Parasitic behaviour and developmental morphology of Anastatus japonicus reared on the factitious host Antheraea pernyi.

The egg parasitoid Anastatus japonicus is a key natural enemy in the biological control of various agricultural and forestry pests. It is particularly used against the brown marmorated stink bug Halyomorpha halys and the emerging defoliator pest Caligula japonica in East Asia. It has been proved that the eggs of Antheraea pernyi can be used as a factitious host for the mass production of A. japonicus. This study systematically documented the parasitic behaviour and developmental morphology exhibited by A. japonicus on the eggs of A. pernyi. The parasitic behaviour of A. japonicus encompassed ten steps including searching, antennation, locating, digging, probing, detecting, oviposition, host-feeding, grooming, and resting. Oviposition, in particular, was observed to occur in three stages, with the parasitoids releasing eggs during the second stage when the body remained relatively static. Among all the steps of parasitic behaviour, probing accounted for the longest time, constituting 33.1% of the whole time. It was followed by digging (19.3%), oviposition (18.5%), antennation (9.6%), detecting (7.4%), and the remaining steps, each occupying less than 5.0% of the total event time. The pre-emergence of adult A. japonicus involves four stages: egg (0 to 2nd day), larva (3rd to 9th day), pre-pupa (10th to 13th day), pupa (14th to 22nd day), and subsequent development into an adult. Typically, it takes 25.60 ± 0.30 days to develop from an egg to an adult at 25℃. This information increases the understanding of the biology of A. japonicus and may provide a reference for optimising reproductive devices.

The 'Goldilocks Grub': reproductive responses to leafroller host development in Goniozus jacintae, a parasitoid of the light brown apple moth.

Many parasitoids alter their reproductive behaviour in response to the quality of encountered hosts. They make adaptive decisions concerning whether to parasitise a potential host, the number of eggs laid on an accepted host, and the allocation of sex to their offspring. Here we present evidence that Goniozus jacintae Farrugia (Hymenoptera: Bethylidae), a gregarious ectoparasitoid of larval tortricids, adjusts its reproductive response to the size and developmental stage of larvae of the light brown apple moth (LBAM), Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae). Goniozus jacintae parasitises instars 3-6 of LBAM, but most readily parasitises the later, larger, instars. Brood sizes were bigger on larger hosts and brood sex ratios were female biased (proportion of males = 0.23) with extremely low variance (never >1 male in a brood at emergence), perhaps the most precise of all studied bethylids. Host size did not influence brood development time, which averaged 19.64 days, or the body size of male offspring. However, the size of females was positively correlated with host size and negatively correlated with brood size. The sizes of individual males and females were positively related to the average amount of host resource available to individuals within each brood, suggesting that adult body size is affected by scramble competition among feeding larvae. Average brood sizes were: 3rd instar host, 1.3 (SE ± 0.075); 4th instar, 2.8 (SE ± 0.18); 5th instar, 4.7 (SE ± 0.23); 6th instar, 5.4 (SE ± 0.28). The largest brood size observed was 8 individuals (7 females, 1 male) on the 6th instar of LBAM. These results suggest that later instars would give the highest yield to optimise mass-rearing of G. jacintae if used for augmentative biological pest control.

The state of parasitoid wasp genomics.

Parasitoid wasps represent a group of parasitic insects with high species diversity that have played a pivotal role in biological control and evolutionary studies. Over the past 20 years, developments in genomics have greatly enhanced our understanding of the biology of these species. Technological leaps in sequencing have facilitated the improvement of genome quality and quantity, leading to the availability of hundreds of parasitoid wasp genomes. Here, we summarize recent progress in parasitoid wasp genomics, focusing on the evolution of genome size (GS) and the genomic basis of several key traits. We also discuss the contributions of genomics in studying venom evolution and endogenization of viruses. Finally, we advocate for increased sequencing and functional research to better understand parasitoid biology and enhance biological control.

Effect of storage conditions on host egg suitability and the reproductive fitness of Oobius agrili (Hymenoptera: Encyrtidae), an egg parasitoid of the invasive emerald ash borer (Agrilus planipennis) (Coleoptera: Buprestidae).

Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae) is an important egg parasitoid of the emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae). Methods for laboratory-rearing O. agrili have been developed but its mass-production depends on the continuous production and storage of freshly laid EAB eggs as well as diapaused parasitoid progeny (inside parasitized EAB eggs). The purpose of this study was to determine optimal environmental conditions for long-term storage of host eggs as well as diapaused parasitoid progeny. Fresh host eggs and diapaused parasitoid progeny were stored at two low storage temperatures (1.7 and 12.8 °C) and three levels of relative humidity (low ~31%, medium ~74%, and high ~99.9%) for various length of time (15-270 days) and then evaluated for host egg suitability and the reproductive fitness of stored parasitoid progeny. EAB eggs were stored for approximately 30 days without significant reduction of their viability and suitability to O. agrili parasitism at low storage temperatures under high and medium relative humidity. Neither storage temperature or humidity had any significant effects on adult parasitoid emergence for storage durations of up to 270 days. When storage durations were over 120 days, however, both adult parasitoid longevity and fecundity declined approximately 20-30% across all temperature and humidity treatments. Relevance of findings to mass-production and storage of O. agrili for biocontrol is discussed.

Molecular characterisation of Australasian Ixodiphagus (Hymenoptera; Encyrtidae; Encyrtinae) reveals unexpected diversity and a potential novel host switch.

Ticks are important medical and veterinary parasites that represent a substantial health threat to humans, companion animals, and livestock. Ixodiphagus wasps (Hymenoptera; Encyrtidae) are known endoparasitoids of ixodid (hard) and argasid (soft) ticks, with potential utility as natural biocontrol agents. Two species, Ixodiphagus brunneus and Ixodiphagus mysorensis, are previously recorded from Australia, however, the genus lacks formal revisionary work in Australia, and the validity and host ranges of these species remain uncertain. This work aimed to investigate the diversity of Ixodiphagus in Australasia and provide a molecular data resource for future work on these understudied endoparasitoids. We extracted DNA from archival Ixodiphagus specimens from Australian and New Zealand insect collections and performed high-throughput sequencing which resulted in complete or mostly complete mitochondrial genome sequences from 11 specimens, including I. brunneus, Ixodiphagus taiaroaensis, and a novel Ixodiphagus sp. reared from Rhipicephalus linnaei from Townsville, Australia. In addition, approximately 70% of the genome of the Wolbachia endosymbiont of I. brunneus was recovered. Finally, we screened 178 recently collected pooled tick samples from southern New South Wales, Australia, for Ixodiphagus spp. using 28S rRNA and cytochrome c oxidase subunit 1(COI) gene PCR, and recovered 14 positive samples. Phylogenetic analysis of Australasian Ixodiphagus spp. based on 28S rRNA and complete mitochondrial genome sequences determined that members of the Australasian fauna are distinct from Ixodiphagus hookeri (the only other Ixodiphagus species for which genetic data exists), and that at least two distinct species are present in Australia; I. brunneus identified from Ixodes holocyclus and Haemaphysalis bancrofti ticks, and an uncharacterised Ixodiphagus sp. found in Rhipicephalus linnaei ticks from northern Queensland. Furthermore, there was substantial genetic diversity at the 28S rRNA loci among I. brunneus samples, which may represent normal genetic variability or a secondary cryptic species. The molecular data generated here represents the first known for the genus Ixodiphagus in Australasia, doubling that of the world fauna, and provides the first known complete mitochondrial genomes for these important tick parasitoids.

Description of a new species of Chrysonotomyia Ashmead from Houston, Texas, USA (Hymenoptera, Chalcidoidea, Eulophidae).

A new species of the genus Chrysonotomyia Ashmead, Chrysonotomyiasusbelli sp. nov., is described from the Rice University campus in Houston, Texas, USA. The species is a parasitoid emerging from Neuroterusnr.bussae galls in leaves of the southern live oak (Quercusvirginiana). This represents the 6th species described from North America north of Mexico and the first in the world known to parasitize cynipid gall wasps. This discovery hints at an entire undiscovered niche between Chrysonotomyia parasitoids, cynipid gall wasps, and oaks in the Nearctic, which is a global biodiversity hotspot for oaks and cynipids. This new species description is complemented by mtDNA-COI-barcode data and information on the natural history of this species. We record host association, phenology, and report a leaf-scanning behavior performed by females, presumably to search for host galls. Modifications to the key of New World members of the genus (Hansson 2004) are included to integrate this new species.

The Chromosome-level Genome Provides Insights into the Evolution and Adaptation of Extreme Aggression.

Extremely aggressive behavior, as the special pattern, is rare in most species and characteristic as contestants severely injured or killed ending the combat. Current studies of extreme aggression are mainly from the perspectives of behavioral ecology and evolution, while lacked the aspects of molecular evolutionary biology. Here, a high-quality chromosome-level genome of the parasitoid Anastatus disparis was provided, in which the males exhibit extreme mate-competition aggression. The integrated multiomics analysis highlighted that neurotransmitter dopamine overexpression, energy metabolism (especially from lipid), and antibacterial activity are likely major aspects of evolutionary formation and adaptation for extreme aggression in A. disparis. Conclusively, our study provided new perspectives for molecular evolutionary studies of extreme aggression as well as a valuable genomic resource in Hymenoptera.

