Distinct roles of the Hox genes Ultrabithorax and abdominal-A in scorpionfly embryonic proleg development.

The abdominal appendages of larval insects have a complex evolutionary history of gain and loss, but the regulatory mechanisms underlying the abdominal appendage development remain largely unclear. Here, we investigated the embryogenesis of abdominal prolegs in the scorpionfly Panorpa liui Hua (Mecoptera: Panorpidae) using in situ hybridization and parental RNA interference. The results show that RNAi-mediated knockdown of Ultrabithorax (Ubx) led to a homeotic transformation of the first abdominal segment (A1) into the third thoracic segment (T3) and changed the distributions of the downstream target Distal-less (Dll) expression but did not affect the expression levels of Dll. Knockdown of abdominal-A (abd-A) resulted in malformed segments, abnormal prolegs and disrupted Dll expression. The results demonstrate that the gene Ubx maintains an ancestral role of modulating A1 appendage fate without preventing Dll initiation, and a secondary adaptation of abd-A evolves the ability to specify abdominal segments and proleg identity. We conclude that changes in abdominal Hox gene expression and their target genes regulate abdominal appendage morphology during the evolutionary course of holometabolous larvae.

The Hox gene Abdominal-B regulates the appendage development during the embryogenesis of scorpionflies.

The Homeotic Complex (Hox) genes encode conserved homeodomain transcription factors that specify segment identity and appendage morphology along the antero-posterior axis in bilaterian animals. The Hox gene Abdominal-B (Abd-B) is mainly expressed in the posterior segments of the abdomen and plays an important role in insect organogenesis. In Mecoptera, the potential function of this gene remains unclear yet. Here, we performed a de novo transcriptome assembly and identified an Abd-B ortholog in the scorpionfly Panorpa liui. Quantitative real-time reverse transcription PCR showed that Abd-B expression increased gradually in embryos 76 h post oviposition, and was mainly present in the more posterior abdominal segments. Embryonic RNA interference of Abd-B resulted in a set of abnormalities, including developmental arrest, malformed suckers and misspecification of posterior segment identity. These results suggest that Abd-B is required for the proper development of the posterior abdomen. Furthermore, in Abd-B RNAi embryos, the expression of the appendage marker Distal-less (Dll) was up-regulated and was additionally present on abdominal segments IX and X compared with wild embryos, suggesting that scorpionfly Abd-B may act to suppress proleg development and has gained the ability to repress Dll expression on the more posterior abdominal segments. This study provides additional information on both the functional and evolutionary roles of Abd-B across different insects.

Molecular phylogeny of Panorpidae (Insecta: Mecoptera) based on mitochondrial and nuclear genes.

Panorpidae are the largest family in Mecoptera, covering approximately 70% species of the order. However, the phylogenetic relationship within Panorpidae has not been adequately explored. Here we analyzed the phylogenetic relationships among 70 species of five genera in Panorpidae using maximum likelihood and Bayesian inference based on two mitochondrial (cox1 and cox2) and one nuclear (28S rRNA) gene fragments with Panorpodes kuandianensis and Brachypanorpa carolinensis in Panorpodidae as outgroups. The results show that the genera Neopanorpa, Sinopanorpa and Dicerapanorpa are monophyletic, while the widespread genus Panorpa is reconfirmed to be a paraphyletic group. The P. centralis group is monophyletic and may merit a generic status, while the P. davidi and P. amurensis groups are paraphyletic. The divergence time estimated from BEAST analysis indicates that the Panorpidae may originate in the period from early Paleogene (63.6mya) to middle Eocene (41.2mya), and most diversification within Panorpidae occurred in the Cenozoic. The phylogeny and biogeography of Panorpidae are briefly discussed.

Four Forensic Entomology Case Studies: Records and Behavioral Observations on Seldom Reported Cadaver Fauna With Notes on Relevant Previous Occurrences and Ecology.

A yearlong survey of insect taxa associated with human decomposition was conducted at the Southeast Texas Applied Forensic Science (STAFS) facility located in the Center for Biological Field Studies of Sam Houston State University in Huntsville, TX. During this study, four insect-cadaver interactions were observed that represent previously poorly documented yet forensically significant interactions: Syrphidae maggots colonized a corpse in an aquatic situation; Psychodidae adults mated and oviposited on an algal film that was present on a corpse that had been recently removed from water; several Panorpidae were the first insects to feed upon a freshly placed corpse in the autumn; and a noctuid caterpillar was found chewing and ingesting dried human skin. Baseline knowledge of insect-cadaver interactions is the foundation of forensic entomology, and unique observations have the potential to expand our understanding of decomposition ecology.

Biodiversity and Spatiotemporal Variations of Mecoptera in Thailand: Influences of Elevation and Climatic Factors.

