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Captive breeding can be a useful tool for the management of threatened species, but such programs often begin with a bottleneck which may lower reproductive fitness by increasing inbreeding and allowing deleterious alleles to increase in frequency by reducing effective population size. Dryococelus australis, the Lord Howe Island stick insect, is a critically endangered insect that has been bred at the Melbourne Zoo in Melbourne, Australia, since shortly after the species was rediscovered in 2001. We analysed a long‐term dataset of phenotypic measurements from this captive breeding program to determine whether reproductive fitness has declined in captivity. We found a clear signal of decline in direct (egg hatching success) and indirect (egg and nymph size) fitness indicators over time. We compared a captive line descended from the original program founders to a new hybrid line that has recent wild ancestry. The hybrid line showed an immediate improvement in egg hatch rate, suggesting the potential for genetic rescue. Egg and nymph size did not show as dramatic a change, although this line had only existed for just over a single generation at the time of data collection. These results argue strongly for the regular sourcing of new genetic material from the wild D. australis population to counteract fitness declines in captivity. Aside from benefiting the captive population, this would also improve the prospects of establishing new wild populations in the future, using individuals sourced from captivity. [ABSTRACT FROM AUTHOR]

Chemical defence in insects is an increasingly popular subject of research and has the potential for providing unexplored compounds with unknown properties for drug and repellent discovery, so the secretions of various species of insects are currently being studied, and new ways of collecting these secretions are being sought. Silica gel and activated carbon were used as absorbents to collect the sprayed defensive secretion of Eurycantha calcarata. Using gas chromatography coupled with mass spectrometry, 49 compounds were identified, including 19 carboxylic acids, nine esters, ten alcohols, five hydrocarbons, and other organic compounds. The most abundant two compounds from each group were: hexadecanoic acid, octadecanoic acid, 9-hexadecenoic acid octadecyl ester, hexadecanoic acid tetradecyl ester, octacosanol, triacontanol, tridecane, and tetradecane. Silica gel turned out to be a better absorbent because it captured more compounds than the activated carbon. The mass of the absorbent did not affect the quality of the analyses. This paper is the first describing the volatile secretions emitted by phasmid representatives that originate from abdominal structures rather than the glands on prothorax. The presented results of the analyses and the known properties of the detected compounds give grounds for the conclusion that these secretions are of importance for defence in this species of phasmid. [ABSTRACT FROM AUTHOR]

Colours in nature can be pigmentary, structural or a combination of both. The prevalence, function and nanostructural origin of structural coloration in eggs is largely unknown. Stick and leaf insect eggs display a wide variety of colours, most of which are produced by pigments. The eggs of Myronides glaucus (Phasmida: Lonchodidae; Hennemann, 2021), however, show a clear purple to green iridescence. Here, we use micro‐spectrophotometry, Fourier‐transform infrared reflectance, transmission‐ and scanning electron microscopy, atomic force microscopy, finite‐difference time‐domain optical simulations and experimental approaches to elucidate the mechanism for iridescence in M. glaucus eggshells, which together reveal that iridescence is caused by thin‐film interference by a 200‐ to 450‐nm‐thick outermost layer. These results highlight the diversity of phasmid eggs and the need to study the different mechanisms and functions of structural coloration. [ABSTRACT FROM AUTHOR]

Facultative parthenogenesis is a form of reproduction in which females can either lay unfertilised eggs that typically develop into female offspring only or mate and lay fertilised eggs that develop into male and female offspring. Intriguingly, facultative parthenogens often occur in mixed‐sex populations where reproduction is mostly sexual and all‐female populations where reproduction is asexual. How all‐female populations avoid invasion by males remains unknown. Here, we explored the use of pheromones in male–female communication in a facultatively parthenogenetic stick insect, the peppermint stick insect (Megacrania batesii), and compared chemical signals between females descended from sexually versus parthenogenetically reproducing populations. If parthenogenetic females release less attractive pheromones, this could help explain the persistence of all‐female populations. We found that M. batesii exhibits slight sexual dimorphism in antenna morphology, and behavioural assays provided little evidence that males could locate females solely by volatile pheromones. However, CHC profiles differed substantially between different types of females. Analysis of CHC components indicated a clear genetic difference between females descended from all‐female versus mixed‐sex populations, as well as a maternal effect of female parthenogenetic versus sexual development. Together, our results suggest that males might rely more on close‐range chemical cues to differentiate females, and chemical communication could play a role in the persistence of all‐female populations. [ABSTRACT FROM AUTHOR]

Mechanoreceptor organs in hemimetabolous insects are physiologically important not only in the adult insects, but also for sensory functions in the juvenile postembryonic stages. They provide proprioceptive and exteroceptive information, e.g., in locomotion or orientation. In stick insects (Phasmatodea), the subgenual organ complex in the tibia of all legs is an elaborate mechanoreceptor system. This complex contains two chordotonal organs, the subgenual organ and the distal organ. These organs have mainly been studied in adult insects for the neuroanatomy and functional morphology. Here, the sensory organs were investigated in newly hatched Ramulus artemis (Westwood, 1859) to indicate the functional organisation at the beginning of postembryogenesis, when the detection of mechanical stimuli becomes relevant for behaviour. The organs were investigated by axonal tracing for the organ neuroanatomy, innervation, and number of sensilla in the distal organ. In addition, the sensory complex was analysed for the connection by a membrane between the organs. The organs are present after hatching, indicating in particular a possible vibration detection by the subgenual organ. In most cases, the connection between the sensory organs was also present. This indicates the development of sensory neurons and additional tissues during embryogenesis. The sensory neurons in the subgenual organ show a re-organisation, as the dorsal sensilla change from orientation in distal directions to proximal directions. This finding is discussed for implications in vibration detection. The overall results indicate some neuroanatomical modifications during postembryonic development, while the main structures of the subgenual organ complex already originate during embryonic development. [ABSTRACT FROM AUTHOR]

