The exoskeleton of the female genitalic region in Petrobiellus takunagae (Insecta: Archaeognatha): Insect-wide terminology,homologies, and functional interpretations

The exoskeleton of the female genitalic region (abdominal venters 7–9) in Petrobiellus takunagae (Machilidae-Petrobiellinae) is studied using light microscopy and SEM. Sclerites are distinguished from membrane by the degree of cuticular flexibility. However, the microsculpture of the cuticle is shown to be useful in characterising the heterogeneity of the cuticle and in detecting weak sclerotisations. The morphology of Petrobiellus is compared with that in Trigoniophthalmus alternatus (Machilidae-Machilinae) described previously. While venter 7 is similar, venters 8 and 9 show many differences in the presence/absence or fusion/separation of particular sclerites. This suggests female genitalic morphology to be a valuable character system for phylogenetic and taxonomic work in Archaeognatha. Comparison with other insect orders is aimed at detecting homologous structures and conditions. Important points are: (1) Petrobiellus has a sclerotised genital lobe posteriorly on venter 7, similar to Zygentoma and Dictyoptera; it bears the gonopore. (2) Petrobiellus has a posterior sclerite on venter 9 that is very similar to a sclerite of Odonata. (3) The morphology of the coxal lobes of venter 9 (gonoplacs) suggests their function as a sheath of the ovipositor. From female genitalic morphology we deduce the process of oviposition, describing an external egg transportation tract.     

Immunohistochemical investigation of locust neuroparsin-like substances in several insects,in some other invertebrates,and vertebrates

Summary Anti-neuroparsin serum was immunohistochemically tested on brain and/or neurohemal organ from 40 insect species belonging to 13 orders, and from 8 non-insect invertebrate and 5 vertebrate representatives using the peroxidase-antiperoxidase procedure. In insects, immunostaining of only the A1 type of the protocerebral median neurosecretory cells was revealed in all species tested of Odonata. Dictyoptera, Isoptera and Orthoptera and in 2 species from the 9 other orders out of 13 orders tested. No immunostaining was detected in vertebrate and non-insect invertebrate species except in 2 annelid species out of 4 tested. The distribution of neuroparsin-like products in Coelomata appears to be restricted mainly to 4 phylogenetically close insect orders.     

Complete Mitochondrial Genome of the Free-Living Earwig, Challia fletcheri (Dermaptera: Pygidicranidae) and Phylogeny of Polyneoptera

The insect order Dermaptera, belonging to Polyneoptera, includes ～2,000 extant species, but no dermapteran mitochondrial genome has been sequenced. We sequenced the complete mitochondrial genome of the free-living earwig, Challia fletcheri, compared its genomic features to other available mitochondrial sequences from polyneopterous insects. In addition, the Dermaptera, together with the other known polyneopteran mitochondrial genome sequences (protein coding, ribosomal RNA, and transfer RNA genes), were employed to understand the phylogeny of Polyneoptera, one of the least resolved insect phylogenies, with emphasis on the placement of Dermaptera. The complete mitochondrial genome of C. fletcheri presents the following several unusual features: the longest size in insects is 20,456 bp; it harbors the largest tandem repeat units (TRU) among insects; it displays T- and G-skewness on the major strand and A- and C-skewness on the minor strand, which is a reversal of the general pattern found in most insect mitochondrial genomes, and it possesses a unique gene arrangement characterized by a series of gene translocations and/or inversions. The reversal pattern of skewness is explained in terms of inversion of replication origin. All phylogenetic analyses consistently placed Dermaptera as the sister to Plecoptera, leaving them as the most basal lineage of Polyneoptera or sister to Ephemeroptera, and placed Odonata consistently as the most basal lineage of the Pterygota.     

Immunohistochemical investigation of locust neuroparsin-like substances in several insects, in some other invertebrates, and vertebrates

Anti-neuroparsin serum was immunohistochemically tested on brain and/or neurohemal organ from 40 insect species belonging to 13 orders, and from 8 non-insect invertebrate and 5 vertebrate representatives using the peroxidase-antiperoxidase procedure. In insects, immunostaining of only the A1 type of the protocerebral median neurosecretory cells was revealed in all species tested of Odonata, Dictyoptera, Isoptera and Orthoptera and in 2 species from the 9 other orders out of 13 orders tested. No immunostaining was detected in vertebrate and non-insect invertebrate species except in 2 annelid species out of 4 tested. The distribution of neuroparsin-like products in Coelomata appears to be restricted mainly to 4 phylogenetically close insect orders.     

