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The species belonging to Sclerodermus (Hymenoptera: Bethylidae) are currently the most important insect natural enemies of wood borer pests, mainly buprestid and cerambycid beetles, in China. However, some sibling species of this genus are very difficult to distinguish because of their similar morphological features. To address this issue, we conducted phylogenetic and genetic analyses of cytochrome oxidase subunit I (COI) and 28S RNA gene sequences from eight species of Sclerodermus reared from different wood borer pests. The eight sibling species were as follows: S. guani Xiao et Wu, S. sichuanensis Xiao, S. pupariae Yang et Yao, and Sclerodermus spp. (Nos. 1-5). A 594-bp fragment of COI and 750-bp fragment of 28S were subsequently sequenced. For COI, the G-C content was found to be low in all the species, averaging to about 30.0%. Sequence divergences (Kimura-2-parameter distances) between congeneric species averaged to 4.5%, and intraspecific divergences averaged to about 0.09%. Further, the maximum sequence divergences between congeneric species and Sclerodermus sp. (No. 5) averaged to about 16.5%. All 136 samples analyzed were included in six reciprocally monophyletic clades in the COI neighbor-joining (NJ) tree. The NJ tree inferred from the 28S rRNA sequence yielded almost identical results, but the samples from S. guani, S. sichuanensis, S. pupariae, and Sclerodermus spp. (Nos. 1-4) clustered together and only Sclerodermus sp. (No. 5) clustered separately. Our findings indicate that the standard barcode region of COI can be efficiently used to distinguish morphologically similar Sclerodermus species. Further, we speculate that Sclerodermus sp. (No. 5) might be a new species of Sclerodermus.

Some authors in the past based their conclusions about the limits of the metapostnotum of Chrysidoidea based on the position of the mesophragmo-metaphragmal muscle, rather than aspects of the skeleton and musculature associated with the metapectal-propodeal complex. The latter character system suggests another interpretation of the metapostnotum delimitation. Given this scenario, the main goal of this work is to present a new perspective on the metapostnotum in Chrysidoidea, especially Bethylidae, helping to resolve questions related to the evolution of the metapostnotum. This is based on homologies established by associating of insertion points of ph2-ph3 and ph3-T2 muscles with the delimitation of the respective sclerite the muscles insert into. Our results indicate that, according the position of the metaphragmal muscles, the metapostnotum in Bethylidae is medially expanded in the propodeal disc and has different forms of configuration. Internally, the limits of the metapostnotum can be tracked by the shape of the mesopostnotum, and vice versa. Thus, the anteromedian area of the propodeal disc sensu Evans was reinterpreted in the current study as the metapostnotum. In conjunction with associated structures, we provide evidence to clarify the relationships between the families within Chrysidoidea, although certain families like Embolemidae, Dryinidae and Chrysididae exhibit extreme modifications of the condition found in Aculeata, as observed in Bethylidae. We review the terminology used to describe anatomical features on the metapectal-propodeal complex in Bethylidae in general, and provide a list of recommended terms in accordance with the online Hymenoptera Anatomy Ontology. The morphology of the studied subfamilies are illustrated. Studies that focus on a single structure, across a larger number of taxa, are more insightful and present specific questions that can contribute to broader issues, thus providing a better understanding of the morphology and evolution of insects.

The relationship between body size and fitness in parasitoid wasps has several effects on parasitic ability, reproductive behavior in female wasps, and progeny fitness. Female wasps with various body sizes were obtained by mass-rearing a gregarious ectoparasitoid, Sclerodermus pupariae, which is one of the excellent parasites to control the larvae and pupae of Buprestidae and Cerambycidae. We investigated the effects of body size of adult females introduced on Thyestilla gebleri (Coleoptera: Cerambycidae) larvae on their paralysis time, pre-oviposition period, oviposition period and fecundity, and the related fitness of their offspring. Results showed that small female wasps needed more time to paralyze a host and had a higher mortality rate than large female wasps. More offspring were produced by large female wasps than by small female wasps, and the percentage and body size of female offspring was not affected by maternal body size. The duration of the egg stage was not affected by foundress size, nor was that of the pupal stage, but the duration of the larval stage and generation time of small female wasps was longer than that of large females. Our findings suggest that the parasitic fitness and offspring performance are affected by maternal size, and there is need to choose reasonable body size of female wasps, to optimally utilize mass rearing and to control target pests with the lowest mortality cost.

The genus Caloapenesia, only known from the Oriental region, comprises nineteen species, seventeen of which are recorded from Thailand and the Philippines, countries adjacent to China. During our examination of bethylid specimens from southern China, we discovered Caloapenesia xui sp. nov. from Guangdong Province, representing the northernmost record for the genus. The new species is described and illustrated, and an updated key to the males of Caloapenesia is provided.

Some authors in the past based their conclusions about the limits of the metapostnotum of Chrysidoidea based on the position of the mesophragmo-metaphragmal muscle, rather than aspects of the skeleton and musculature associated with the metapectal-propodeal complex. The latter character system suggests another interpretation of the metapostnotum delimitation. Given this scenario, the main goal of this work is to present a new perspective on the metapostnotum in Chrysidoidea, especially Bethylidae, helping to resolve questions related to the evolution of the metapostnotum. This is based on homologies established by associating of insertion points of ph2-ph3 and ph3-T2 muscles with the delimitation of the respective sclerite the muscles insert into. Our results indicate that, according the position of the metaphragmal muscles, the metapostnotum in Bethylidae is medially expanded in the propodeal disc and has different forms of configuration. Internally, the limits of the metapostnotum can be tracked by the shape of the mesopostnotum, and vice versa. Thus, the anteromedian area of the propodeal disc sensu Evans was reinterpreted in the current study as the metapostnotum. In conjunction with associated structures, we provide evidence to clarify the relationships between the families within Chrysidoidea, although certain families like Embolemidae, Dryinidae and Chrysididae exhibit extreme modifications of the condition found in Aculeata, as observed in Bethylidae. We review the terminology used to describe anatomical features on the metapectal-propodeal complex in Bethylidae in general, and provide a list of recommended terms in accordance with the online Hymenoptera Anatomy Ontology. The morphology of the studied subfamilies are illustrated. Studies that focus on a single structure, across a larger number of taxa, are more insightful and present specific questions that can contribute to broader issues, thus providing a better understanding of the morphology and evolution of insects.