Stick insects (Phasmatodea) in general are remarkable for presenting striking camouflage-related adaptations. Even so, a considerable number of species are colorful and present other defense mechanisms, such as the New World lineage Pseudophasmatidae. Within this family, Urucumania currently comprises two described species occurring in Brazil, Bolivia and Paraguay, both of which have small scale-like wings. Urucumania is currently placed in Anisomorphini. However, two similar species under Pseudophasma present remarkable similarities with Urucumania species. These two species, Pseudophasma nigrovittatum and Pseudophasma dentata, are the only Pseudophasma presenting scale-like wings. Both inhabit Brazil, are known from a single sex and present a generally similar coloration pattern contrasting to that of Urucumania. Aiming to resolve whether these and other similar specimens represent distinct species, and if they belong to Urucumania rather than to Pseudophasma, we conducted a careful analysis of the external morphology of both sexes, eggs and the male genitalia. We transfer both scale-like winged Pseudophasma to Urucumania, redescribing them based on both sexes showing that the two described species are in fact distinct, and furthermore present 13 new species of Urucumania from Brazil and Bolivia: Urucumania pirulaisp. n., U. varellaisp. n., U. guadanucciisp. n., U. atilaisp. n., U. intervalicasp. n., U. brasilsp. n., U. tapirapesp. n., U. rasocatarinensissp. n., U. dilatatasp. n., U. sertanejasp. n., U. albopunctatasp. n., U. oriomadeirensissp. n. and U. candangasp. n. [ABSTRACT FROM AUTHOR]

Closely related sexual and parthenogenetic species often show distinct distribution patterns, known as geographical parthenogenesis. Similar patterns, characterized by the existence of separate sexual and parthenogenetic populations across their natural range, can also be found in facultative parthenogens – species in which every female is capable of both sexual and parthenogenetic reproduction. The underlying mechanisms driving this phenomenon in nature remain unclear. Features of the habitat, such as differences in host‐plant phenotypes or niche breadth, could favour sexual or asexual reproductive modes and thus help to explain geographical parthenogenesis in natural insect populations. Megacrania batesii is a facultatively parthenogenetic stick insect that displays geographical parthenogenesis in the wild. We aimed to explore whether sexual and parthenogenetic populations of M. batesii displayed niche differentiation or variations in niche breadth that could explain the separation of the two population types. To do this, we sampled host plants from across the range of M. batesii and quantified phenotypic traits that might affect palatability or accessibility for M. batesii, including leaf thickness, toughness, spike size and density, plant height, and chemical composition. We also quantified host‐plant density, which could affect M. batesii dispersal. We found little evidence of phenotypic differences between host plants supporting sexual versus asexual M. batesii populations, and no difference in host‐plant density or niche breadth between the two population types. Our results suggest that habitat parameters do not play a substantial role in shaping patterns of geographical parthenogenesis in wild populations of M. batesii. Instead, population sex ratio variation could result from interactions between the sexes or dispersal dynamics. [ABSTRACT FROM AUTHOR]

Scientific progress within the last few decades has revealed the functional morphology of an insect's sticky footpads—a compliant pad that secretes thin liquid films. However, the physico‐chemical mechanisms underlying their adhesion remain elusive. Here, we explore these underlying mechanisms by simultaneously measuring adhesive force and contact geometry of the adhesive footpads of live, tethered Indian stick insects, Carausius morosus, spanning more than two orders of magnitude in body mass. We find that the adhesive force we measure is similar to the previous measurements that use a centrifuge. Our measurements afford us the opportunity to directly probe the adhesive stress in vivo and use existing theory on capillary adhesion to predict the surface tension of the secreted liquid and compare it to previous assumptions. From our predictions, we find that the surface tension required to generate the adhesive stresses we observed ranges between 0.68 and 12 mN m−1${\rm m}^{-1}$. The low surface tension of the liquid would enhance the wetting of the stick insect's footpads and promote their ability to conform to various substrates. Our insights may inform the biomimetic design of capillary‐based, reversible adhesives and motivate future studies on the physico‐chemical properties of the secreted liquid. [ABSTRACT FROM AUTHOR]

Deploying static wireless sensor nodes is prone to network coverage gaps, resulting in poor network coverage. In this paper, an attempt is made to improve the network coverage by moving the locations of the nodes. A surrogate-assisted sine Phasmatodea population evolution algorithm (SASPPE) is used to evaluate the network coverage. A 50 × 50 hill simulation environment was tested for the number of nodes of 30 and 40 and radii of 3, 5 and 7, respectively. The results show that the SASPPE algorithm has the highest coverage, which can be up to 23.624% higher than the PPE algorithm, and up to 5.196% higher than the PPE algorithm, ceteris paribus. The SASPPE algorithm mixes the GSAM with LSAMs, which balances the computational cost of the algorithm and the algorithm's ability to find optimal results. The use of hierarchical clustering enhances the stable type of the LSAMs. In addition, LSAMs are easy to fall into local optimality when they are modeled with local data, and the use of sine Phasmatodea population evolution algorithm (Sine-PPE) for searching in LSAMs alleviates the time for the algorithm to fall into local optimality. On 30D, 50D, and 100D, the proposed algorithm was tested by 7 test functions. The results show that the algorithm has significant advantages on most functions. [ABSTRACT FROM AUTHOR]

The genus Presbistus and the family Aschiphasmatidae are recorded from Thailand for the first time. A new species of Presbistus Kirby, 1896, Presbistus muka sp. nov., is described from the Mahidol University Campus in Kanchanaburi, West Thailand based on both sexes and eggs. The new species is diagnosed and differentiated from its congenerics by its distinct colouration and by the notably short wings. Illustrations of adults, specimens in situ, host plants, records on biology and a distribution map are provided. A second Presbistus species, Presbistus vitivorus Bresseel & Constant, 2022 is also recorded from West Thailand, its distribution and morphology are briefly discussed. [ABSTRACT FROM AUTHOR]

