Insect Order Mantophasmatodea Research Articles

Asymmetry of the male internal reproductive organs in Mantophasmatodea

BackgroundAsymmetries are a widespread phenomenon in otherwise bilaterally symmetric organisms, and investigation of asymmetric structures can help us gather insights into fundamental evolutionary processes such as the selection for morphological novelties caused by behavioural changes. In insects, asymmetric genitalia have evolved in almost every order, and usually it’s the sclerotized parts and most conspicuous male phallic organs that are known to exhibit asymmetries. While external copulatory organs in insects have often been subject to investigations concerning asymmetries and the evolution thereof, internal reproductive structures have received far less attention. Here we describe the internal and external male genitalia in three species of Austrophasmatidae, Mantophasmatodea, using μ-CT imaging and light microscopy. Mantophasmatodea is the most recently discovered insect order, and with 21 species described to date, it is among the smallest insect orders currently known.ResultsWe confirm that male heelwalkers exhibit asymmetries in the external genitalia and associated structures, represented by asymmetric phallic lobes and cerci. Moreover, we found an extreme asymmetry within the internal male genitalia: in all adult males investigated (N = 5), the seminal vesicle, a dilatation of the vas deferens, was only developed on the right side of the male while missing on the left side.ConclusionThe false-male-above mating position exhibited by Mantophasmatodea and especially the long copulation duration of ca. 3 days might select for this unusual absence asymmetry of the left seminal vesicle. If this holds true for all heelwalker species, this absence asymmetry constitutes another autapomorphy for Austrophasmatidae or even the insect order Mantophasmatodea.

Variable Molecular Markers for the Order Mantophasmatodea (Insecta).

The recently discovered insect order Mantophasmatodea currently comprises 19 Southern African species. These mainly occur in allopatry, have high levels of color polymorphism and communicate via species- and gender-specific vibratory signals. High levels of interspecific morphological conservatism mean that cryptic species are likely to be uncovered. These aspects of Mantophasmatodean biology make them an ideal group in which to investigate population divergence due to habitat-specific adaptation, sexual selection, and potentially sensory speciation. Lack of appropriate genetic markers has thus far rendered such studies unfeasible. To address this need, the first microsatellite loci for this order were developed. Fifty polymorphic loci were designed specifically for Karoophasma biedouwense (Austrophasmatidae), out of which 23 were labeled and tested for amplification across the order using 2-3 individuals from 10 species, representing all 4 currently known families. A Bayesian mitochondrially encoded cytochrome c oxidase I (COI) topology was reconstructed and divergence dates within the order were estimated for the first time. Amplification success and levels of polymorphism were compared with genetic divergence and time since divergence. In agreement with studies on vertebrate taxa, both amplification and variability were negatively correlated with distance (temporal and genetic). The high number of informative loci will offer sufficient resolution for both broad level population genetic analysis and individual based pedigree or parentage analyses for most species in Austrophasmatidae, with at least some loci available for the other families. This resource will facilitate research into the evolutionary biology of this understudied but fascinating group.

Biodiversity, ecology, and behavior of the recently discovered insect order Mantophasmatodea

The spectacular discovery of the new insect order Mantophasmatodea in 2002 was immediately followed by detailed studies on morphology and scattered information on different aspects of its behavior and general biology. A distinct feature of these predatory insects is the development of large arolia, which are typically held upright; hence, their common name is heelwalkers. The first mantophasmatodean species were described based on two museum specimens originally collected in Tanzania and Namibia. To date, these insects have been observed at surprising levels of diversity and abundance in Namibia and South Africa. For our studies on the phylogenetic relationships within Mantophasmatodea, we collected and analyzed numerous populations that belong to all known mantophasmatodean lineages, including East African populations. These collections not only provided a comprehensive biogeographical overview but also facilitated a comparative analysis of behavior, which was mainly analyzed under laboratory conditions. Here, we review and discuss the published data, as well as provide additional information on Mantophasmatodea distribution, evolutionary lineages, morphology, and biology, with a specific focus on reproductive biology.

