former, probably through whole genome duplication. Based on acoustic and morphometric differences, we propose to elevate the two subspecies, S. campbelli campbelli and S. c. gracilis, to species level status, as Saga gracilis Kis 1962, and Saga campbelli Uvarov 1921. The present work sets the stage for future genetic and experimental investigations of Saginae and highlights the need for additional comprehensive analysis involving more Asian Saga species.

Long microsatellites and unusually high levels of genetic diversity in the Orthoptera

Much remains to be learned about the mutational processes governing the evolution of microsatellite repeat regions and the associated levels of genetic diversity observed at microsatellite markers across populations or species. An extensive survey of microsatellite variation in 210 insect species from six major orders revealed that within Orthopterans, which are characterized by giant genomes, levels of genetic diversity were ~20% higher and microsatellite repeat arrays were longer than in any other group. Because of the mutation dependence on repeat length, this result suggests a higher microsatellite loci mutation rate in the Orthoptera. We deem it plausible that differences among insect orders, either in mismatch repair systems or in abundance of transposable element-derived microsatellites, can shape the size distribution of both genomes and microsatellite repeat regions. Our findings emphasise that observed levels of genetic diversity can greatly vary across species (orders at least) because of molecular differences in the mechanisms that determine microsatellite size, and are therefore critical to conservation and population genetics studies, where microsatellite repeat variability is primarily interpreted in terms of population demography and history.

Dual olfactory pathway in Hymenoptera: evolutionary insights from comparative studies

In the honeybee (Apis mellifera) and carpenter ant (Camponotus floridanus) the antennal lobe output is connected to higher brain centers by a dual olfactory pathway. Two major sets of uniglomerular projection neurons innervate glomeruli from two antennal-lobe hemispheres and project via a medial and a lateral antennal-lobe protocerebral tract in opposite sequence to the mushroom bodies and lateral horn. Comparison across insects suggests that the lateral projection neuron tract represents a special feature of Hymenoptera. We hypothesize that this promotes advanced olfactory processing associated with chemical communication, orientation and social interactions. To test whether a dual olfactory pathway is restricted to social Hymenoptera, we labeled the antennal lobe output tracts in selected species using fluorescent tracing and confocal imaging. Our results show that a dual pathway from the antennal lobe to the mushroom bodies is present in social bees, basal and advanced ants, solitary wasps, and in one of two investigated species of sawflies. This indicates that a dual olfactory pathway is not restricted to social species and may have evolved in basal Hymenoptera. We suggest that associated advances in olfactory processing represent a preadaptation for life styles with high demands on olfactory discrimination like parasitoism, central place foraging, and sociality.

Prevalence of B chromosomes in Orthoptera is associated with shape and number of A chromosomes

We analyze the prevalence of B chromosomes in 1,601 species of orthopteran insects where chromosome number and shape are known. B chromosomes have been reported in 191 of these species. Bs are not uniformly distributed among orthopteran superfamilies, with evident hotspots in the Pyrgomorphoidea (32.3% of species carrying Bs), Grylloidea (14.9%), Acridoidea (14.6%) and Tetrigoidea (14.3%). As expected under the theory of centromeric drive, we found a correlation between B chromosome presence and A chromosome shape-Bs are more frequent in karyotypes with more acrocentric A chromosomes. We also found that Bs are less common in species with high chromosome numbers and appear to be most common at the modal chromosome number (2n = 24). Study effort, measured for each genus, was not associated with B prevalence, A chromosome shape or A chromosome number. Our results thus provide support for centromeric drive as an important and prevalent force in the karyotypic evolution of Orthoptera, just as it appears to be in mammals. We suggest that centromeric drive may provide a mechanistic explanation for White's principle of karyotypic orthoselection.

Evolution of novel signal traits in the absence of female preferences in Neoconocephalus katydids (Orthoptera, Tettigoniidae)

Background Significance

Communication signals that function to bring together the sexes are important for maintaining reproductive isolation in many taxa. Changes in male calls are often attributed to sexual selection, in which female preferences initiate signal divergence. Natural selection can also influence signal traits if calls attract predators or parasitoids, or if calling is energetically costly. Neutral evolution is often neglected in the context of acoustic communication.