Stick insects (Phasmatodea) have many different oviposition strategies, reflecting a range of adaptive behaviours and morphologies to best place and secure eggs in their environments. Oviposition strategies in Aotearoa New Zealand phasmids are not well documented, but the literature so far suggests that they drop individual eggs to the ground from their position in the foliage. Here, we present evidence for an oviposition strategy unique among the Rō stick insects of Aotearoa New Zealand. Individual female Spinotectarchus acornutus were observed inserting their eggs in a range of substrates, in particular the bark of trees and in spaces within the textured surfaces of tree fern trunks. We also highlight how the specific morphology of their eggs may be an adaptation to assist in substrate attachment, while their elongated secondary ovipositor could aid in egg insertion into substrates. [ABSTRACT FROM AUTHOR]

The article offers information on the Amateur Entomologists Society (AES) Young Entomologists' Day 2024 at the Natural History Museum in London, England. Topics discussed include the presentations by young entomologists; collaborations with youth nature groups and conservation trusts; and discussions on insect diversity, behavior and their cultural impact in computer games, design and fashion.

Simple Summary: Stick insects and their mechanoreceptors are important models for neurobiology and physiology. Mechanoreceptors are sensory systems that detect mechanical stimuli like wind, airborne sound, substrate vibration, or gravity. They are present in insects in highly diverse forms. Here, the morphology of a mechanosensory complex (the subgenual organ complex) with two distinct organs in the legs of a stick insect (Sipyloidea chlorotica) is described for animals that were newly hatched. The overall organisation of this sensory complex is unique in stick insects, and the present study extends the current knowledge from adult insects to the early juvenile instars. The morphological results show a connection between the two sensory organs (subgenual organ and distal organ) by a thin membrane, which had already been documented in adult stick insects. By the time of hatching, both the sensory neurons activated by mechanical stimuli as well as further tissues in the sensory complex are present, and they likely develop during embryogenesis. The sensory organs could also be functional at hatching. This report discusses the implications of a connection between the subgenual organ and the distal organ, suggesting that the membrane would influence the displacements of the two organs. The subgenual organ complex of stick insects has a unique neuroanatomical organisation with two elaborate chordotonal organs, the subgenual organ and the distal organ. These organs are present in all leg pairs and are already developed in newly hatched stick insects. The present study analyses for the first time the morphology of sensory organs in the subgenual organ complex for a membrane connecting the two sensory organs in newly hatched insects (Sipyloidea chlorotica (Audinet-Serville 1838)). The stick insect legs were analysed following hatching by axonal tracing and light microscopy. The subgenual organ complex in first juvenile instars shows the sensory organs and a thin membrane connecting the sensory organs resembling the morphology of adult animals. Rarely was this membrane not detected, where it is assumed as not developed during embryogenesis. The connection appears to influence the shape of the subgenual organ, with one end extending towards the distal organ as under tension. These findings are discussed for the following functional implications: (1) the physiological responses of the subgenual organ complex to mechanical stimuli after hatching, (2) the influence of the membrane on the displacement of the sensory organs, and (3) the connection between the subgenual organ and distal organ as a possible functional coupling. [ABSTRACT FROM AUTHOR]

Phenotypic variation within species can affect the ecological dynamics of populations and communities. Characterizing the genetic variation underlying such effects can help parse the roles of genetic evolution and plasticity in "eco-evolutionary dynamics" and inform how genetic variation may shape patterns of evolution. Here, we employ genome-wide association (GWA) methods in Timema cristinae stick insects and their co-occurring arthropod communities to identify genetic variation associated with community-level traits. Previous studies have shown that maladaptation (i.e. imperfect crypsis) of T. cristinae can reduce the abundance and species richness of other arthropods due to an increase in bird predation. Whether genetic variation that is independent of crypsis has similar effects is unknown and was tested here using genome-wide genotyping-by-sequencing data of stick insects, arthropod community information, and GWA mapping with Bayesian sparse linear mixed models. We find associations between genetic variation in stick insects and arthropod community traits. However, these associations disappear when host-plant traits are accounted for. We thus use path analysis to disentangle interrelationships among stick-insect genetic variation, host-plant traits, and community traits. This revealed that host-plant size has large effects on arthropod communities, while genetic variation in stick insects has a smaller, but still significant effect. Our findings demonstrate that (1) genetic variation in a species can be associated with community-level traits but that (2) interrelationships among multiple factors may need to be analyzed to disentangle whether such associations represent causal relationships. This work helps to build a framework for genomic studies of eco-evolutionary dynamics. [ABSTRACT FROM AUTHOR]

Reproduction is a key feature of all organisms, yet the way in which it is achieved varies greatly across the tree of life. One striking example of this variation is the stick insect genus Bacillus , in which five different reproductive modes have been described: sex, facultative and obligate parthenogenesis, and two highly unusual reproductive modes: hybridogenesis and androgenesis. Under hybridogenesis, the entire genome from the paternal species is eliminated and replaced each generation by mating with the corresponding species. Under androgenesis, an egg is fertilized, but the developing diploid offspring bear two paternal genomes and no maternal genome, as a consequence of unknown mechanisms. Here, we reevaluate the previous descriptions of Bacillus lineages and the proposed F1 hybrid ancestries of the hybridogenetic and obligately parthenogenetic lineages (based on allozymes and karyotypes) from Sicily, where all these reproductive modes are found. We generate a chromosome-level genome assembly for a facultative parthenogenetic species (B. rossius) and combine extensive field sampling with RADseq and mtDNA data. We identify and genetically corroborate all previously described species and confirm the ancestry of hybrid lineages. All hybrid lineages have fully retained their F1 hybrid constitution throughout the genome, indicating that the elimination of the paternal genome in hybridogens is always complete and that obligate parthenogenesis in Bacillus hybrid species is not associated with an erosion of heterozygosity as known in other hybrid asexuals. Our results provide a stepping stone toward understanding the transitions between reproductive modes and the proximate mechanisms of genome elimination. [ABSTRACT FROM AUTHOR]