Evolution and Diversity of Vibrational Signals in Mantophasmatodea (Insecta)

Vibrational communication for species identification and mate location is widespread among insects. We investigated the vibrational communication signals of 13 species of the insect order Mantophasmatodea (Heelwalkers). Males and females produce percussive signals by tapping their abdomens on the substrate to locate conspecific mates. We show that male and female calls are of similar general structure but differ in temporal characteristics. Using a principal component analysis, we demonstrate that most species can be distinguished by their calls only. Mapping the calls onto an existing molecular phylogenetic tree reveals a slow diverging drift of male call pattern but no specific trend. For females, a trend from faster towards slower pulse repetition times is indicated. Two sympatric species, Karoophasma biedouwense and Viridiphasma clanwilliamense (Austrophasmatidae), exhibit very different call parameters. The latter species produces calls rather different from all other investigated species, which might hint at reproductive character displacement.

Peptidomics-Based Phylogeny and Biogeography of Mantophasmatodea (Hexapoda)

The insect order Mantophasmatodea was described in 2002. Prior to that time, several generations of entomologists had assumed that all major insect taxa were known; thus, its description was a sensation for zoologists. Since then, a surprising abundance and species diversity of this taxon have been found, particularly in the winter rainfall region of South Africa. To learn more about the evolutionary lineages, speciation, and biogeography of Mantophasmatodea, we applied an unusual peptidomics approach. We collected specimens of almost all known and novel taxa of these insects, developed methods for immediate sample preparation in the field, introduced peptide mass fingerprints for the unambiguous identification of taxa, and subsequently analyzed the most extensive data set on peptide hormones ever compiled for insect taxa. To account for intraspecific variation, we analyzed several individuals per putative species. Increased taxon sampling was preferred over a further increase in the number of characters to optimize the accuracy of phylogenetic analyses. The large data set made it possible to test the validity of using neuropeptide sequences, which coevolve with their respective receptors, to analyze phylogenetic relationships among closely related taxa. Altogether, the data from 71 populations of Mantophasmatodea were sufficient to clearly separate the major clades of Mantophasmatodea, including previously undescribed taxa such as Pachyphasma, Striatophasma, and Austrophasmatidae gen. et sp. nov. "RV." The data confirm the monophyly of Austrophasmatidae and show a relatively recent and extensive radiation in the winter rainfall region of South Africa but also suggest that the species-level diversification of Namibian Mantophasma is less marked than previously thought. We discuss the biogeographical and ecological factors that may have resulted in different regional patterns of endemism and species diversity in Mantophasmatodea. The unique development of the neuroendocrine capa-neurons in the ventral nervous system is described as synapomorphy of Mantophasmatodea + Grylloblattodea and is a further argument for a close relationship between these insect taxa.

Structure and sensory physiology of the leg scolopidial organs in Mantophasmatodea and their role in vibrational communication

Individuals of the insect order Mantophasmatodea use species-specific substrate vibration signals for mate recognition and location. In insects, substrate vibration is detected by mechanoreceptors in the legs, the scolopidial organs. In this study we give a first detailed overview of the structure, sensory sensitivity, and function of the leg scolopidial organs in two species of Mantophasmatodea and discuss their significance for vibrational communication. The structure and number of the organs are documented using light microscopy, SEM, and x-ray microtomography. Five scolopidial organs were found in each leg of male and female Mantophasmatodea: a femoral chordotonal organ, subgenual organ, tibial distal organ, tibio-tarsal scolopidial organ, and tarso-pretarsal scolopidial organ. The femoral chordotonal organ, consisting of two separate scoloparia, corresponds anatomically to the organ of a stonefly ( Nemoura variegata) while the subgenual organ complex resembles the very sensitive organs of the cockroach Periplatena americana (Blattodea). Extracellular recordings from the leg nerve revealed that the leg scolopidial organs of Mantophasmatodea are very sensitive vibration receptors, especially for low-frequency vibrations. The dominant frequencies of the vibratory communication signals of Mantophasmatodea, acquired from an individual drumming on eight different substrates, fall in the frequency range where the scolopidial organs are most sensitive.