Methodology/Principal Findings

We describe a signal trait that appears to have evolved in the absence of either sexual or natural selection. In the katydid genus Neoconocephalus, calls with a derived pattern in which pulses are grouped into pairs have evolved five times independently. We have previously shown that in three of these species, females require the double pulse pattern for call recognition, and hence the recognition system of the females is also in a derived state. Here we describe the remaining two species and find that although males produce the derived call pattern, females use the ancestral recognition mechanism in which no pulse pattern is required. Females respond equally well to the single and double pulse calls, indicating that the derived trait is selectively neutral in the context of mate recognition.

Conclusions/Significance

These results suggest that 1) neutral changes in signal traits could be important in the diversification of communication systems, and 2) males rather than females may be responsible for initiating signal divergence.

Cytogenetics studies in Brazilian species of Pseudophyllinae (Orthoptera: Tettigoniidae): 2n(♂)=35 and fn=35 the probable basic and ancestral karyotype of the family Tettigoniidae

The karyotypes of five species of Brazilian Pseudophyllinae belonging to four tribes were here studied. The data available in the literature altogether with those obtained with species in here studied allowed us to infer that 2n(♂)=35 is the highest chromosome number found in the family Tettigoniidae and that it is present in species belonging to Pseudophyllinae, Zaprochilinae and in one species of Tettigoniinae. In spite of that all five species exhibit secondary karyotypes arisen surely by a mechanism of chromosomal rearrangement of centric fusion, tandem fusion and centric inversion types from those with 2n(♂)=35 and FN=35, they share some common traits. The X chromosome is submetacentric (FN=36), heteropicnotic during the first prophase, the largest of the set but its size is rather variable among the species and the sex chromosomal mechanism is of the XO( ♂ ), XX( ♀ ) type. The chromosomal rearrangements involved in the karyotype evolution of the Pseudophyllinae and its relationship with those of the family Tettigoniidae are discussed and we propose that the basic and the ancestral karyotype of the Tettigoniidae is formed by 2n(♂)=35, FN=35 and not by 2n(♂)=31, FN= 31, as usually accepted.

Relationship between incomplete synapsis and chiasma localization

One of the subjects within the meiotic field that has been actively investigated in the recent years is the temporal and functional relationships between meiotic recombination, cohesin loading and synaptonemal complex (SC) assembly. Although the study of meiotic mutants has shed some light, many questions remain to be answered. Here, we have studied this topic in the orthopteran Paratettix meridionalis, a species with telocentric chromosomes, which shows two unusual cytological features: pairing and synapsis of homologues during prophase I are restricted to the non-centromeric distal regions and extremely distal chiasma localization in metaphase I bivalents. In order to determine whether there is a relationship between both phenomena, we have used: (1) a spreading technique for following the ultrastructure of SC assembly and (2) immunofluorescence for SMC3 and SMC1alpha cohesin subunits, which mark the development of the axial element (a SC component); the histone gamma-H2AX, which mostly labels the sites of double-strand breaks; and the recombinase RAD51. Spermatocytes showed conspicuous polarization of both the maturation of cohesin axes and the initiation of meiotic recombination events. Consequently, it is proposed that maturation of cohesin axes, which begins in very distal regions, could drive the latter loading of recombinases to such regions. This restricted distribution of recombination events along homologues would finally be responsible for the incomplete pairing and synapsis observed in all autosomes of the complement and hence for chiasma localization.

Peptides of the adipokinetic hormone/red pigment-concentrating hormone family with special emphasis on Caelifera: primary sequences and functional considerations contrasting grasshoppers and locusts

The presented work is a hybrid of an overview and an original research paper. First, we review briefly the structure, biosynthesis, release, mode of action and function of those peptides that constitute the adipokinetic/red pigment-concentrating family. Second, we collate the data on primary sequences available for caeliferan orthoptera, i.e. grasshoppers and locusts, and add a number of new data from previously unpublished work. The data are interpreted in conjunction with morphological and molecular biology data with respect to phylogenetic relationships of these various taxa. Finally, we discuss the differences between the adipokinetic response of grasshoppers and locusts to corpus cardiacum extract or synthetic adipokinetic hormone with regard to flight ability, phase polymorphism, age, presence of adipokinetic hormones, lipophorin system and other parameters. It appears that the higher hyperlipaemic response is always correlated with pronounced flight ability.