Possible Removal of Rival Sperm by the Elongated Genitalia of the Earwig, Euborellia plebeja

Sperm displacement is a sperm competition avoidance mechanism that reduces the paternity of males that have already mated with the female. Direct anatomical sperm removal or sperm flushing is known to occur in four insect orders: Odonata, Orthoptera, Coleoptera and Hymenoptera. In a fifth order, Dermaptera (earwigs), I found that the virga (the elongated rod of the male genitalia) of Euborellia plebeja seems to be used to remove rival sperm from the spermatheca (a fine-tubed female sperm storage organ). In this species, copulation lasted on average 4.6 minutes, during which time the male inserted the virga deep into the spermatheca, and then extracted it ejaculating semen from the opening of the virgal tip. The extraction of virgae (with its brim-like tip) appeared to cause removal of stored sperm in the spermatheca. The virga was as long as the body length of males, and the spermatheca was twice the female body length. The long length of the spermatheca and the possible removal function of the virga may select for virgal elongation.     

Mantophasmatodea and phylogeny of the lower neopterous insects

Polyneoptera is a name sometimes applied to an assemblage of 11 insect orders comprising the lower neopterous or “orthopteroid” insects. These orders include familiar insects such as Orthoptera (grasshoppers), Blattodea (roaches), Isoptera (termites) (Mantodea) praying mantises, Dermaptera (earwigs), Phasmatodea (stick insects), Plecoptera (stoneflies), as well as the more obscure, Embiidina (web‐spinners), Zoraptera (angel insects) and Grylloblattodea (ice‐crawlers). Many of these insect orders exhibit a high degree of morphological specialization, a condition that has led to multiple phylogenetic hypotheses and little consensus among investigators. We present a phylogenetic analysis of the polyneopteran orders representing a broad range of their phylogenetic diversity and including the recently described Mantophasmatodea. These analyses are based on complete 18S rDNA, 28S rDNA, Histone 3 DNA sequences, and a previously published morphology matrix coded at the ordinal level. Extensive analyses utilizing different alignment methodologies and parameter values across a majority of possible ranges were employed to test for sensitivity of the results to ribosomal alignment and to explore patterns across the theoretical alignment landscape. Multiple methodologies support the paraphyly of Polyneoptera, the monophyly of Dictyoptera, Orthopteroidea (sensu Kukalova‐Peck; i.e. Orthoptera + Phasmatodea + Embiidina), and a group composed of Plecoptera + Dermaptera + Zoraptera. Sister taxon relationships between Embiidina + Phasmatodea in a group called “Eukinolabia”, and Dermaptera + Zoraptera (“Haplocercata”) are also supported by multiple analyses. This analysis also supports a sister taxon relationship between the newly described Mantophasmatodea, which are endemic to arid portions of southern Africa, and Grylloblattodea, a small order of cryophilic insects confined to the north‐western Americas and north‐eastern Asia, in a group termed “Xenonomia”. This placement, coupled with the morphological disparity of the two groups, validates the ordinal status of Mantophasmatodea. © The Willi Hennig Society 2005.     