Structure and function of the arolium of Mantophasmatodea (Insecta)

All species of the insect order Mantophasmatodea characteristically keep the 5th tarsomere and pretarsus (arolium plus two claws) turned upwards and off the substrate. The unusually large arolium was studied in two species of Mantophasmatodea using bright field light microscopy, reflection microscopy, fluorescence microscopy, TEM, SEM, and Cryo-SEM. It contains an epithelial gland, numerous tracheoles, and nerves. The gland consists of enlarged epithelial cells with large nuclei, mitochondria, RER, golgi complexes, microtubules, and numerous secretion vesicles. Evidence for exocytosis of the vesicles into the gland reservoir between the epithelial gland and the thick cuticle could be observed. Cryo-SEM revealed that the ventral side of the arolium and distal part of its dorsal side are covered with a liquid film. Fluid footprints of arolia of individuals walking on a glass plate also indicate the presence of secretory fluid on the arolium surface. Behavioral experiments using animals with ablated arolia showed that representatives of Mantophasmatodea do not need their arolia to detect and respond to vibratory communication signals nor to catch small to medium-sized prey. Individuals with ablated arolia were not able to move upside down on a smooth glass plate. We conclude that Mantophasmatodea use their arolia for attachment when additional adhesion force is required (e.g. windy conditions, handling large prey, mating). They can bring their arolia in contact with the surface in a very fast reflex (18.0 +/- 9.9 ms). The secretory fluid found on the surface is produced by the gland and transported to the outside, presumably through small pore channels, to enhance adhesion to the substrate.

Postembryonic development of the unique antenna of Mantophasmatodea (Insecta)

The postembryonic antennal development and life cycle of a member of the insect order Mantophasmatodea ( Lobatophasma redelinghuysense) was investigated using a series of annulus counts and a time sequence of head capsule measurements. The life cycle comprised six instars. Females achieved significantly larger head capsules from instar 2 onwards, resulting in adult females having a larger mean head capsule diameter (2.58 mm) than males (2.27 mm). Antennae of first instar larvae comprised a smooth four-segmented basiflagellum and a seven-segmented, sensilla-rich distiflagellum. Lengthening of the basiflagellum was achieved by the addition of two annuli per moult, generated by division of the basal annulus (meriston). Annulus number and the unique annulation pattern of the distiflagellum remained constant until adulthood. The segmentation pattern of adult antennae (comprising a basiflagellum and a distiflagellum of 14 and seven annuli respectively) and mode of antennal elongation was consistent for all 11 species examined. Subdivisions in basiflagellar annuli were observed in adults of all species examined, although they are not considered to be true annular divisions. The structure of the mantophasmatodean antenna appears to be autapomorphic within Insecta, bearing little resemblance to that of Grylloblattodea, Dictyoptera or Phasmatodea, all putative sister groups of the Mantophasmatodea. However, the mode of flagellar elongation most closely resembles that of Isoptera, Blattaria and Dermaptera.

Vibrational Communication in Two Sympatric Species of Mantophasmatodea (Heelwalkers)

The communication via percussion of the abdomen on the substrate for species recognition and mate location of males and females of two sympatric species of the recently described insect order Mantophasmatodea (Heelwalkers) was investigated. Each sex produced a single and distinctive call. The female call consisted of repeated single pulses, whereas the more complex male call comprised repeated pulse trains. The calls of males and females of the two species were of similar general structure, but differed in most temporal characters such as pulse and pulse train repetition time. In behavioral playback experiments females reacted to the call of conspecific males by calling and decreasing locomotion. When stimulated with the call of the heterospecific, sympatric male, females showed no reaction. Males exhibited abdominal rubbing, high tapping rates, increased activity (both movement and active searching) as well as characteristic searching behavior at branch nodes, when presented with the conspecific female call. Being stimulated with the playback of the heterospecific female call and the conspecific male call respectively, males responded with less intense locomotor and searching behavior. The drumming behavior in the control situation (no playback) suggests that males sometimes call in the absence of other individuals.

Corazonin in insects

Corazonin is a peptidergic neurohormone of insects that is expressed in neurosecretory neurons of the pars lateralis of the protocerebrum and transported via nervi corporis cardiaci to the storage lobes of the corpora cardiaca. This peptide occurs with a single isoform in all insects studied so far, with the exception of the Coleoptera in which no corazonin form could be detected. Very few modifications of [Arg 7]-corazonin, originally isolated from cockroaches, are known, namely [His 7]-corazonin which is expressed in certain locusts and the stick insect Carausius morosus, and [Thr 4, His 7]-corazonin recently described from the honey bee Apis mellifera. In this study, we performed a comprehensive screening for corazonin in the different insect groups after detecting of a fourth isoform in a crane fly, Tipula sp. ([Gln 10]-corazonin). [Arg 7]-corazonin is distributed in most major lineages of insects, and is thus the ancient form which was present at the time the phylum Insecta evolved. The replacement of Arg with His at position 7 from the N-terminus occurred several times in the evolution of insects. The third isoform, [Thr 4, His 7]-corazonin, seems to be restricted to bees (Apidae); whereas wasps (Vespidae) and a bumble bee (Apidae) express other corazonins, specifically [His 7]-corazonin and [Tyr 3, Gln 7, Gln 10]-corazonin, respectively. A novel corazonin form, [His 4, Gln 7]-corazonin, was also detected in all South African members of the newly described insect order Mantophasmatodea. The [His 4, Gln 7]-corazonin separates these species from the Namibian Mantophasmatodea which express [Arg 7]-corazonin and can be used as a distinct character to distinguish these morphologically similar insects.