Phylogenetic reconstruction of the family Acrypteridae (Orthoptera: Acridoidea) based on mitochondrial cytochrome B gene

Sequences from the mitochondrial cytochrome b gene (Cyt b) were determined for 25 species from the superfamily Acridoidae and the homologous sequences of 19 species of grasshoppers were downloaded from the GenBank data library. The purpose was to develop a molecular phylogeny of the Acrypteridae, and to interpret the phylogenetic position of the family within the superfamily Acridoidea. Phylogeny was reconstructed by Maximum-parsimony (MP) and Bayesian criteria using Yunnanites coriacea and Tagasta marginella as outgroups. The alignment length of the fragments was 384 bp after excluding ambiguous sites, including 167 parsimony informative sites. In the fragments, the percentages of A + T and G + C were 70.7% and 29.3%, respectively. The monophyly of Arcypteridae is not supported by phylogenetic trees. Within the Arcypteridae, neither Arcypterinae nor Ceracrinae is supported as a monophyletic group. The current genus Chorthippus is not a monophyletic group, and should be a polyphyletic group. The present results are significantly different from the classification scheme of Arcypteridae, which is based on morphology.

Complete mitochondrial genome of Oxya chinensis (Orthoptera, Acridoidea)

The complete sequence of Oxya chinensis (O. chinensis) mitochondrial genome is reported here. It is 15,443 bp in length and contains 75.9% A+T. The protein-coding genes have a similar A+T content (75.2%). The initiation codon of the cytochrome oxidase subunit I gene in the mitochondrial genome of O. chinensis appears to be ATC, instead of the tetranucleotides that have been reported in Locusta migratoria (L. migratoria) mitochondrial genome. The sizes of the large and small ribosomal RNA genes are 1319 and 850 bp, respectively. The transfer RNA genes have been modeled and showed strong resemblance to the dipteran transfer RNAs, and all anticodons are identical to those of dipteran. The A+T-rich region is 562 bp, shorter than that of other known Orthoptera insects. The six conserved domains were identified within the A+T-rich region by comparing its sequence with those of other grasshoppers. The result of phylogenetic analysis based on the dataset containing 12 concatenated protein sequences confirms the close relationship of O. chinensis with L. migratoria.

The complete mitochondrial genome of Deracantha onos (Orthoptera: Bradyporidae)

The complete mitochondrial genome 15,650 bp in size of the Deracantha onos has been determined. The gene content, base composition and codon usage of D. onos are coincident to typical hexapods mitochondrial genomes. Genes arrangement of D. onos is identical to Gryllotalpa orientalis, Ruspolia dubia and Anabrus simplex, in that the relative locations of tRNA(Lys) and tRNA(Asp) was different to that of Locusta migratoria. All tRNAs could be folded into the typical cloverleaf secondary structure, excluding tRNA(Ser(AGN)) which forms another structure according to the Steinberg-Cedergren tertiary structure. Sequence analysis of the A + T-rich region with Dot-plot did not find any conspicuous repeat clusters. Two poly-thymine (poly-T) nucleotide stretches of 20 bp and 11 bp in size, which may involved in the recognition of replication origin, were found on the H-strand and L-strand in the A + T-rich region of the D. onos mitogenome, respectively. One open reading frame (ORF) 87 amino acids in size was found on the H-strand, but Protein Blast searches analysis indicated that it was a nonfunctional ORF.

Polyandry in the wild: temporal changes in female mating frequency and sperm competition intensity in natural populations of the tettigoniidRequena verticalis

Empirical tests of sexual selection theory generally utilize model systems under laboratory settings, and extend conclusions to evolutionary processes occurring in nature. The biological significance of laboratory findings will depend largely on the mating rates of females and patterns of paternity in natural populations, information on which is generally lacking. Here we use microsatellite markers to provide rare estimates of female mating rates and patterns of parentage in a species of tettigoniid, Requena verticalis, which has been used extensively to test theory on the evolution of male parental investment and its influence on the direction of sexual selection. We found that although the number of males having a genetic representation in the female's sperm stores was higher for females collected late in the breeding season than those collected early in the season, overall the female mating rate was lower than that expected from laboratory observations. Analysis of parentage of offspring produced by females at the end of the breeding season revealed that all males represented in the sperm stores fathered offspring, although paternity was biased away from that expected from random sperm utilization. The data show that the complete first male sperm precedence documented in laboratory studies of this species does not persist in natural populations. Our data provide a solid underpinning for conclusions drawn from laboratory studies of this species.