The extent to which evolution is repeatable remains debated. Here, we study changes over time in the frequency of cryptic color-pattern morphs in 10 replicate long-term field studies of a stick insect, each spanning at least a decade (across 30 years of total data). We find predictable "up-and-down" fluctuations in stripe frequency in all populations, representing repeatable evolutionary dynamics based on standing genetic variation. A field experiment demonstrates that these fluctuations involve negative frequency-dependent natural selection (NFDS). These fluctuations rely on demographic and selective variability that pushes populations away from equilibrium, such that they can reliably move back toward it via NFDS. Last, we show that the origin of new cryptic forms is associated with multiple structural genomic variants such that which mutations arise affects evolution at larger temporal scales. Thus, evolution from existing variation is predictable and repeatable, but mutation adds complexity even for traits evolving deterministically under natural selection. [ABSTRACT FROM AUTHOR]

Phasmatodea, commonly known as stick insects, are recognized as noteworthy pests globally, impacting agriculture and forest ecosystems. Among them, the outbreak of Ramulus mikado has emerged as a notable concern in East Asian forests. Recently, Metarhizium phasmatodeae has been identified as utilizing stick insects as hosts. We have observed evidence of this entomopathogenic fungus infecting stick insects. Given the increase in these occurrences during the rainy period, this study investigated the relationship between the survival of R. mikado and the M. phasmatodeae infection during the rainy seasons of 2022 and 2023. We collected stick insects in two representative forests of the Republic of Korea and examined insect survival, fungal infection, and various environmental factors. No infections were detected in specimens collected in June before the rainy season, but from July onwards, both the mortality of R. mikado and the fungal infection substantially increased. By the last sampling date of each year, 75% (2022), 71.4% (2023) of the specimens were infected, and over 90% of the total individuals succumbed as a result. Fungi isolated from deceased R. mikado were successfully identified as M. phasmatodeae using morphological and taxonomic approaches. Various statistical analyses, including principal component analysis and modeling, revealed a robust association between fungal infection and the survival of stick insects. The results highlight the correlation between mass deaths of stick insects and fungal infection, particularly during the summer rainy season. These findings offer valuable insights for forecasting R. mikado population in the upcoming year and developing effective pest control strategies. [ABSTRACT FROM AUTHOR]

After the loss of a trait, theory predicts that the molecular machinery underlying its phenotypic expression should decay. Yet, empirical evidence is contrasting. Here, we test the hypotheses that (i) the molecular ground plan of a lost trait could persist due to pleiotropic effects on other traits and (ii) that gene co-expression network architecture could constrain individual gene expression. Our testing ground has been the Bacillus stick insect species complex, which contains close relatives that are either bisexual or parthenogenetic. After the identification of genes expressed in male reproductive tissues in a bisexual species, we investigated their gene co-expression network structure in two parthenogenetic species. We found that gene co-expression within the male gonads was partially preserved in parthenogens. Furthermore, parthenogens did not show relaxed selection on genes upregulated in male gonads in the bisexual species. As these genes were mostly expressed in female gonads, this preservation could be driven by pleiotropic interactions and an ongoing role in female reproduction. Connectivity within the network also played a key role, with highly connected—and more pleiotropic—genes within male gonad also having a gonad-biased expression in parthenogens. Our findings provide novel insight into the mechanisms which could underlie the production of rare males in parthenogenetic lineages; more generally, they provide an example of the cryptic persistence of a lost trait molecular architecture, driven by gene pleiotropy on other traits and within their co-expression network. [ABSTRACT FROM AUTHOR]

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Speciation is often viewed as a continuum along which populations diverge until they become reproductively-isolated species. However, such divergence may be heterogeneous, proceeding in fits and bursts, rather than being uniform and gradual. We show in Timema stick insects that one component of reproductive isolation evolves non-uniformly across this continuum, whereas another does not. Specifically, we use thousands of host-preference and mating trials to study habitat and sexual isolation among 42 pairs of taxa spanning a range of genomic differentiation and divergence time. We find that habitat isolation is uncoupled from genomic differentiation within species, but accumulates linearly with it between species. In contrast, sexual isolation accumulates linearly across the speciation continuum, and thus exhibits similar dynamics to morphological traits not implicated in reproductive isolation. The results show different evolutionary dynamics for different components of reproductive isolation and highlight a special relevance for species status in the process of speciation. Speciation may not be a mechanistically or temporally uniform process. We show divergent evolution of sexual versus habitat isolation and flat versus linear accumulation of the latter for within- versus between-species comparisons, revealing a critical role for species. [ABSTRACT FROM AUTHOR]

The article discusses the characteristics and behaviors of stick insects, also known as phasmids. These insects are known for their ability to camouflage themselves as vegetation, such as sticks, leaves, and twigs. They are inconspicuous and often hide in plain sight to avoid detection by predators. The article also mentions the limited research on phasmids and their genital morphology, as well as their popularity in popular culture and the pet trade. It highlights specific incidents involving stick insects, including their use in protests and their conservation efforts. [Extracted from the article]