The genus Sclerodermus Latreille (Hymenoptera: Bethylidae) comprises over 80 species of ectoparasitoids of insect pests in forests, agricultural environments, and stored products with a cosmopolitan distribution. Despite its growing significance in biological control, behavioral ecology, and public health, the taxonomy of the genus remains poorly resolved. This is largely due to morphological reduction and simplification among species, outdated or incomplete original descriptions, and limited access to type material. A particularly problematic case is Sclerodermus cereicollis Kieffer, originally described from two geographically disjunct populations: Giglio Island (Italy, Palaearctic) and Annobón Island (Equatorial Guinea, Afrotropical). The syntype series includes morphologically divergent specimens, casting doubt on their conspecificity. In this study, we redescribe S. cereicollis based on both the original syntypes and newly collected material from Italy. A lectotype is designated to stabilize the nomenclature, and we provide the first molecular data for the species to assess genetic cohesion among populations. Comparative morphological and molecular analyses reveal that the Afrotropical syntypes represent a distinct, previously undescribed species. Accordingly, we describe Sclerodermus annobonensis Masini, Colombo & Azevedo sp. nov., designating a holotype. This study refines species boundaries within Sclerodermus and highlights the value of integrative taxonomy, combining historical and contemporary data, in resolving persistent systematic ambiguities in morphologically conservative taxa.

We describe and illustrate Goniozus apoderophagus Gupta & Azevedo n. sp. (Hymenoptera, Bethylidae), an ectoparasitoid of Apoderus tranquebaricus Fabricius (Coleoptera, Attelabidae) associated with leaf rolls of Grewia abutilifolia Vent. ex Juss. from Karnataka, India. The new species is compared with all the possible closely allied species from the Oriental region.

Asian longhorned beetle, Anoplophora glabripennis (Motschulsky), is a high-risk invasive forest pest worldwide. We surveyed Asian longhorned beetle parasitoid guilds and their seasonal abundance using field-deployed sentinel host logs infested with Asian longhorned beetle eggs or newly hatched (early-instar) larvae in three different sites of China (Beijing City, Shanghai City, and Jilin Province) from 2015 to 2018. Our survey detected 12 species of hymenopteran parasitoids (four Pteromalidae, three Braconidae, two Eupelmidae, one Eurytomidae, one Ichneumonidae, and one Bethylidae) attacking sentinel Asian longhorned beetle larvae or eggs deployed in these sites. Total parasitism by all the parasitoid species varied with different sites and across different years of the survey (averaging 7–16% in Beijing, 4–11% in Shanghai, and 0–0.2% in Jilin Province). In addition, the seasonal pattern of parasitism also differed among different sites, with parasitism peaking in July in the northern site (Beijing, 19%) and June in the southern site (Shanghai, 16%). Among all the parasitoid species recovered, Oxysychus sp. (Hymenoptera: Pteromalidae) was the most abundant parasitoid species in both Beijing and Shanghai (with 42–66% relative abundance and an average of 6% Asian longhorned beetle parasitism). The second most abundant species was Bracon planitibiae Yang, Cao et Gould (Hymenoptera: Braconidae), which accounted for 35% of the species collected and caused an average of 5% Asian longhorned beetle parasitism. Relevance of our findings to Asian longhorned beetle biocontrol is discussed.

Sclerodermus guani Xiao et Wu, Sclerodermus sichuanensis Xiao, Sclerodermus pupariae Yang et Yao, and Sclerodermus alternatusi Yang are four species of Sclerodermus that have been found in China on longhorn or buprestid beetle hosts. These parasitoids are of great importance to forest management because they control certain forest pests. Knowledge of their developmental differences is important for maximizing their use in bio-control programs, yet little about them is known. This study compared their number of offspring and developmental biology. There were significant differences in the four parasitoids’ egg, larval, pupal, and total developmental stages. The F2 male offspring of each parasitoid emerged approximately one day ahead of the female. Additionally, there were differences in the number of F2 male and female offspring, as well as in the sex percentage, among the four parasitoids. Compared to the other three wasps, S. alternatusi had a significantly lower F2 female percentage of 67.07%, which was notably less than that of the other wasps (over 90%). The total F2 offspring number and F2 female offspring number of S. guani were the greatest. Sclerodermus alteratusi produced a larger percentage of winged females (5.66%) compared to S. pupariae (3.98%), and no winged females developed from S. guani or S. sichuanensis. Almost all individuals survived the 30-day experiment, the survival rate decreased to about half after 120 days at 12 °C, and there was no difference between the species. The biological differences between the four wasp species analyzed in this study will help improve the effectiveness of mass-rearing them for the biological control of forest pests.

The genus Laelius Ashmead, 1893 (Hymenoptera, Bethylidae) is a cosmopolitan bethylid genus with 68 valid species distributed across most zoogeographic regions worldwide. This taxonomic study on Korean species of Laelius has led to the description of four new species, namely L. afores sp. nov. , L. atratus sp. nov. , L. sulcatus sp. nov. , and L. tricuspis sp. nov. Additionally, illustrations of the diagnostic characteristics of each species are provided, along with an updated key for 11 Laelius species from the Eastern Palaearctic region.