The dynamics of sexual conflict over mating rate with endosymbiont infection that affects reproductive phenotypes

Maternally inherited endosymbionts have been implicated as significant drivers of sexual conflict within their hosts, typically through sex-ratio manipulation. Empirical studies show that some of these endosymbionts have the potential to influence sexual conflict not by sex-ratio distortion, but by altering reproductive traits within their hosts. Research has already shown that reproductive traits involved in mating/fertilization process are integral 'players' in sexual conflict, thus suggesting the novel hypothesis that endosymbiont-induced changes in reproductive phenotypes can impact the dynamics of sexual conflict. Here, we use a standard quantitative genetic approach to model the effects of endosymbiont-induced changes in a female reproductive trait on the dynamics of sexual conflict over mating/fertilization rate. Our model shows that an endosymbiont-induced alteration of a host female reproductive trait that affects mating rate can maintain the endosymbiont infection within the host population, and does so in the absence of sex-ratio distortion and cytoplasmic incompatibility.

The mitochondrial genome of Ruspolia dubia (Orthoptera: Conocephalidae) contains a short A+T-rich region of 70 bp in length

The complete sequence (14 971 bp) of the Ruspolia dubia mitochondrial genome was determined and annotated. The genome contains the gene content, base composition, and codon usage typical of metazoan mitochondrial genomes. All 37 genes are conserved in the positions observed most frequently in insect mitochondrial genome structures. The secondary structures of both small subunit and large subunit rRNA were predicted. The most unusual features found were the initiation codon (TTA) of COI and a short A+T-rich region of 70 bp in length. In addition, a short, highly conserved polythymidine stretch that was previously described in Orthoptera and Diptera was also present in the A+T-rich region.

Cytogenetics studies in thirteen brazilian species of Phaneropterinae (Orthoptera: Tettigonioidea: Tettigoniidae): main evolutive trends based on their karyological traits

The thirteen species of Phaneropterinae here studied can be arranged in four different groups according to their basic karyological traits. All of them share the same kind of chromosomal sex determining mechanism with X0 (male sign) and XX(female sign). The X chromosome differs among species and always appears heteropycnotic during prophase I, it is the largest in the set and segregates precociously during anaphase I. Among the species, the karyotypes varies in fundamental number between 31 to 21. The meaning of these significant changes in the karyotypes in relation to the phylogeny within some large taxonomic group of species is discussed.

The complete mitochondrial genome sequence of the Mormon cricket (Anabrus simplex: Tettigoniidae: Orthoptera) and an analysis of control region variability

The Anabrus simplex is a swarming plague orthopteran found in western North America. The genome is 15 766 bp in length and genome organization follows the ancestral insect gene arrangement. atp6 lacked any readily identifiable stop codon. Examination of mRNA secondary structure for this gene suggested a stem/loop-mediated mRNA post-transcriptional processing to liberate a mature atp6 mRNA with a complete stop codon produced by polyadenylation. Comparison of similar protein with protein gene boundaries in other insect species reveal a general mechanism for mRNA excision and provide further supporting evidence for post-transcriptional mRNA processing in mitochondrial genomes. The A + T-rich region, or control region, was sequenced for 55 A. simplex individuals from 12 different populations. Variance studies between these individuals show that the A + T-rich region contains significant phylogenetic signal to be used in population studies.