Force feedback could be valuable in adapting walking to diverse terrains, but the effects of changes in substrate inclination on discharges of sensory receptors that encode forces have rarely been examined. In insects, force feedback is provided by campaniform sensilla, mechanoreceptors that monitor forces as cuticular strains. We neurographically recorded responses of stick insect tibial campaniform sensilla to "naturalistic" forces (joint torques) that occur at the hind leg femur-tibia (FT) joint in uphill, downhill, and level walking. The FT joint torques, obtained in a previous study that used inverse dynamics to analyze data from freely moving stick insects, are quite variable during level walking (including changes in sign) but are larger in magnitude and more consistent when traversing sloped surfaces. Similar to vertebrates, insects used predominantly extension torque in propulsion on uphill slopes and flexion torques to brake forward motion when going downhill. Sensory discharges to joint torques reflected the torque direction but, unexpectedly, often occurred as multiple bursts that encoded the rate of change of positive forces (dF/dt) even when force levels were high. All discharges also showed hysteresis (history dependence), as firing substantially decreased or ceased during transient force decrements. These findings have been tested in simulation in a mathematical model of the sensilla (Szczecinski NS, Dallmann CJ, Quinn RD, Zill SN. Bioinspir Biomim 16: 065001, 2021) that accurately reproduced the biological data. Our results suggest the hypothesis that sensory feedback from the femoro-tibial joint indicating force dynamics (dF/dt) can be used to counter the instability in traversing sloped surfaces in animals and, potentially, in walking machines. [ABSTRACT FROM AUTHOR]

Background: Phasmatodea are well known for their ability to disguise themselves by mimicking twigs, leaves, or bark, and are therefore commonly referred to as stick and leaf insects. In addition to this and other defensive strategies, many phasmatodean species use paired prothoracic repellent glands to release defensive chemicals when disturbed by predators or parasites. These glands are considered as an autapomorphic trait of the Phasmatodea. However, detailed knowledge of the gland anatomy and chemical compounds is scarce and only a few species were studied until now. We investigated the repellent glands for a global sampling of stick and leaf insects that represents all major phasmatodean lineages morphologically via µCT scans and analyzed the anatomical traits in a phylogenetic context. Results: All twelve investigated species possess prothoracic repellent glands that we classify into four distinct gland types. 1: lobe-like glands, 2: sac-like glands without ejaculatory duct, 3: sac-like glands with ejaculatory duct and 4: tube-like glands. Lobe-like glands are exclusively present in Timema, sac-like glands without ejaculatory duct are only found in Orthomeria, whereas the other two types are distributed across all other taxa (= Neophasmatodea). The relative size differences of these glands vary significantly between species, with some glands not exceeding in length the anterior quarter of the prothorax, and other glands extending to the end of the metathorax. Conclusions: We could not detect any strong correlation between aposematic or cryptic coloration of the examined phasmatodeans and gland type or size. We hypothesize that a comparatively small gland was present in the last common ancestor of Phasmatodea and Euphasmatodea, and that the gland volume increased independently in subordinate lineages of the Occidophasmata and Oriophasmata. Alternatively, the stem species of Neophasmatodea already developed large glands that were reduced in size several times independently. In any case, our results indicate a convergent evolution of the gland types, which was probably closely linked to properties of the chemical components and different predator selection pressures. Our study is the first showing the great anatomical variability of repellent glands in stick and leaf insects. [ABSTRACT FROM AUTHOR]

A review of published evidence indicates that Bactricia nematodes Kirby, 1894 is a nomen nudum because it is an unavailable name. The specimen collected during the Lund University Swedish South African Expedition and reported by this name is a male of Bactricia bituberculata (Schaum, 1857). [ABSTRACT FROM AUTHOR]

The article discusses a project called "Museums in Miniature" that aims to bring entomology education to South Carolina classrooms. The project involves creating mini-museums filled with preserved insect specimens and educational materials, which are then distributed to schools and libraries across the state. The mini-museums provide students with hands-on learning experiences and help foster an appreciation for insects and biodiversity. The project was funded by the Entomological Society of America's Chrysalis Fund and the South Carolina Entomological Society, and it has been successful in engaging students and promoting science education. [Extracted from the article]

Epigenetic mechanisms, such as DNA methylation, can influence gene regulation and affect phenotypic variation, raising the possibility that they contribute to ecological adaptation. Beginning to address this issue requires high‐resolution sequencing studies of natural populations to pinpoint epigenetic regions of potential ecological and evolutionary significance. However, such studies are still relatively uncommon, especially in insects, and are mainly restricted to a few model organisms. Here, we characterize patterns of DNA methylation for natural populations of Timema cristinae adapted to two host plant species (i.e. ecotypes). By integrating results from sequencing of whole transcriptomes, genomes and methylomes, we investigate whether environmental, host and genetic differences of these stick insects are associated with methylation levels of cytosine nucleotides in the CpG context. We report an overall genome‐wide methylation level for T. cristinae of ~14%, with methylation being enriched in gene bodies and impoverished in repetitive elements. Genome‐wide DNA methylation variation was strongly positively correlated with genetic distance (relatedness), but also exhibited significant host‐plant effects. Using methylome‐environment association analysis, we pinpointed specific genomic regions that are differentially methylated between ecotypes, with these regions being enriched for genes with functions in membrane processes. The observed association between methylation variation and genetic relatedness, and with the ecologically important variable of host plant, suggests a potential role for epigenetic modification in T. cristinae adaptation. To substantiate such adaptive significance, future studies could test whether methylation can be transmitted across generations and the extent to which it responds to experimental manipulation in field and laboratory studies. [ABSTRACT FROM AUTHOR]