The evolution of asymmetric genitalia in spiders and insects

Asymmetries are a pervading phenomenon in otherwise bilaterally symmetric organisms and recent studies have highlighted their potential impact on our understanding of fundamental evolutionary processes like the evolution of development and the selection for morphological novelties caused by behavioural changes. One character system that is particularly promising in this respect is animal genitalia because (1) asymmetries in genitalia have evolved many times convergently, and (2) the taxonomic literature provides a tremendous amount of comparative data on these organs. This review is an attempt to focus attention on this promising but neglected topic by summarizing what we know about insect genital asymmetries, and by contrasting this with the situation in spiders, a group in which genital asymmetries are rare. In spiders, only four independent origins of genital asymmetry are known, two in Theridiidae (Tidarren/Echinotheridion, Asygyna) and two in Pholcidae (Metagonia, Kaliana). In insects, on the other hand, genital asymmetry is a widespread and common phenomenon. In some insect orders or superorders, genital asymmetry is in the groundplan (e.g. Dictyoptera, Embiidina, Phasmatodea), in others it has evolved multiple times convergently (e.g. Coleoptera, Diptera, Heteroptera, Lepidoptera). Surprisingly, the huge but widely scattered information has not been reviewed for over 70 years. We combine data from studies on taxonomy, mating behaviour, genital mechanics, and phylogeny, to explain why genital asymmetry is so common in insects but so rare in spiders. We identify further fundamental differences between spider and insect genital asymmetries: (1) in most spiders, the direction of asymmetry is random, in most insects it is fixed; (2) in most spiders, asymmetry evolved first (or only) in the female while in insects genital asymmetry is overwhelmingly limited to the male. We thus propose that sexual selection has played a crucial role in the evolution of insect genital asymmetry, via a route that is accessible to insects but not to spiders. The centerpiece in this insect route to asymmetry is changes in mating position. Available evidence strongly suggests that the plesiomorphic neopteran mating position is a female-above position. Changes to male-dominated positions have occurred frequently, and some of the resulting positions require abdominal twisting, flexing, and asymmetric contact between male and female genitalia. Insects with their median unpaired sperm transfer organ may adopt a one-sided asymmetric position and still transfer the whole amount of sperm. Spiders with their paired sperm transfer organs can only mate in symmetrical or alternating two-sided positions without foregoing transfer of half of their sperm. We propose several hypotheses regarding the evolution of genital asymmetry. One explains morphological asymmetry as a mechanical compensation for evolutionary and behavioural changes of mating position. The morphological asymmetry per se is not advantageous, but rather the newly adopted mating position is. The second hypothesis predicts a split of functions between right and left sides. In contrast to the previous hypothesis, morphological asymmetry per se is advantageous. A third hypothesis evokes internal space constraints that favour asymmetric placement and morphology of internal organs and may secondarily affect the genitalia. Further hypotheses appear supported by a few exceptional cases only.     

Phylogenetic relationships among insect orders based on three nuclear protein-coding gene sequences

Many attempts to resolve the phylogenetic relationships of higher groups of insects have been made based on both morphological and molecular evidence; nonetheless, most of the interordinal relationships of insects remain unclear or are controversial. As a new approach, in this study we sequenced three nuclear genes encoding the catalytic subunit of DNA polymerase delta and the two largest subunits of RNA polymerase II from all insect orders. The predicted amino acid sequences (In total, approx. 3500 amino acid sites) of these proteins were subjected to phylogenetic analyses based on the maximum likelihood and Bayesian analysis methods with various models. The resulting trees strongly support the monophyly of Palaeoptera, Neoptera, Polyneoptera, and Holometabola, while within Polyneoptera, the groupings of Isoptera/"Blattaria"/Mantodea (Superorder Dictyoptera), Dictyoptera/Zoraptera, Dermaptera/Plecoptera, Mantophasmatodea/Grylloblattodea, and Embioptera/Phasmatodea are supported. Although Paraneoptera is not supported as a monophyletic group, the grouping of Phthiraptera/Psocoptera is robustly supported. The interordinal relationships within Holometabola are well resolved and strongly supported that the order Hymenoptera is the sister lineage to all other holometabolous insects. The other orders of Holometabola are separated into two large groups, and the interordinal relationships of each group are (((Siphonaptera, Mecoptera), Diptera), (Trichoptera, Lepidoptera)) and ((Coleoptera, Strepsiptera), (Neuroptera, Raphidioptera, Megaloptera)). The sister relationship between Strepsiptera and Diptera are significantly rejected by all the statistical tests (AU, KH and wSH), while the affinity between Hymenoptera and Mecopterida are significantly rejected only by AU and KH tests. Our results show that the use of amino acid sequences of these three nuclear genes is an effective approach for resolving the relationships of higher groups of insects.     