Understanding the genetic effects of recent habitat fragmentation in the context of evolutionary history: phylogeography and landscape genetics of a southern California endemic Jerusalem cricket (Orthoptera: Stenopelmatidae: Stenopelmatus)

Habitat loss and fragmentation due to urbanization are the most pervasive threats to biodiversity in southern California. Loss of habitat and fragmentation can lower migration rates and genetic connectivity among remaining populations of native species, reducing genetic variability and increasing extinction risk. However, it may be difficult to separate the effects of recent anthropogenic fragmentation from the genetic signature of prehistoric fragmentation due to previous natural geological and climatic changes. To address these challenges, we examined the phylogenetic and population genetic structure of a flightless insect endemic to cismontane southern California, Stenopelmatus'mahogani' (Orthoptera: Stenopelmatidae). Analyses of mitochondrial DNA sequence data suggest that diversification across southern California began during the Pleistocene, with most haplotypes currently restricted to a single population. Patterns of genetic divergence correlate with contemporary urbanization, even after correcting for (geographical information system) GIS-based reconstructions of fragmentation during the Pleistocene. Theoretical simulations confirm that contemporary patterns of genetic structure could be produced by recent urban fragmentation using biologically reasonable assumptions about model parameters. Diversity within populations was positively correlated with current fragment size, but not prehistoric fragment size, suggesting that the effects of increased drift following anthropogenic fragmentation are already being seen. Loss of genetic connectivity and diversity can hinder a population's ability to adapt to ecological perturbations commonly associated with urbanization, such as habitat degradation, climatic changes and introduced species. Consequently, our results underscore the importance of preserving and restoring landscape connectivity for long-term persistence of low vagility native species.

Molecular phylogeny of Banza (Orthoptera: Tettigoniidae), the endemic katydids of the Hawaiian Archipelago

The extant endemic katydids (Orthoptera: Tettigoniidae) of the Hawaiian Archipelago include one to three species per high island and a single species on Nihoa, all currently placed in the genus Banza. These acoustic insects provide an excellent opportunity for investigating the evolution of reproductive isolation and speciation, but such studies require an understanding of phylogenetic relationships within the group. We use maximum parsimony, likelihood-based Bayesian inference, and maximum likelihood to infer phylogenetic relationships among these taxa, based on approximately 2kb of mitochondrial cytochrome oxidase I and cytochrome b. Our results strongly support two distinct high island clades: one clade ("Clade I") composed of species from Kauai, Oahu, Molokai, and Lanai and another clade ("Clade II") composed of species from Maui and Hawaii (Banza unica, from Oahu, may be basal to both these clades, but its placement is not well resolved). Within these clades, some inferred relationships are strongly supported, such as the sister status of B. kauaiensis (Kauai) and B. parvula (Oahu) within Clade I, but other relationships remain more ambiguous, such as the relative position of B. brunnea (Maui) within Clade II. Although a detailed reconstruction of the historical biogeography of the Hawaiian katydids is difficult, we use our genetic data combined with the known geological history of the Hawaiian Islands to set limits on plausible historical scenarios for diversification of this group. Beyond these historical biogeographic inferences, our results indicate possible cryptic speciation on both Oahu and Hawaii, as well as what may be unusually high average rates of nucleotide substitution. The present work sets the stage for future genetic and experimental investigations of this group.

Phylogeny of the cricket subfamily Eneopterinae (Orthoptera, Grylloidea, Eneopteridae) based on four molecular loci and morphology

The phylogenetic relationships of 39 species of Eneopterinae crickets are reconstructed using four molecular markers (16S rRNA, 12S rRNA, cytochrome b, 18S rRNA) and a large morphological data set. Phylogenetic analysis via direct optimisation of DNA sequence data using parsimony as optimality criterion is done for six combinations of weighting parameter sets in a sensitivity analysis. The results are discussed in a twofold purpose: first, in term of significance of the molecular markers for phylogeny reconstruction in Ensifera, as our study represents the first molecular phylogeny performed for this insect suborder at this level of diversity; second, in term of corroboration of a previous phylogeny of Eneopterinae, built on morphological data alone. The four molecular markers all convey phylogenetic signal, although variously distributed on the tree. The monophyly of the subfamily, that of three over five tribes, and of 10 over 13 genera, are recovered. Finally, previous hypotheses on the evolution of acoustic devices and signals in the Eneopterinae clade are briefly tested, and supported, by our new data set.

