The Chalcidoidea bush of life: evolutionary history of a massive radiation of minute wasps

A new species of Proaphelinoides Girault (Hymenoptera, Aphelinidae) from China, with a phylogenetic analysis

A new species of Proaphelinoides Girault, Proaphelinoideshuangi Chen & Jiang, sp. nov., is reported from China. A key to all species of the genus is provided. DNA standard barcode COI and partial nuclear ribosomal 28S-D2 from two individuals of Proaphelinoides were sequenced, and 28S-D2 rDNA was included in a phylogenetic analysis, confirming Proaphelinoides as the sister group to Aphytis.

Parasitoid speciation and diversification

Parasitoid wasps may well be the most species-rich animal group on Earth, and host-parasitoid interactions may thereby be one of the most common types of species interactions. Understanding the major mechanisms underlying diversification in parasitoids should be a high priority, not the least in order to predict consequences from high extinction rates currently observed. The two major hypotheses explaining host-associated diversification are the escape-and-radiate hypothesis and the oscillation hypothesis, where the former assumes that key innovations are major drivers of radiation bursts, whereas the latter rather assumes that diversification depends on processes acting on the standing genetic variation that influences host use. This paper reviews the recent literature on parasitoid speciation in light of these major hypotheses to identify potential key innovations and host use variability underlying diversification. The paper also calls upon recent theoretical advances from a similar system, plant-butterfly interactions, to provide shortcuts in the development of theories explaining the high diversity of parasitoid wasps.

Review of Asaphes Walker, 1834 (Hymenoptera, Chalcidoidea, Asaphesinae) from Xinjiang, China

Four species of the cosmopolitan genus Asaphes Walker, 1834 (Hymenoptera: Chalcidoidea: Asaphesinae, family incerta sedis) are recorded from Xinjiang Uyghur Autonomous Region, China, bringing the number of known species in China to eight. In addition to Asaphessuspensus (Nees ab Esenbeck), 1834 and A.vulgaris Walker, 1834, A.fuyunis Li & Zhang, sp. nov. is newly described based on females and A.californicus Girault, 1917, previously known only from North and South America, is newly recorded from China. These four species are differentiated using an integrative taxonomic approach that includes COI barcode data and morphometrics, and are illustrated using macrophotography. Additionally, the 13 described world species of Asaphes are tabulated and females of the eight recognized Chinese species are keyed.

Phylogenomics and biogeography of sawflies and woodwasps (Hymenoptera, Symphyta)

Phylogenomic approaches have recently helped elucidate various insect relationships, but large-scale comprehensive analyses on relationships within sawflies and woodwasps are still lacking. Here, we infer the relationships and long-term biogeographic history of these hymenopteran groups using a large dataset of 354 UCE loci collected from 385 species that represent all major lineages. Early Hymenoptera started diversifying during the Early Triassic ∼249 Ma and spread all over the ancient supercontinent Pangaea. We recovered Xyeloidea as a monophyletic sister group to other Hymenoptera and Pamphilioidea as sister to Unicalcarida. Within the diverse family Tenthredinidae, our taxonomically and geographically expanded taxon sampling highlights the non-monophyly of several traditionally defined subfamilies. In addition, the recent removal of Athalia and related genera from the Tenthredinidae into the separate family Athaliidae is supported. The deep historical biogeography of the group is characterised by independent dispersals and re-colonisations between the northern (Laurasia) and southern (Gondwana) palaeocontinents. The breakup of these landmasses led to ancient vicariance in several Gondwanan lineages, while interchange across the Northern Hemisphere has continued until the Recent. The little-studied African sawfly fauna is likewise a diverse mixture of groups with varying routes of colonization. Our results reveal interesting parallels in the evolution and biogeography of early hymenopterans and other ancient insect groups.