Simple Summary: Members of the order Phasmida are popularly known as walking stick insects. They have remarkable camouflage, resembling moss, sticks, and leaves. Cladomorphus phyllinus is a giant stick insect from the Atlantic Forest of Brazil. Described in 1835 by George Robert Gray, the species is widely distributed in the wild, but several aspects of its biology and ecology remain to be studied. An inedited description of the first instar nymphs of C. phyllinus is presented, showing clear sexual dimorphism in the thorax and distinct abdominal sternites. A sex-specific suture was identified in the metanotum of males but was absent in females. Differentiation of the last three abdominal segments, which are already shaped to form the copulatory apparatus in both sexes, was also recorded and illustrated. Such sexual dimorphism is rare in first instar insect nymphs. Therefore, this study uncovered new characteristics that allow more precise data generation from samples collected in the field for conducting experiments, recording specimens in entomological collections, and improving the species concept and knowledge of sexual dimorphism in C. phyllinus. The first instar nymphs, both male and female, of the giant stick insect Cladomorphus phyllinus Gray, 1835 were carefully described and measured, revealing a remarkable sexual dimorphism that is considered rare among insects and is poorly explored in the order Phasmida. The studied F1 nymphs originated in captivity from eggs laid by a coupled female specimen collected in the Atlantic Forest in the vicinity of Petrópolis city, state of Rio de Janeiro, Brazil. The first instar nymphs of C. phyllinus were measured and illustrated in high-resolution photographs to show the general aspects and details of sexually dimorphic traits, making clear the phenotypic differences in the sexes. A total of 100 nymphs were kept alive until morphological sexual dimorphism was confirmed and quantified. All recently hatched first instar nymphs were separated based on the presumed male and female characteristics, i.e., the presence and absence of the suture in the metanotum in the males and females, respectively, had their sexes confirmed in 100% of the specimens as previously assigned. These results confirm this new morphological trait, which here is named "alar suture" as sex-specific in the first instar nymphs, a novelty in this stage of development of sexual differentiation. In addition, the distinct conformations of the last three abdominal sternites of both sexes were recorded. [ABSTRACT FROM AUTHOR]

Exploring how organisms overcome geographical barriers to dispersal is a fundamental question in biology. Passive long-distance dispersal events, although infrequent and unpredictable, have a considerable impact on species range expansions. Despite limited active dispersal capabilities, many stick insect species have vast geographical ranges, indicating that passive long-distance dispersal is vital for their distribution. A potential mode of passive dispersal in stick insects is via the egg stage within avian digestive tracts, as suggested by experimental evidence. However, detecting such events under natural conditions is challenging due to their rarity. Therefore, to indirectly assess the potential of historical avian-mediated dispersal, we examined the population genetic structure of the flightless stick insect Ramulus mikado across Japan, based on a multifaceted molecular approach [cytochrome oxidase subunit I (COI) haplotypes, nuclear simple sequence repeat markers and genome-wide single nucleotide polymorphisms]. Subsequently, we identified unique phylogeographic patterns, including the discovery of identical COI genotypes spanning considerable distances, which substantiates the notion of passive long-distance genotypic dispersal. Overall, all the molecular data revealed the low and mostly non-significant genetic differentiation among populations, with identical or very similar genotypes across distant populations. We propose that long-distance dispersal facilitated by birds is the plausible explanation for the unique phylogeographic pattern observed in this flightless stick insect. [ABSTRACT FROM AUTHOR]

Background: Phasmatodea (stick and leaf insects) play a central role on the debate regarding wing reduction and loss, and its wings are putative reacquisition from secondarily wingless ancestors based solely on extant species. A pivotal taxon in this respect is the species-poor Timematodea, consisting of approximately 21 wingless extant species, which form the sister group of all remaining winged or wingless stick and leaf insects, the Euphasmatodea. Results: Herein, the new fossils of Timematodea from mid-Cretaceous Kachin amber are reported, with winged and wingless species co-occurring. The palaeogeographic distributions of all fossils of Holophasmatodea are summarized, showing their wide paleo-distributions. The phylogenetic analysis based on morphological characters confirms the earliest-diverging lineage of winged Breviala cretacea gen. et sp. nov. in Timematodea, and the possible relationships among all families of Holophasmatodea. These are critical for the reconstruction of patterns of wing evolution in early Phasmatodea. Conclusions: The new fossils suggest that Timematodea once had wings, at least during the mid-Cretaceous. The palaeogeographic occurrences imply that Timematodea probably have been widely distributed since at least the Jurassic. The phylogenetic analysis with the ancestral-state reconstruction of wings indicates that the common ancestors of Holophasmatodea were winged, the reductions and losses of wings among Timematodea and Euphasmatodea have occurred independently since at least the Cretaceous, and the reduction or loss of the forewing earlier than the hind wings. [ABSTRACT FROM AUTHOR]

The first winged insects evolved from a wingless ancestor, but details of the transition to a fully-winged morphology remain unclear. Studying extant pterygotes with partial wings, such as the stick insects (order Phasmatodea), may help us to understand such a transition. Here, we address how a series of flight-related morphological parameters may correlate with flight evolution by studying different phasmids representing a volancy continuum ranging from miniaturized to full-sized wings. Variation in phasmid wing shape, venation, wing mass and the mass of flight muscle can be described by specific scaling laws referenced to wing length and wing loading. Also, the mass distribution of the body-leg system is conserved in spite of a wide range of variation in body shape. With reduced wing size and increased wing loading, the longitudinal position of the wing-bearing thoracic segments is shifted closer to the insects' centre of body mass. These results demonstrate complex reconfiguration of the flight system during wing morphological transitions in phasmids, with various anatomical features potentially correlated with reduced flight performance attained with partial wings. Although these data represent phasmid-specific features of the flight apparatus and body plan, the associated scaling relationships can provide insight into the functionality of intermediate conditions between wingless and fully-winged insects more generally. [ABSTRACT FROM AUTHOR]