Molecular phylogeography of Dolichopoda cave crickets (Orthoptera, Rhaphidophoridae): a scenario suggested by mitochondrial DNA

This study focuses on the phylogenetic relationships among a number of West-Mediterranean cave crickets species belonging to Dolichopoda; primarily a Mediterranean genus, distributed from eastern Pyrenees to Caucasus. In this paper, 11 Dolichopoda species from the French Pyrenees (D. linderi), the island of Corsica (D. bormansi and D. cyrnensis), and northern, central, and southern Italy (D. ligustica, D. schiavazzii, D. aegilion, D. baccettii, D. laetitiae, D. geniculata, D. capreensis, and D. palpata) were studied. Two more species, one from the Caucasus, D. euxina, and one from Greece, D. remyi, were also included in the analyses, together with more distant species within the same family to be used as outgroups. Fifteen hundred base pairs of mitochondrial DNA, corresponding to the small subunit of the ribosomal RNA (16S rRNA) and to the subunit I of the cytochrome oxidase I (COI), were sequenced in order to clarify the phylogenetic relationships and biogeography of this group of Mediterranean cave crickets. The molecular data are congruent with a phylogeographic pattern; with the geographically close species also the most related ones. Based on mtDNA divergence, the present-day distribution of genetic diversity seems to have been impacted by climatic events due to glacial and interglacial cycles that have characterized the Pleistocene era.

Phylogeny of Ensifera (Hexapoda: Orthoptera) using three ribosomal loci, with implications for the evolution of acoustic communication

Representatives of the Orthopteran suborder Ensifera (crickets, katydids, and related insects) are well known for acoustic signals produced in the contexts of courtship and mate recognition. We present a phylogenetic estimate of Ensifera for a sample of 51 taxonomically diverse exemplars, using sequences from 18S, 28S, and 16S rRNA. The results support a monophyletic Ensifera, monophyly of most ensiferan families, and the superfamily Gryllacridoidea which would include Stenopelmatidae, Anostostomatidae, Gryllacrididae, and Lezina. Schizodactylidae was recovered as the sister lineage to Grylloidea, and both Rhaphidophoridae and Tettigoniidae were found to be more closely related to Grylloidea than has been suggested by prior studies. The ambidextrously stridulating haglid Cyphoderris was found to be basal (or sister) to a clade that contains both Grylloidea and Tettigoniidae. Tree comparison tests with the concatenated molecular data found our phylogeny to be significantly better at explaining our data than three recent phylogenetic hypotheses based on morphological characters. A high degree of conflict exists between the molecular and morphological data, possibly indicating that much homoplasy is present in Ensifera, particularly in acoustic structures. In contrast to prior evolutionary hypotheses based on most parsimonious ancestral state reconstructions, we propose that tegminal stridulation and tibial tympana are ancestral to Ensifera and were lost multiple times, especially within the Gryllidae.

Molecular cytogenetic characterization and chromosomal distribution of the satellite DNA in the genome of Oxya hyla intricata (Orthoptera: Catantopidae)

The genomic DNA of the grasshopper (Oxya hyla intricata) was subjected to electrophoresis after digestion with HaeIII, and the result showed two bands of highly repetitive DNA, approximately 200 and 400 bp in length. The 200-bp HaeIII-digested fragment was cloned and characterized by sequencing and fluorescence in situ hybridization (FISH). The results showed the presence of two distinct satellite DNA (stDNA) families: one consisting of a 169-bp repeated element having an A+T content of 60.9% and the other consisting of a 204-bp repeated element having an A+T content of 53.9%. No significant homology between the two stDNA families was observed. FISH showed that the chromosomal locations of these families are different from each other. The 169-bp element was located in the C-band-positive regions of the short arms of most of the chromosomes, whereas the 204-bp element was located in the centromeric regions of three chromosome pairs. These results imply that the origins of these two DNA families are different. The results of zoo-blot hybridization to the genomic DNA from four Oxya species, O. hyla intricata, O. japonica japonica, O. chinensis formosana, and O. yezoensis, suggest that the two stDNA families found in the present study are species-specific for O. hyla intricata.

Are solitary and gregarious Mormon crickets (Anabrus simplex, Orthoptera, Tettigoniidae) genetically distinct?