Ecological analyses of the small and lesser-known insect order Mecoptera in Thailand are presented. Specimens were collected monthly over a period of 12 consecutive months, using both Malaise and pan traps, from 29 sampling sites located in 18 national parks throughout Thailand. A total of 21 species in four genera were identified from 797 specimens, including Panorpa (1 species), Neopanorpa (18 species), Bittacus (1 species), and Terrobittacus (1 species), with the latter genus representing a new genus record to Thailand. Neopanorpa harmandi, N. siamensis, N. byersi, and N. malaisei were the most abundant species, representing 27.4%, 11.3%, 10.3% and 8.8% of the total specimens, respectively. The species with the highest frequency, as indicated by the high percentage of species occurrence (%SO), was N. siamensis (51%), followed by N. byersi (34%), N. harmandi (34%), N. spatulata (27%), and N. inchoata (27%). Eleven species (52%) exhibited specific regional occurrences. N. tuberosa and N. siamensis had the widest distribution, being found in almost all regions except for western and southern regions for the first and second species, respectively. The seasonal species richness of Mecoptera was high during the rainy season in the northern, northeastern, central, eastern, and western regions, with the highest richness observed in July (15 species), followed by the hot (10 species) and cold seasons (7 species), while there was no significant difference in species richness between seasons in the southern region. Multiple regression models revealed a negative association between species richness and abundance of Mecoptera with both elevation and temperature, and a positive association between rainfall and species evenness. It is predicted that climatic changes will have a detrimental effect on the mecopteran community. The results of this study enhance the understanding of the ecological aspects of Mecoptera, offering crucial insights into its biodiversity and distribution, which are vital for conservation and forest management.

The Distribution Pattern and Species Richness of Scorpionflies (Mecoptera: Panorpidae).

The uneven distribution of species diversity on earth, with mountainous regions housing half of the high species diversity areas, makes mountain ecosystems vital to biodiversity conservation. The Panorpidae are ecological indicators, ideal for studying the impact of climate change on potential insect distribution. This study examines the impact of environmental factors on the distribution of the Panorpidae and analyzes how their distribution has changed over three historical periods, the Last Interglacial (LIG), the Last Glacial Maximum (LGM), and Current. The MaxEnt model is used to predict the potential distribution area of Panorpidae based on global distribution data. The results show that precipitation and elevation are the primary factors affecting species richness, and the suitable areas for Panorpidae are distributed in southeastern North America, Europe, and southeastern Asia. Throughout the three historical periods, there was an initial increase followed by a decrease in the area of suitable habitats. During the LGM period, there was a maximum range of suitable habitats for cool-adapted insects, such as scorpionflies. Under the scenarios of global warming, the suitable habitats for Panorpidae would shrink, posing a challenge to the conservation of biodiversity. The study provides insights into the potential geographic range of Panorpidae and helps understand the impact of climate change on their distribution.

Ultrastructure of Ejaculatory Ducts of Cerapanorpa nanwutaina and Furcatopanorpa longihypovalva (Mecoptera: Panorpidae).

The ultrastructure of the ejaculatory duct was investigated in the scorpionflies Cerapanorpa nanwutaina (Chou 1981) and Furcatopanorpa longihypovalva (Hua & Cai, 2009) (Mecoptera: Panorpidae) using light and transmission electron microscopy. The ejaculatory ducts of both species comprise a median duct and an accessory sac. The median duct consists of a basal lamina, a mono-layered epithelium, a subcuticular cavity, and an inner cuticle. The accessory sac contains a single layer of epithelium and a basal lamina. A muscular layer is present in the accessory sac of C. nanwutaina and in the median duct of F. longihypovalva. The epithelia in the median duct and the accessory sac are well developed, their cells containing numerous cisterns of rough endoplasmic reticulum, mitochondria, and microvilli. The secretions of the median duct are first extruded into the subcuticular cavity and then into the lumen through an inner cuticle, while the secretions of the accessory sac are discharged directly into the lumen. The ejaculatory duct of F. longihypovalva is longer and has thicker epithelium with more cell organelles and secretions than that of C. nanwutaina.

A new species of the genus Cerapanorpa (Mecoptera, Panorpidae) from the eastern Bashan Mountains.

BACKGROUND: Cerapanorpa Gao, Ma & Hua, 2016, an endemic genus of Panorpidae in central China's mountain regions, currently comprises 21 described species. Recently, the short-horned scorpionfly C.brevicornis (Hua & Li, 2007) was confirmed to contain two valid species by phylogeographic and morphological data. Individuals from the highlands of the eastern Bashan Mountains were suggested as a good species, separated from the original short-horned C.brevicornis. NEW INFORMATION: Cerapanorpaalpina sp. nov. was described from the alpine zone of the eastern Bashan Mountains in central China. The new species differs from its congeners by the following combination of characters: male bearing an extra-short anal horn on posterior margin of tergum VI; paramere elongate, extending beyond the median tooth of gonostylus and curved laterally at basal half; female medigynium slightly constricted medially without dorsal basal plate. The species number of Cerapanorpa is raised to 22.

Two new species of Cerapanorpa (Mecoptera, Panorpidae) from the Qinling and Minshan mountains.

Two new species of Cerapanorpa Gao, Ma & Hua, 2016 are described from the Qinling and Minshan mountains, respectively. Cerapanorpa qinlingensis sp. nov. can be readily distinguished from its congeners by the elongate hypovalves and the extremely developed basal process of gonostylus in male genitalia. Cerapanorpa minshana sp. nov. is characterized by its bifurcated parameres and a cluster of long black bristles on the inner apex of the gonocoxite. The number of species of Cerapanorpa is raised to 21. An updated key to species of Cerapanorpa is presented.