Orthoptera-specific target enrichment (OR-TE) probes resolve relationships over broad phylogenetic scales

Phylogenomic data are revolutionizing the field of insect phylogenetics. One of the most tenable and cost-effective methods of generating phylogenomic data is target enrichment, which has resulted in novel phylogenetic hypotheses and revealed new insights into insect evolution. Orthoptera is the most diverse insect order within polyneoptera and includes many evolutionarily and ecologically interesting species. Still, the order as a whole has lagged behind other major insect orders in terms of transitioning to phylogenomics. In this study, we developed an Orthoptera-specific target enrichment (OR-TE) probe set from 80 transcriptomes across Orthoptera. The probe set targets 1828 loci from genes exhibiting a wide range of evolutionary rates. The utility of this new probe set was validated by generating phylogenomic data from 36 orthopteran species that had not previously been subjected to phylogenomic studies. The OR-TE probe set captured an average of 1037 loci across the tested taxa, resolving relationships across broad phylogenetic scales. Our detailed documentation of the probe design and bioinformatics process is intended to facilitate the widespread adoption of this tool.

Highlighting overlooked biodiversity through online platforms: The "Chalcid Wasps of Cyprus" website

Biodiversity data platforms including databases, websites and data repositories underpin conservation efforts by collecting spatiotemporal data of discovered native and alien species and maps of their distributions. Chalcid wasps (Hymenoptera, Chalcidoidea) are one of the most diverse insect groups estimated to include half a million species. Being mostly parasitoids of other arthropods, they have been successfully used as biological control agents against serious agricultural pests worldwide. In Cyprus, only 124 species of chalcid wasps have been recorded, with 53 species being alien to the island. Their true biodiversity is predicted to be much larger because the island is both under-sampled and under-researched. A number of biodiversity data platforms focusing on the biodiversity of Cyprus are currently online; however, an online platform dedicated on the chalcid wasps of Cyprus is lacking. In the framework of the Darwin Plus Fellowship (DPLUS202) "Species richness and biological invasions of Chalcid wasps in Akrotiri Peninsula", the "Chalcid wasps of Cyprus" website (https://sites.google.com/view/chalcidwaspscyprus) is presented. This online, dynamic database aims to: (1) raise public awareness regarding a rather neglected and yet ecologically important insect group, (2) provide data on the morphology, ecology and biodiversity of Chalcidoidea on Cyprus, as well as (3) promote conservation needs by setting a baseline for the future assessment of both native and alien chalcid wasp species. This online platform will be regularly revised in order to provide an up-to-date, user-friendly digital environment to the scientific community, policy-makers and citizens.

The genome sequence of the chalcid wasp, Chalcis sispes Linnaeus, 1761

We present a genome assembly from an individual female Chalcis sispes (chalcid wasp; Arthropoda; Insecta; Hymenoptera; Chalcididae). The genome sequence is 412.4 megabases in span. Most of the assembly is scaffolded into 6 chromosomal pseudomolecules. The mitochondrial genome has also been assembled and is 15.9 kilobases in length.

The first two complete mitochondrial genomes for the genus Anagyrus (Hymenoptera, Encyrtidae) and their phylogenetic implications

Anagyrus, a genus of Encyrtidae (Hymenoptera, Chalcidoidea), represents a successful group of parasitoid insects that attack various mealybug pests of agricultural and forestry plants. Until now, only 20 complete mitochondrial genomes have been sequenced, including those in this study. To enrich the diversity of mitochondrial genomes in Encyrtidae and to gain insights into their phylogenetic relationships, the mitochondrial genomes of two species of Anagyrus were sequenced, and the mitochondrial genomes of these species were compared and analyzed. Encyrtid mitochondrial genomes exhibit similarities in nucleotide composition, gene organization, and control region patterns. Comparative analysis of protein-coding genes revealed varying molecular evolutionary rates among different genes, with six genes (ATP8, ND2, ND4L, ND6, ND4 and ND5) showing higher rates than others. A phylogenetic analysis based on mitochondrial genome sequences supports the monophyly of Encyrtidae; however, the two subfamilies, Encyrtinae and Tetracneminae, are non-monophyletic. This study provides valuable insights into the phylogenetic relationships within the Encyrtidae and underscores the utility of mitochondrial genomes in the systematics of this family.