Phase polyphenisms are usually thought to reflect plastic responses of species, independent of genetic differences; however, phase differences could correlate with genetic differentiation for various reasons. Mormon crickets appear to occur in two phases that differ in morphology and behaviour. Solitary individuals are cryptic and sedentary whereas gregarious individuals form bands, migrate, and are aposematically coloured. These traits have been thought to be phenotypically plastic and induced by environmental conditions. However, there has been no previous investigation of the extent of genetic differences between solitary and gregarious populations of this widespread North American species. We sequenced two mitochondrial genes, COII and COIII, in samples of Mormon crickets from gregarious populations west of the continental divide and solitary mountain populations primarily east of the divide. Sequencing revealed two genetically distinct clades that broadly correspond with the solitary eastern populations and the mainly gregarious western populations. We used coalescent modelling to test the hypothesis that the species consists of two deep genetic clades, as opposed to a series of equally distinct populations. Results allowed us to reject the null hypothesis that a radiation independent of phase produced these clades, and molecular clock estimates indicate the time of divergence to be approximately 2 million years ago. This work establishes that the solitary populations found in the mountains on the eastern slope are part of a clade that is genetically distinct from the western populations, which are primarily gregarious, and the implications of this apparent correlation between phase and genetic differentiation are discussed.

[Chromosomal C-banding karyotype of 2 species of genus Asiotmethis (Acridoidea:Pamphagidae) from China]

The chromosomal C-banding karyotype in the spermatogenesis of 2 species of Genus Asiotmethis, Uvarov 1943 from China were investigated. It was found that the diploid chromosome number of Asiotmethis zacharjini (Bei-Bienko, 1926) was 2n (male) =18, the neo-X was a submetacentric chromosome and the rest were acrocentric chromosomes. C-banding pattern showed that all chromosomes presented a paracentromeric block, an interstitial C-band near the centrometic C-block and additional C-band in the distal region. And, the mechanism for sex determination lay in neo-XY (male). In Asiotmethis jubatus (Uvarov, 1926), the diploid chromosome number was 2n (male) =19. All autosomes and X-chromosomes were acrocentric with paracentromeric C-band only, and the mechanism for sex determination lay in XO (male). The difference in heterochromatin content between the 2 species was significant at 0.05 level.

Telomeric and interstitial telomeric-like DNA sequences in Orthoptera genomes

A (TTAGG)n-specific telomeric DNA probe was hybridized to 11 orthopteroid insect genomes by fluorescence in situ hybridization. Nine different genera, mainly distributed within two evolutionary branches with male chromosome numbers 2n = 23 and 2n = 17 were included in the analysis. Telomere sequences yielded positive signals in every telomere and there was a considerable number of interstitial telomeric-like sequences, mainly located at the distal end of some, but not all, subterminal chromosome regions. One of the species, Pyrgomorpha conica, showed massive hybridization signals associated with constitutive heterochromatin. The results are discussed along two lines: (i) the chromosomal evolutionary trends within this group of insects and (ii) the putative role that ITs may play in a genome when they are considered telomere-derived, but not telomere-functional, DNA sequences.

Heavy metal accumulation, heat shock protein expression and cytogenetic changes in Tetrix tenuicornis (L.) (Tetrigidae, Orthoptera) from polluted areas

The orthopteran insect Tetrix tenuicornis, collected from polluted and unpolluted areas, was used to study heavy metal accumulation and its impact on stress protein levels and on changes in the number and morphology of chromosomes in mitotic and meiotic cells. During two consecutive years, insects were collected from polluted areas of zinc-lead mine spoils near Bolesław (Poland) and from unpolluted areas near Busko and Staszów (Poland). T. tenuicornis from the polluted area showed 1.5, 4.03, 4.32 and 41.73 times higher concentrations of copper (Cu), zinc (Zn), lead (Pb) and cadmium (Cd), respectively, than insects of the same species collected from unpolluted areas. Insects exposed to heavy metals showed only small changes, and rather a decrease in the concentration of constitutive and inducible heat shock proteins Hsp70, the level of which increases under stress conditions. A cytogenetic study of T. tenuicornis revealed intra-population anomalies in chromosome number and morphology in mitotic and meiotic cells and the presence of an additional B chromosome in germinal cells. In 50% of females collected from polluted areas, mosaic oogonial mitotic chromosome sets and diploid, hypo- or hypertetraploid, tetraploid, and octoploid chromosome numbers were detected. In turn, 14.6% of males showed a heterozygous deficiency of chromatin in L2 and M3 bivalents in addition to the presence of B chromosomes.