Complete mitochondrial genomes of Bittacus strigosus and Panorpa debilis and genomic comparisons of Mecoptera.

Mitochondrial genomes play a significant role in reconstructing phylogenetic relationships and revealing molecular evolution of insects. However, only four mitochondrial genomes were reported in Mecoptera to date. Here, we obtained two new complete mitochondrial genomes of the hangingfly Bittacus strigosus Hagen, 1861 and the scorpionfly Panorpa debilis Westwood, 1846. The results show that the complete mitogenome sequences of B. strigosus and P. debilis are 15,825 and 17,018 bp, respectively, both containing 37 genes and one control region. The mecopteran mitogenomes are highly similar in A + T bias, AT-skew, and GC-skew. Tandem repeats of the control region were discovered in Mecoptera for the first time. The sliding window, genetic distance, and Ka/Ks ratio analyses indicate the purifying selection of 13 protein-coding genes, the lowest evolutionary rate of cox1, and the highest sequence variability of atp8. Considering the sufficiently large size, fast evolution, and high ratio of Ka/Ks, nad4L and nad6 are regarded as potential markers for future phylogenetic analyses, population genetics, and species delimitations in Mecoptera. The phylogenetic relationships were reconstructed for four families of Mecoptera based on all six available mitogenomes using Bayesian inference and maximum likelihood methods. The phylogeny is presented as Boreidae + (Nannochoristidae + (Bittacidae + Panorpidae)).

Ultrastructure of the vasa deferentia of Terrobittacus implicatus and Cerapanorpa nanwutaina (Insecta: Mecoptera).

The fine structures of vasa deferentia and postvesicular vasa deferentia were investigated in the hangingfly Terrobittacus implicatus (Cai et al. 2006) and the scorpionfly Cerapanorpa nanwutaina (Chou 1981) using light and transmission electron microscopy, and schematic diagrams were drawn accordingly. The vasa deferentia of both species comprise muscular layers, a basal lamina, and a mono-layered epithelium, but the postvesicular vasa deferentia contain muscular layers, a basal lamina, a single-layered epithelium, a subcuticular cavity, and an inner cuticle respectively. The vas deferens releases secretions into the lumen directly, probably by means of merocrine production. On the contrary, the cells of the postvesicular vas deferens correspond to class I glandular cells, discharging secretions into the subcuticular cavity first, and then into the lumen through an inner cuticle. The epithelium in both structures of Bittacidae is well developed and contains more microvilli, organelles, and more types of secretions than in Panorpidae. In Panorpidae, the spine of the postvesicular vas deferens may serve as a barricade for the reflow of the sperm and to protect the extraordinarily long structure from being collapsed or injured.

The scorpionflies (Mecoptera) from Lagodekhi Reserve, with some distributional and seasonal activity data.

We studied scorpionflies of Lagodekhi Reserve for the first time. Three species were recorded from the area, Panorpa similis Esben-Petersen, P. connexa McLachlan, and P. arcuata (Navás). Seasonal activity is also studied.

An enigmatic new species of Panorpa Linneaus from the Bashan Mountains (Mecoptera, Panorpidae).

A new species of Panorpidae, Panorpabashanicolasp. n., is described and illustrated from the Bashan Mountains in central China. The new species is characterized by the following characters: vertex black, with two pale longitudinal stripes and four pale rounded spots; vein 1A ending before the origin of Rs; meso- and metanotum pale, and the pale color extending to tergum III in V-shape; male epandrium emarginate distally in deep U-shape; hypovalves without basal stalk, completely represented by a pair of short hypovalves, extending to distal third of gonocoxite, with five black stout setae in distal portion; paramere simple, S-shaped; a bundle of long hairs between dorsal and ventral valves of aedeagus; dorsal valves of aedeagus much longer than ventral valves and curved ventrally, with distal portion foot-shaped; female medigynium twice as long as wide, with stout axis extending over one-third its length beyond main plate.

A chromosomal investigation of four species of Chinese Panorpidae (Insecta, Mecoptera).

The male adults of four species of the Chinese Panorpidae in Mecoptera were cytogenetically studied using conventional squashing procedures. The results show that their sex-chromosome system belongs to the XO type, with n = 19 + X(O) in Panorpa emarginata Cheng, 1949 and Panorpa dubia Chou & Wang, 1981, n = 23 + X(O) in Panorpa sp., and n = 20 + X(O) in Neopanorpa lui Chou & Ran, 1981. X chromosomes of these species usually appear dot-shaped in late prophase I and are easily differentiated from autosomal bivalents. Meiosis in these Panorpidae lacks typical diplotene and diakinesis. In late prophase I, pairs of homologous chromosomes remain parallel in a line and show no evidence of crossing-over. Some of them even appear as a single unit because of extremely intimate association, all with a tendency of increasing condensation. The evolutionary significance of their chromosomal differences and the achiasmatic meiosis of Panorpidae are briefly discussed.