One Step beyond Species Description: Unveiling a Fine-Scale Diversity within the Genus Dzhanokmenia Kostjukov (Hymenoptera: Eulophidae)

Although Chalcidoidea is one of the megadiverse superfamilies in Hymenoptera, numerous species are still being discovered and described. However, the difficulties in delimiting intra- and interspecific variation hinder this process. In this study, DNA barcoding methods using the COI gene were employed to investigate the morphological variation within Dzhanokmenia Kostjukov, 1977. The nuclear locus, 28S D2, was used to infer a phylogeny to gain an understanding of the relationship of Dzhanokmenia with other potentially close genera. Through a preliminary DNA barcode library established here, including eight species, we calibrated the intraspecific variation in certain diagnostic characters for the new species described here, D. brevifunis Ganbaatar & Cao sp. nov. Maximum likelihood results show that Dzhanokmenia is clustered with the genera associated with Tetrastichus, such as Chaenotetrastichus Graham, 1987, Baryscapus Förster, 1856, Tetrastichus Haliday, 1844, and Oomyzus Rondani, 1870 involved in this study. Our results indicate that the species diversity of Dzhanokmenia is understudied and tentatively confirm that Dzhanokmenia has a potential close relationship with Baryscapus. Along with the DNA barcode library, the referenced phylogeny datasets improve the understanding of the systematic position of Dzhanokmenia within the subfamily Tetrastichinae and the definition of this genus in terms of morphology, thereby facilitating species delimitation, discovery, and description within Dzhanokmenia.

Small wasps, big muscles: Fore and hind leg modifications in chalcidoid wasps (Hymenoptera: Chalcidoidea)

A particularly conspicuous morphological feature in chalcidoid wasps are strikingly modified legs present in both males and females. It evolved convergently multiple times on either fore or hind legs implying strong evolutionary pressure and a prominent function in the wasps' life history. We investigate the external and internal morphology of the modified legs of five species of chalcidoid wasps representing four families (Ooderidae, Heydeniidae, Chalcididae, and Leucospidae), using light microscopy, scanning electron microscopy and micro computed tomography. We aimed to identify shared characteristics as well as differences between genera/species, leg pairs and sexes and to draw first conclusions about the shared or different functions. All species and sexes share the same general leg morphology, with enlarged femur, curved tibia and a huge flexor tibiae muscle. However, there are also genus/species-specific differences such as distinctive spine-like setae on the femur of Oodera spp., or leg pair-specific differences in the position of the extensor tibiae muscle. Shared characteristics imply a common primary function in which strong forces are required to pull the tibia against the femur while differences imply different secondary functions. Both primary and secondary functions have yet to be revealed beyond informed speculations.

Helenus and Ajax, Two Groups of Non-Autonomous LTR Retrotransposons, Represent a New Type of Small RNA Gene-Derived Mobile Elements

Terminal repeat retrotransposons in miniature (TRIMs) are short non-autonomous long terminal repeat (LTR) retrotransposons found from various eukaryotes. Cassandra is a unique TRIM lineage which contains a 5S rRNA-derived sequence in its LTRs. Here, two new groups of TRIMs, designated Helenus and Ajax, are reported based on bioinformatics analysis and the usage of Repbase. Helenus is found from fungi, animals, and plants, and its LTRs contain a tRNA-like sequence. It includes two LTRs and between them, a primer-binding site (PBS) and polypurine tract (PPT) exist. Fungal and plant Helenus generate 5 bp target site duplications (TSDs) upon integration, while animal Helenus generates 4 bp TSDs. Ajax includes a 5S rRNA-derived sequence in its LTR and is found from two nemertean genomes. Ajax generates 5 bp TSDs upon integration. These results suggest that despite their unique promoters, Helenus and Ajax are TRIMs whose transposition is dependent on autonomous LTR retrotransposon. These TRIMs can originate through an insertion of SINE in an LTR of TRIM. The discovery of Helenus and Ajax suggests the presence of TRIMs with a promoter for RNA polymerase III derived from a small RNA gene, which is here collectively termed TRIMp3.