Chromosomal polymorphism, morphometric traits and mating success in Leptysma argentina Bruner (Orthoptera)

The South-American species Leptysma argentina Bruner is polymorphic for a centric fusion between chromosomal pairs 3 and 6 (fusion 3/6). Cytogenetic and morphological studies revealed that fusion 3/6 significantly increases some morphometric variables in males. A selection components study showed that the fusion is positively selected for longevity, the direct effect being exerted on thorax height. Moreover, a unisexual approach revealed that sexual male selection acts by increasing third femur length. In the present study the effect of fusion 3/6 on morphometric variables and the effect of body size and karyotype on mating success in both males and females were analysed through a bisexual approach. Total body length (TL) and third femur length (FL) were significantly larger amongst the fusion carrier females. Besides, the largest females and the carriers of the fusion have increased mating success. The selection differential suggests that directional sexual selection favours the females with increased TL and fusion dosage; however, the selection gradient revealed that none of the variables here analysed is a direct target of sexual selection. The male sexual selection study agrees with previous results, showing the importance of the third pair of legs in male mating success among grasshoppers.

Inversion polymorphisms and natural selection in Trimerotropis pallidipennis (Orthoptera)

Grasshoppers have been much less studied than Drosophila when it comes to inversion polymorphisms, despite the occurrence of this rearrangement in several species of grasshoppers. In the present study, 354 males from a natural population of the New World species Trimerotropis pallidipennis, polymorphic for 6 pericentric inversions in 4 chromosome pairs, were sampled at the beginning and at the end of the adult life span. This sampling, along with the fact that generations in this grasshopper are annual and discrete, was done to detect differential adult male longevity among karyotypes and departures from formal null models, such as gametic phase equilibrium. These methods allow the detection of natural selection taking place in the wild. The comparison between age classes showed that some inversions were significantly more frequent in one sample, thus revealing the operation of natural selection. Gametic phase disequilibrium was detected in the sample of aged males but not in the sample of young ones. Furthermore, here we aim to detect the phenotypic targets of longevity selection by examining morphometric characters, in order to have a clearer idea of the relation between inversions and natural selection in this species. These results corroborate previous studies that suggested that the inversions are involved in natural selection, and an adaptive model has been proposed for the pattern of inversion frequencies throughout several populations at different altitudes and latitudes.

[Genetic relationships among five populations of Oxya chinensis in Shanxi Province and adjacent region based on RAPD]

Random Amplified Polymorphic DNA (RAPD) markers were applied to analyze genetic relationships of five populations of Oxya chinensis collected from Shanxi Province and laner Mongolia, Oxya japonica from Guangxi was used as an outgroup. Genomic DNA of sixty-four individuals was extracted from dissected leg muscle using phenol-chloroform procedure, and then amplified by 10 random primers (10 bp), the amplified products were separated by agarose gel electrophoresis. The results were as follows: (1) a total of 115 clear and reproducible bands were generated, molecular size was 200 - 2500 bp. The obtaining segments of individual primer were among 5 - 15, on average, about 12 bands per primer. (2) The dendrogram based on 115 RAPD markers was constructed and clustered using between-groups linkage method. The cluster analysis indicated strong similarities within populations, firstly, the individuals in each population closely clustered together;and then five populations of Oxya chinensis could be distinguished with RAPD markers and were grouped into two distinct clusters. The dendrogram showed that Shanxi Linyi population and Tunliu population were the most similar,which were clustered with Taiyuan population Shanxi into one cluster, while, Daixian population in Shanxi was closely related to laner Mongolia population, both of which belonged to the other cluster. Nevertheless, All the five populations of Oxya chinensis had far genetic distance with Oxya japonica. In the dendrogram, a tendency of clustering following a North-South gradient could be observed, the results implied that genetic distance of five populations of Oxya chinensis correlated with geographical distance to some degree.