The structure of the cereal sensory system and ventral nerve cord of Grylloblatta

Summary The structure of cereal sensilla, the cereal nerve and the central projections of the cereal sensory nerve of a notopteran (Grylloblatta sp.) are described and compared with other orthopteroid insects in which the cereal sensory system and central connections are well known. The cereal sensilla are similar to those of gryllids and blattids, but the gross structure of the cerci and distribution of cereal sensilla more closely resemble those of the Thysanura. The elements of the cereal sensory nerves and the central nervous system are similar to those of other orthopteroid insects, but extracellular material is present in greater quantity, and more extensive glial bundling of axons occurs in both the cereal nerve and central connectives. Glial structure, extracellular material and large multicristate mitochondria may be adaptations to life near 0° C. The form of central projections of the cereal nerve and the configuration of the largest abdominal interneurons are unlike those of gryllids and Dictyoptera; they are similar to those of Dermaptera.     

Ovoviviparity and genital evolution: a lesson from an earwig species with coercive traumatic mating and accidental breakage of elongated intromittent organs

Ovoviviparity or viviparity has evolved independently in animals and involves adaptations in females to accommodate developing embryos for a prolonged duration in their bodies, a condition which has likely to have influenced the evolution of the male genitalia. We aimed to ascertain whether the elongated male genitalia of the ovoviviparous free‐living earwig species Marava arachidis (Dermaptera: Spongiphoridae) delivers sperm directly to the female ovaries where fertilization occurs. Males mated coercively with females by grabbing the female antenna with their mouth parts. Although females resisted the mating attempts, pairs mated 3.3 times on average over 15 h. The elongated intromittent organ, known as a virga, was inserted into the long‐tubed spermatheca during insemination. Surgical ectomy of the spermatheca confirmed that sperm migrated from here to the ovaries with a variable delay. A pair of sclerites in the male genitalia frequently inflicted wounds near the spermathecal opening, while the single, thin virga sometimes broke off during mating. However, unlike earwigs bearing a ‘spare’ virga, damage was restricted to the tip of the virga, without which the males could still inseminate the females. We discuss the evolution of the genitalia in this insect in the light of sexual selection and sexual conflict over mating and fertilization.     

The tentorium and anterior head sulci in Dictyoptera and Mantophasmatodea (Insecta)

The tentorium, the anterior sulci of the head capsule (epistomal, subgenal, subantennal, circumantennal, and circumocular sulci), and the extension of the anterior tentorial pit were studied in 26 species of Blattaria (representing most principal lineages), 4 species of Mantodea (including the basal Mantoida schraderi), and 1 species each of Isoptera (the basal Mastotermes darwiniensis) and Mantophasmatodea (Austrophasma caledonense). The morphology of these head structures is compared with literature data on other insect orders, mainly Phasmatodea, Orthoptera, Dermaptera, Embioptera, and Plecoptera, and partly Odonata and Zygentoma. Characters are defined, presented in a matrix, and evaluated with regard to phylogenetic implications and homoplastic evolution. The structural relationships of the subantennal sulcus to the subgenal, circumocular, and circumantennal sulci, which are highly variable and strongly homoplastic (depending much on the size of the compound eyes) are a focal issue; several types of subantennal sulci are defined. The presence of an anterior transverse bridge in the tentorium (“perforated tentorium”) of all Dictyoptera here studied confirms the monophyly of this group. Mantophasmatodea lacks this element.     

The structure of condensed chromosomes in mitosis and meiosis of insects

This article revolves around the structure of condensed mitotic and meiotic chromosomes in insects. In the first section, the potential of cytological approaches in the field of chromosome biology is described. Emphasis is on immunolabeling, and transmission and scanning electron microscopy. In particular, the latter technology revealed a series of unusual components in association with the chromosomes, such as membranes and non-chromatin material, which is presumably responsible for the formation of achiasmatic bivalents. Virus-like particles were found scattered throughout the chromatin in a Lepidoptera species. This association is possibly responsible for the transmission of the particles into the next generation. Then, the cytology and the molecular make-up of the key components of insect chromosomes are described. These are the centromeres, telomeres, and nucleoli. In any case, the situation in insects is compared briefly with that in mammals. The general structure of the centromeres in terms of centromere-specific repetitive DNA and proteins is similar in insects and mammals. This applies also to telomeres of most insect orders, but the chromosome ends of Diptera species differ from those in mammals. Fine structure observations raise also the possibility that insect nucleoli have a specific architecture. Chromosomal proteins—and emphasis is on histone acetylation—are addressed in an individual section. Evidence is accumulating that histone H4 acetylation plays a role in dosage compensation and is a cytogenetic marker of constitutive heterochromatin in insects. In the final section, the characteristics of holokinetic chromosomes are listed. A series of insect orders, where direct or indirect evidence points to chromosomes with relatively large centromeres, is presented. These are Lepidoptera, Trichoptera, Hemiptera, Homoptera, Odonata, and Dermaptera.     