Insects avoid predation in various ways, and some use multiple ways to avoid predation. However, the effects of comprehensive avoidance methods and the differences in avoidance methods among different life stages of insects have not been sufficiently discussed. The big head stick insect Megacrania tsudai uses background matching as its primary defense and chemical defense as its secondary defense. The aims of this study were to identify and isolate the chemical components of M. tsudai using repeatable methods, determine the amount of the main chemical compound, and reveal the effect of the main chemical compound on its predators. We established a repeatable gas chromatography-mass spectrometry (GC–MS) method to identify the chemical compounds of these secretions, and identified actinidine as the main compound. Actinidine was identified by nuclear magnetic resonance (NMR), and the amount of actinidine in each instar was calculated by constructing a calibration curve using pure actinidine. Mass ratios did not drastically change among instars. Furthermore, experiments involving dropping an aqueous solution of actinidine demonstrated removal behavior in geckos, frogs, and spiders. These results indicated that M. tsudai conducts secondary defenses using defensive secretions consisting mainly of actinidine. [ABSTRACT FROM AUTHOR]

The article explores rapid evolution induced by human activities, highlighting a study by Ni et al. that demonstrates how deforestation alters species interactions and leads to color changes in the Batesian mimic, Zelandoperla. Topics include the mechanisms of evolution through altered predation dynamics, the implications of predicting evolutionary responses to environmental changes, and the integration of ecological and genetic data to enhance understanding of evolutionary processes.

Obligately parthenogenetic species are expected to be short lived since the lack of sex and recombination should translate into a slower adaptation rate and increased accumulation of deleterious alleles. Some, however, are thought to have been reproducing without males for millions of years. It is not clear how these old parthenogens can escape the predicted long-term costs of parthenogenesis, but an obvious explanation is cryptic sex. In this study, we screen for signatures of cryptic sex in eight populations of four parthenogenetic species of Timema stick insects, some estimated to be older than 1 Myr. Low genotype diversity, homozygosity of individuals and high linkage disequilibrium (LD) unaffected by marker distances support exclusively parthenogenetic reproduction in six populations. However, in two populations (namely, of the species Timema douglasi and T. monikensis) we find strong evidence for cryptic sex, most likely mediated by rare males. These populations had comparatively high genotype diversities, lower LD, and a clear LD decay with genetic distance. Rare sex in species that are otherwise largely parthenogenetic could help explain the unusual success of parthenogenesis in the Timema genus and raises the question whether episodes of rare sex are in fact the simplest explanation for the persistence of many old parthenogens in nature. [ABSTRACT FROM AUTHOR]

Cyborg control of insect movement is promising for developing miniature, high-mobility, and efficient biohybrid robots. However, considering the inter-individual variation of the insect neuromuscular apparatus and its neural control is challenging. We propose a hierarchical model including inter-individual variation of muscle properties of three leg muscles involved in propulsion (retractor coxae), joint stiffness (pro- and retractor coxae), and stance-swing transition (protractor coxae and levator trochanteris) in the stick insect Carausius morosus. To estimate mechanical effects induced by external muscle stimulation, the model is based on the systematic evaluation of joint torques as functions of electrical stimulation parameters. A nearly linear relationship between the stimulus burst duration and generated torque was observed. This stimulus-torque characteristic holds for burst durations of up to 500ms, corresponding to the stance and swing phase durations of medium to fast walking stick insects. Hierarchical Bayesian modeling revealed that linearity of the stimulus-torque characteristic was invariant, with individually varying slopes. Individual prediction of joint torques provides significant benefits for precise cyborg control. [ABSTRACT FROM AUTHOR]

Attachment to the substrate is an important phenomenon that determines the survival of many organisms. Most insects utilize wet adhesion to support attachment, which is characterized by fluids that are secreted into the interface between the tarsus and the substrates. Previous research has investigated the composition and function of tarsal secretions of different insect groups, showing that the secretions are likely viscous emulsions that contribute to attachment by generating capillary and viscous adhesion, leveling surface roughness and providing self-cleaning of the adhesive systems. Details of the structural organization of these secretions are, however, largely unknown. Here, we analyzed footprints originating from the arolium and euplantulae of the stick insect Medauroidea extradentata using cryo-scanning electron microscopy (cryo-SEM) and white light interferometry (WLI). The secretion was investigated with cryo-SEM, revealing four morphologically distinguishable components. The 3D WLI measurements of the droplet shapes and volumes over time revealed distinctly different evaporation rates for different types of droplets. Our results indicate that the subfunctionalization of the tarsal secretion is facilitated by morphologically distinct components, which are likely a result of different proportions of components within the emulsion. Understanding these components and their functions may aid in gaining insights for developing adaptive and multifunctional biomimetic adhesive systems. [ABSTRACT FROM AUTHOR]

The walking-stick insect Ramulus mikado is occasionally considered a forest pest, as its mass occurrence can cause severe defoliation. It overwinters as eggs on the ground surface, and the hatched nymphs climb up to the host trees in spring. In this study, temperature-dependent development experiments were performed on R. mikado eggs under three constant temperatures (23.3, 28.3, and 29.2 °C) to extend the previously reported thermal response. The development times of eggs collected in summer and winter were also compared to investigate how development status is influenced by the seasons. The lower and upper developmental thresholds and thermal constants of R. mikado eggs were estimated to be 6.1 °C, 29.2 °C, and 1707.8 DD, respectively. The starting point for effective temperature effects on the eggs was estimated to be 1 August, based on the results of the experiment on field-collected eggs. A phenology model was constructed by using a development completion model scaled by the thermal constant, with a starting point of degree-day accumulation. The model showed good agreement, with a deviation of 3.2 ± 2.95 days between prediction and observation. The developed phenology model is useful for determining the appropriate timing for management decision-making regarding this insect. [ABSTRACT FROM AUTHOR]