Dickyyuellaargentinensis a tentative new genus and species of Cardiochilinae (Hymenoptera, Braconidae) from the Neotropical region.

Dickyyuella Kang & Sharkey, gen. nov. is a novel addition to the microgastroid complex of Braconidae. Taxonomic assignment within this complex posed challenges initially due to the presence of putatively plesiomorphic characters. However, closer examination revealed affiliations with the microgastroid complex, supported by morphological features such as the location of spiracles on the first metasomal tergum and the absence of spiracles on the seventh metasomal tergum. Based on the following two morphological characters, the presence of an inverted Y-shaped groove on the first metasomal tergum and pectinate tarsal claws, Dickyyuella Kang & Sharkey, gen. nov. is tentatively placed within Cardiochilinae Ashmead, 1900 despite uncertainties surrounding phylogenetic relationships. This article provides the diagnosis of Dickyyuella Kang & Sharkey, gen. nov., the description of Dickyyuellaargentinensis Kang & Sharkey, sp. nov., and a discussion of the taxonomic placement of the new genus within the microgastroid complex.

The complete mitochondrial genome and phylogenetic analysis of Cyanopterus ninghais (Hymenoptera: Braconidae).

Cyanopterus ninghais is an important gregarious ectoparasitoid during the larval stage of Monochamus alternatus, a key vector for pine wilt disease in Asia. In this study, the complete mitochondrial genome of C. ninghais was sequenced and analyzed. The mitochondrial genome of C. ninghais is 15,386 bp in length, comprising 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and 2 ribosomal RNA genes (rRNAs). The nucleotide composition is 41.32% A, 8.29% G, 6.06% C, and 44.33% T. Phylogenetic trees of Braconidae were constructed using 13 PCG sequences via Bayesian inference (BI) and maximum likelihood (ML) analyses to determine their phylogenetic position. Both ML and BI analyses revealed that C. ninghais is closely related to Euurobracon yokahamae, Virgulibracon endoxylaphagus, and Habrobracon hebetor.

A review of the genus Zygota (Hymenoptera, Diapriidae) in Germany with taxonomic notes on this genus and its distinction from Pantoclis.

This study provides a comprehensive overview of the genus Zygota Förster combining DNA barcoding and current morphology. Nineteen species of Zygota were found throughout Germany, including the newly described species Zygotawalli sp. nov. First species records for Germany are: Zygotabalteata Macek, 1997; Z.comitans Macek, 1997; Z.spinosipes (Kieffer, 1908); Z.sordida Macek, 1997; Z.angularis Macek, 1997 and Z.vigil Nixon, 1957. We also clarify diagnoses for the two related genera, Pantoclis Förster and Zygota to designate the boundaries of the Zygota genus and propose new synonymies: Zygotacaligula Buhl, 1997 is a junior synonym of Z.congener (Zetterstedt, 1840); Z.reticulata Kozlov, 1978 is a junior synonym of Z.ruficornis (Curtis, 1831). Thirteen species of Zygota sensu Nixon (1957) are transferred to the genus Pantoclis with the following new combinations proposed: Zygotabrevinervis (Kieffer, 1908) (= Pantoclisbrevinervis (Kieffer, 1909), comb. nov.); Z.brevipennis (Kieffer, 1908) (= P.brevipennis (Kieffer, 1908), comb. nov.); Z.caecutiens (Kieffer, 1908) (= P.caecutiens (Kieffer, 1908), comb. nov.); Z.cursor (Kieffer, 1908) (= P.cursor (Kieffer, 1908), comb. nov.); Z.fossulata (Thomson, 1858) (=P.fossulata (Thomson, 1858), comb. nov.); Z.fuscata (Thomson, 1858) (= P.fuscata (Thomson, 1858), comb. nov.); Z.hemiptera (Thomson, 1858) (= P.hemiptera (Thomson, 1858), comb. nov.); Z.microtoma (Kieffer, 1909) (= P.microtoma (Kieffer, 1909), comb. nov.); Z.soluta (Kieffer, 1907) (= P.soluta (Kieffer, 1907), comb. nov.); Z.striata (Kieffer, 1909) (= P.striata (Kieffer, 1909), comb. nov.); Z.subaptera (Thomson, 1858) (= P.subaptera (Thomson, 1858), comb. nov.); Z.sulciventris (Kieffer, 1909) (= P.sulciventris (Kieffer, 1909), comb. nov.), and Z.unicolor (Kieffer, 1908) (= P.unicolor (Kieffer, 1908), comb. nov.).