The function and evolution of male and female genitalia in Phyllophaga Harris scarab beetles (Coleoptera: Scarabaeidae)

Genitalia diversity in insects continues to fuel investigation of the function and evolution of these dynamic structures. Whereas most studies have focused on variation in male genitalia, an increasing number of studies on female genitalia have uncovered comparable diversity among females, but often at a much finer morphological scale. In this study, we analysed the function and evolution of male and female genitalia in Phyllophaga scarab beetles, a group in which both sexes exhibit genitalic diversity. To document the interaction between male and female structures during mating, we dissected flash‐frozen mating pairs from three Phyllophaga species and investigated fine‐scale morphology using SEM. We then reconstructed ancestral character states using a species tree inferred from mitochondrial and nuclear loci to elucidate and compare the evolutionary history of male and female genitalia. Our dissections revealed an interlocking mechanism of the female pubic process and male parameres that appears to improve the mechanical fit of the copulatory position. The comparative analyses, however, did not support coevolution of male and female structures and showed more erratic evolution of the female genitalia relative to males. By studying a group that exhibits obvious female genitalic diversity, we were able to demonstrate the relevance of female reproductive morphology in studies of male genital diversity.     

广东南岭国家级自然保护区大东山昆虫名录(Ⅰ)

报道广东南岭国家级自然保护区大东山管理站所辖林区蜻蜓目、蜚蠊目、螳螂目、等翅目、竹节虫目、直翅目和革翅目等7目昆虫名录,计有53科169属253种,其中蜻蜓目1种、竹节虫目8种、直翅目1种为本研究发现的新种。     

Phylogeny of earwigs (Insecta: Dermaptera) based on molecular and morphological evidence: reconsidering the classification of Dermaptera

Abstract. Dermaptera (earwigs) is a cosmopolitan order of insects, the phylogenetic relationships of which are poorly understood. The phylogeny of Dermaptera was inferred from large subunit ribosomal (28S), small subunit ribosomal (18S), histone-3 (H3) nuclear DNA sequences, and forty-three morphological characters. Sequence data were collected for thirty-two earwig exemplar taxa representing eight families in two suborders: Hemimeridae (suborder Hemimerina); Pygidicranidae, Anisolabididae, Labiduridae, Apachyidae, Spongiphoridae, Chelisochidae and Forficulidae (suborder Forficulina). Eighteen taxa from ten additional orders were also included, representing Ephemeroptera, Odonata, Orthoptera, Phasmida, Embiidina, Mantodea, Isoptera, Blattaria, Grylloblattodea and Zoraptera. These data were analysed via direct optimization in poy under a range of gap and substitution values to test the sensitivity of the data to variations in parameter values. These results indicate that the epizoic Hemimerus is not sister to the remaining Dermaptera, but rather nested as sister to Forficulidae + Chelisochidae. These analyses support the paraphyly of Pygidicranidae and Spongiphoridae and the monophyly of Chelisochidae, Forficulidae, Anisolabididae and Labiduridae.     