The newly discovered insect order Mantophasmatodea contains a novel member of the adipokinetic hormone family of peptides

A novel member of the AKH/RPCH family of peptides has been identified from the corpus cardiacum of an, as yet, unidentified species of the newly discovered insect order Mantophasmatodea from Namibia. The primary sequence of the peptide, which is denoted Manto-CC, was deduced from multiple MS N electrospray mass data to be an octapeptide: pGlu-Val-Asn-Phe-Ser-Pro-Gly-Trp amide. Synthetic Manto-CC co-elutes on reversed-phase HPLC with the natural peptide from the gland of the insect. Interestingly, Manto-CC is structurally very closely related (only one point mutation) to the AKH/RPCH peptides previously identified in mostly more basal insect taxa (Odonata, Blattodea, and Ensifera) and in Crustacea, the sister group of insects, whereas larger structural differences occur with peptides from Mantodea and Phasmatodea, which are thought to be close relatives of Mantophasmatodea. Functionally, Manto-CC may be employed to activate glycogen phosphorylase to mobilize carbohydrates.

New insect order Mantophasmatodea: species differentiation by mass fingerprints of peptide hormones?

We analysed peptide hormones of South African species of the recently described insect order Mantophasmatodea. Mass spectrometric techniques made it possible to analyse minute amounts of material stored in different neurohemal organs of single specimens. The methodological approach underlying this application is described and resulted in the first completely sequenced peptide hormones of the Mantophasmatodea, namely adipokinetic hormone, leucomyosuppressin, and a novel member of the periviscerokinins. The extensive peptide screening revealed a surprisingly clear differentation of species by peptide mass fingerprints. This is the first successful attempt to catalogue neuropeptides of insects for systematic/taxonomic purposes. In total, 14 of 32 peptides differed across species. Moreover, the data presented here show a hierarchy in the tendency for modifications among the different peptide hormones. Die vorliegende Arbeit beschreibt eine umfassende Analyse von Peptidhormonen der kürzlich beschriebenen Insektenordnung Mantophasmatodea. Mittels moderner massenspektrometrischer Methoden ist es gelungen, die Neurohaemalorgane von einzelnen Individuen verschiedener Arten zu untersuchen. Der methodische Ansatz hierzu wird vorgestellt und die ersten komplett sequenzierten Neurohormone der Mantophasmatodea beschrieben. Die Ergebnisse belegen eine überrraschend klare Differenzierbarkeit der Arten anhand der ermittelten Massendaten, und ermöglichen es erstmals, Neuropeptide für taxonomisch/systematische Zielstellungen zu katalogisieren. Die vorliegenden Daten bestätigen zudem eine unterschiedliche Tendenz zu Sequenzmodifizierungen zwischen den verschiedenen Peptidfamilien.

A New Rock Crawler in Baltic Amber, with Comments on the Order(Mantophasmatodea: Mantophasmatidae)

A new fossil species of the recently described insect order Mantophasmatodea (Polyneoptera: Anartioptera), the “African rock crawlers”, is described and figured from Eocene (Lutetian) Baltic amber. Adicophasma spinosa, new genus and species, differs from the only other fossil of this lineage, Raptophasma, by the strong spination of the fore- and midlegs, broad abdominal segments, and absence of dorsal carinae on the profemur, resembling in these respects the living African genera Mantophasma and Praedatophasma. The position of the fossil and of the order among polyneopterous insects is briefly discussed.

A Review of the Order Mantophasmatodea (Insecta)

The newly discovered insect order Mantophasmatodea, known from two Recent species in tropical Africa and some fossils in Baltic amber, is reviewed, with all the material currently known being listed. A new genus and species is described: Praedatophasma maraisi Zompro & Adis, n. gen., n. sp. Complete information available at present on habitats and the biology is given.