New genera of Afrotropical Chalcidoidea (Hymenoptera: Cerocephalidae, Epichrysomallidae, Pirenidae and Pteromalidae)

As a preliminary step towards the development of a key to genera of several families of Afrotropical Chalcidoidea, seven new genera in four families are described: Cerocephalidae-Milokoa Mitroiu, gen. nov. (type species: Milokoa villemantae Mitroiu, sp. nov.); Epichrysomallidae-Delvareus Rasplus, Mitroiu & van Noort, gen. nov. (type species: Delvareus dicranostylae Rasplus, Mitroiu & van Noort, sp. nov.); Pirenidae-Afrothopus Mitroiu, gen. nov. (type species: Afrothopus georgei Mitroiu, sp. nov.); Pteromalidae-Kerangania Mitroiu, gen. nov. (type species: Kerangania nuda Mitroiu, sp. nov.), Pilosalis Mitroiu, Rasplus & van Noort, gen. nov. (type species: Pilosalis barbatulus Mitroiu, sp. nov.), Scrobesia Mitroiu & Rasplus, gen. nov. (type species: Scrobesia acutigaster Mitroiu & Rasplus, sp. nov.), and Spiniclava Mitroiu & Rasplus, gen. nov. (type species: Spiniclava baaiensis Mitroiu & Rasplus, sp. nov.). Additionally, the following new species are described: Pilosalis bouceki Mitroiu & Rasplus, sp. nov., Pilosalis eurys Mitroiu & van Noort, sp. nov., Pilosalis minutus Mitroiu, sp. nov., Pilosalis platyscapus Mitroiu, Rasplus & van Noort, sp. nov., Scrobesia pondo Mitroiu, sp. nov., and Spiniclava setosa Mitroiu, sp. nov. All taxa are illustrated and the relationships with similar taxa are discussed. For each non-monotypic genus a key to species is provided.

A new genus and species of Encyrtidae (Hymenoptera: Chalcidoidea) with a four-segmented funicle from late Eocene Baltic amber

Electrocerus brevifuniculatus Simutnik gen.etsp. nov. is described and illustrated based on a female specimen from late Eocene Baltic amber. Placement of the new genus in the subfamily Encyrtinae is supported by the presence of a filum spinosum on the linea calva and the hypopygium not reaching the metasomal apex. A key to the genera of late Eocene Encyrtinae is provided. The new taxon differs from all known extinct and most extant encyrtids by its four-segmented female funicle.

Exploration for Asian longhorned beetle parasitoids in Korea using an improved sentinel log trap

The Asian longhorned beetle (ALB), Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), is a destructive invasive woodboring insect pest, and efforts are being made to find parasitoids for ALB biological control. Through a four-year survey in Korea using a sentinel log trap associated with host chemical cues potentially important for host finding by parasitoids, two parasitoid species were discovered attacking ALB. One species is Spathius ibarakius Belokobylskij & Maetô, which is known to also parasitize citrus longhorned beetle, Anoplophora chinensis (Forster). The other parasitoid species, whose offspring were dead before imago, could not be morphologically identified at the adult stage. We attempted molecular and morphological identification of the larvae/pupae of the unidentified parasitoid; however, only superfamily-level identification was possible. The parasitism rate recovered in the logs was 0.3% by the unidentified parasitoid in Gapyeong-gun in 2019, while it reached 29.2% by S. ibarakius in Busan city in 2022. Future efforts for exploring ALB natural enemies in the pest's native range may focus on parasitoids with high parasitism rates.