The food of the Afrotropical nightjars

Jackson, H.D. 2000. The food of the Afrotrapical nightjars. Ostrich 71(3&4): 408-415. A synthesis of 722 published and unpublished records of nightjar stomach contents from Afrotropical specimens was undertaken. Coleoptera were found in 84.6% of the stomachs, often in substantial numbers, beetles providing these birds with their staple diet. Lepidoptera occurred in 34.9% of the stomachs and were often present in large numbers; moths are an extremely important part of the nightjar diet in the Afrotropics, especially during winter. Orthoptera, Hemiptera and Dictyoptera, although present in 24.7, 16.3 and 11.5% of the stomachs, respectively, usually occurred in rather small numbers. Hymenoptera and lsoptera were often present in great numbers, yet were found in only 10.4 and 10.1% of the stomachs, respectively, so a limited number of individual nightjars had found emerging swarms of alate ants or termites in season. Neuroptera, Diptera, Odonata and Dermaptera were found in a few stomachs (2.4, 1.2, 0.6 and 0.3%, respectively) but these insects clearly play a very small part in the diet of nightjars in the Afrotropics. Similarities and differences in diet between some closely related nightjar species are discussed. Grit was found in 16 stomachs only, so deliberate ingestion of stones to aid digestion is regarded as extremely unlikely among nightjars in the Afrotropics. The contents of a full stomach may account for as much as 20-25% of the body mass of a nightjar.     

A Unique Box in 28S rRNA Is Shared by the Enigmatic Insect Order Zoraptera and Dictyoptera

The position of the Zoraptera remains one of the most challenging and uncertain concerns in ordinal-level phylogenies of the insects. Zoraptera have been viewed as having a close relationship with five different groups of Polyneoptera, or as being allied to the Paraneoptera or even Holometabola. Although rDNAs have been widely used in phylogenetic studies of insects, the application of the complete 28S rDNA are still scattered in only a few orders. In this study, a secondary structure model of the complete 28S rRNAs of insects was reconstructed based on all orders of Insecta. It was found that one length-variable region, D3-4, is particularly distinctive. The length and/or sequence of D3-4 is conservative within each order of Polyneoptera, but it can be divided into two types between the different orders of the supercohort, of which the enigmatic order Zoraptera and Dictyoptera share one type, while the remaining orders of Polyneoptera share the other. Additionally, independent evidence from phylogenetic results support the clade (Zoraptera+Dictyoptera) as well. Thus, the similarity of D3-4 between Zoraptera and Dictyoptera can serve as potentially valuable autapomorphy or synapomorphy in phylogeny reconstruction. The clades of (Plecoptera+Dermaptera) and ((Grylloblattodea+Mantophasmatodea)+(Embiodea+Phasmatodea)) were also recovered in the phylogenetic study. In addition, considering the other studies based on rDNAs, this study reached the highest congruence with previous phylogenetic studies of Holometabola based on nuclear protein coding genes or morphology characters. Future comparative studies of secondary structures across deep divergences and additional taxa are likely to reveal conserved patterns, structures and motifs that can provide support for major phylogenetic lineages.     

Intersex is required for female sexual development in Hermetia illucens

Sex-determination pathways are extremely diverse. Understanding the mechanism of sex determination in insects is important for genetic manipulation of the pest population and for breeding of economically valuable insects. Although sex determination has been well characterized in the model species Drosophila melanogaster, little is known about this pathway in Stratiomyidae. In the present study, we first identified the Drosophila intersex (ix) homolog in Hermetia illucens, also known as the black soldier fly, which belongs to the Stratiomyidae family and which is an important insect for the conversion of various organic wastes. Phylogenetic analyses and multiple sequence alignment revealed that Hiix is conserved compared with Drosophila. We showed that Hiix is highly expressed in internal genitalia. Disruption of the Hiix gene using CRISPR/Cas9 resulted in female-specific defects in external genitalia and abnormal and undersized ovaries. Taken together, our study furthers our understanding of sex determination in insects and could facilitate breeding of H. illucens.     

Unlocking the "Black box": internal female genitalia in Sepsidae (Diptera) evolve fast and are species-specific

Background  

The species-specificity of male genitalia has been well documented in many insect groups and sexual selection has been proposed as the evolutionary force driving the often rapid, morphological divergence. The internal female genitalia, in sharp contrast, remain poorly studied. Here, we present the first comparative study of the internal reproductive system of Sepsidae. We test the species-specificity of the female genitalia by comparing recently diverged sister taxa. We also compare the rate of change in female morphological characters with the rate of fast-evolving, molecular and behavioral characters.