Stick insects respond to visual or tactile stimuli with whole-body turning or directed reach-to-grasp movements. Such sensory-induced turning and reaching behaviour requires interneurons to convey information from sensory neuropils of the head ganglia to motor neuropils of the thoracic ganglia. To date, descending interneurons are largely unknown in stick insects. In particular, it is unclear whether the special role of the front legs in sensory-induced turning and reaching has a neuroanatomical correlate in terms of descending interneuron numbers. Here, we describe the population of descending interneurons with somata in the brain or gnathal ganglion in the stick insect Carausius morosus, providing a first map of soma cluster counts and locations. By comparison of interneuron populations with projections to the pro- and mesothoracic ganglia, we then estimate the fraction of descending interneurons that terminate in the prothoracic ganglion. With regard to short-latency, touch-mediated reach-to-grasp movements, we also locate likely sites of synaptic interactions between antennal proprioceptive afferents to the deutocerebrum and gnathal ganglion with descending or ascending interneuron fibres. To this end, we combine fluorescent dye stainings of thoracic connectives with stainings of antennal hair field sensilla. Backfills of neck connectives revealed up to 410 descending interneuron somata (brain: 205 in 19 clusters; gnathal ganglion: 205). In comparison, backfills of the prothorax-mesothorax connectives stained only up to 173 somata (brain: 83 in 16 clusters; gnathal ganglion: 90), suggesting that up to 60% of all descending interneurons may terminate in the prothoracic ganglion (estimated upper bound). Double stainings of connectives and antennal hair field sensilla revealed that ascending or descending fibres arborise in close proximity of afferent terminals in the deutocerebrum and in the middle part of the gnathal ganglia. We conclude that two cephalothoracic pathways may convey cues about antennal movement and pointing direction to thoracic motor centres via two synapses only. [ABSTRACT FROM AUTHOR]

Accurate taxonomical identification is an extremely important basis for stick insect research, including evolutionary biology but also applied biology such as pest control. In addition, genetic methods are a valuable identification auxiliary technology at present. Therefore, this paper used morphological and molecular data to investigate five stick insect specimens from the genus Cnipsomorpha in Yunnan, successfully identifying two new species: Cnipsomorpha yunnanensis Xu, Jiang & Yang, sp. nov. and C. yuxiensis Xu, Jiang & Yang, sp. nov. A phylogenetic tree was constructed through their 28S and COI genes in order to infer the phylogenetic position of the two new species. Photographs of the new species and a key to all known Cnipsomorpha species are provided. [ABSTRACT FROM AUTHOR]

Herbivorous insects require an active lignocellulolytic microbiome to process their diet. Stick insects (phasmids) are common in the tropics and display a cosmopolitan host plant feeding preference. The microbiomes of social insects are vertically transmitted to offspring, while for solitary species, such as phasmids, it has been assumed that microbiomes are acquired from their diet. This study reports the characterization of the gut microbiome for the Gray’s Malayan stick insect, Lonchodes brevipes, reared on native and introduced species of host plants and compared to the microbiome of the host plant and surrounding soil to gain insight into possible sources of recruitment. Clear differences in the gut microbiome occurred between insects fed on native and exotic plant diets, and the native diet displayed a more species-rich fungal microbiome. While the findings suggest that phasmids may be capable of adapting their gut microbiome to changing diets, it is uncertain whether this may lead to any change in dietary efficiency or organismal fitness. Further insight in this regard may assist conservation and management decision-making. [ABSTRACT FROM AUTHOR]

Ecological change drives rapid evolution, which then should feed back to influence ecological change. A new study uses experiments with Timema stick insects to demonstrate such feedbacks in nature, revealing that they can be very rapid, strong, and stabilizing. [ABSTRACT FROM AUTHOR]

The trade and keeping of exotic pets has serious implications for both biosecurity and biodiversity conservation. In Australia, the online trade of live invertebrates is an understudied and unregulated issue, with almost non‐existent monitoring. It is uncertain what species are being traded, whether they are being identified correctly, and how they are being sourced (i.e., captive bred or wild harvested, native, or alien). Consequently, potential invasion risks and conservation concerns remain unknown. Here, we explored the online trade of terrestrial invertebrates in Australia across a range of publicly available e‐commerce platforms. We detected 264 species of invertebrate traded, from 71 families and 168 genera over 12 months. The native Extatosoma tiaratum (giant prickly stick insect) was the most traded species, while the most popular families were Phasmatidae (stick insects), Formicidae (ants) and Theraphosidae (tarantulas). Three species are known to be invasive in Australia, while 87% of species traded were native. The conservation status of almost of the species (92%) listed in the invertebrate trade has not been evaluated. Exploring socio‐demographic relationships, we found that human population density was positively correlated with the location of invertebrate sellers. Further, we found the classifieds website had lower prices in contrast to traditional online pet‐stores (median of c. A$7 less). Finally, we did not observe a saturation in the number of species traded in our one‐year study, exemplifying the need for large scale monitoring and risk assessments for Australia's online terrestrial invertebrate trade. We recommend continued surveillance of live invertebrate trade on e‐commerce sites. Substantial changes to legislation and monitoring methods are required at a national level to control the vast number of invertebrates traded across the country, and to minimise the future risks of the invertebrate trade. [ABSTRACT FROM AUTHOR]

Living animals and legged robots share similar challenges for movement control. In particular, the investigation of neural control mechanisms for the self‐organized locomotion of insects and hexapod robots can be informative for other fields. The Annam stick insect Medauroidea extradentata is used as a template to develop a biorobotic model to infer walking self‐organization with strongly heterogeneous leg lengths. Body dimensions and data on the walking dynamics of the actual stick insect are used for the development of a neural control mechanism, generating self‐organized gait patterns that correspond to the real insect observations. The combination of both investigations not only proposes solutions for distributed neural locomotion control but also enables insights into the neural equipment of the biological template. Decentralized neural central pattern generation is utilized with phase modulation based on foot contact feedback to generate adaptive periodic base patterns and a radial basis function premotor network in each leg based on the target trajectories of actual stick insect legs during walking for complex intralimb coordination and self‐organized interlimb coordination control. Furthermore, based on both study objects, a robot with heterogeneous leg lengths is constructed to preliminary validate the findings from the simulations and real insect observations. [ABSTRACT FROM AUTHOR]