Cynipidae Research Articles

Description of Neuroandricus a new genus of gall wasp (Hym.: Cynipidae) and a new species of associated Sycophila (Hym.: Eurytomidae)

A new genus of oak gall wasps, Neuroandricus Pujade-Villar & Melika, gen. nov., with one new species, N. pustulatus Pujade-Villar & Melika, sp. nov. is described from Mexico. The new Cynipini species is known from its asexual generation which induces galls on leaves of Quercus (section Quercus). Also, a new species of gall-associated parasitoid is described, Sycophila baldufi Savall-Roig & Pujade-Villar, sp. nov. (Eurytomidae), emerged from N. pustulatus galls. Diagnosis, distribution and biological data of the new species are given.

New herb gall wasps (Hymenoptera: Cynipidae: Aulacideini) from Kyrgyzstan, with description of a new genus and a review of the genus Panteliella Kieffer, 1901

We describe three new aulacideine herb gall wasp species (Hymenoptera: Cynipidae: Aulacideini) from Kyrgyzstan, a country from which only two Aulacideini species were previously known. One of our new species represents a new genus, which we describe here as Soparia oshensis Nastasi gen. and sp. nov. We describe Panteliella rugosa Nastasi sp. nov., representing a new genus record for Kyrgyzstan. To further facilitate species recognition in Panteliella, we redescribe the genus and the species P. fedtschenkoi; provide a translated description of P. bianchii Vyrzhikovskaya, 1962; comment on complications affecting this genus; and provide a key to Panteliella species. Lastly, we describe Isocolus barakus Nastasi sp. nov., a species with morphology atypical of Isocolus. We provide a key to the Kyrgyz genera of Aulacideini to ensure that they remain diagnosable for future study. Our findings illustrate the continued unveiling of a diverse herb cynipid fauna in Central Asia and a need for further taxonomic study in the region.

The Gall Wasp Ophelimus migdanorum and Its Parasitoid Closterocerus chamaeleon on Eucalyptus globulus at Two Sites with Different Rainfall Parameters in Bogotá, Colombia.

As a pest, the gall wasp Ophelimus migdanorum poses a risk to several Eucalyptus species in Colombia. In the tropical Andes, its biological development and the damage it causes can be influenced by climate, particularly rainfall. In this regard, we examined gall phenology, population fluctuation, and leaf damage caused by O. migdanorum, and its parasitoid Closterocerus chamaeleon, over 5months at two sites with contrasting rainfall in peri-urban areas of Bogotá, Colombia. Gall phenology and foliar damage were assessed on 10 trees per site. We characterized gall phenology by assessing their size and color, wasps' developmental stages, as well as affected leaf area and gall density on the leaf blade. Additionally, the individuals found in five attraction traps at each site were quantified biweekly to record population fluctuations. The effect of rainfall on wasp frequency and gall density between sampling sites and dates was compared using the chi-square test, while the relationship with rainfall was evaluated using the Kruskal-Wallis test. Only females of the gall wasp and its parasitoid were observed during the study, displaying multivoltine behavior. Six developmental stages of the galls were differentiated, each characterized by distinct coloration. Drier microclimates favored gall size, wasps' development stage frequency, population trend, and foliar damage. The general trend indicated a greater abundance of the parasitoid C. chamaeleon compared to O. migdanorum. Our study suggests that O. migdanorum has a less damaging effect on E. globulus in areas with rainy microclimates.

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.

Interactions between invasive pests and pathogens in a native chestnut forest

The introduction in the same area of different invasive species can result in novel interactions, with unpredictable consequences. We carried out a study in Galicia (northwestern Iberian Peninsula) with the aim of clarifying the interactions between two invasive species Cryphonectria parasitica and Dryocosmus kuriphilus. In 2018, we selected five chestnut plots affected by both species. We compared trees affected only by the insect and trees affected by both the insect and the fungus with respect to attack level, gall characteristics, female size and fecundity, and concentrations of nitrogen, water and secondary metabolites. We also evaluated female preferences in a greenhouse assay. There were higher levels of attack in trees affected by both invaders. However, the greenhouse assay showed that ovipositing females do not preferentially choose trees attacked by the fungus. The presence of the fungus had no effect on the size, wall thickness, or hardness of D. kuriphilus galls, but larvae were smaller in trees also affected by the fungus. The fecundity of females was strongly related to the presence of chestnut blight; the number of eggs per female was almost double in trees affected by the fungus. There were no relations between blight and the nitrogen or water content in the galls, where the insects feed. There were also no effects of chestnut blight on the concentration of terpenes or phenols, but condensed tannins were higher in trees with chestnut blight. The higher tannins induced by chestnut blight may directly or indirectly benefit gall wasps. Positive relationships between condensed tannin concentration and reproductive performance of other gall makers were previously reported. Tannins can also improve the negative effects of environmental conditions inside the gall. Our results indicate that the presence of chestnut blight can increase the suitability of chestnut trees for the invasive insect, D. kuriphilus, through the increase in tannins due to the presence of the fungus.

Chromosome-level genome assembly of Oriental chestnut gall wasp (Dryocosmus kuriphilus)

Dryocosmus kuriphilus, commonly known as the chestnut gall wasp, belongs to the family Cynipidae and is native to China. It is a highly invasive insect species causing serious damage to chestnut trees and has rapidly spread to various continents, including Europe, North America, and Oceania. The D. kuriphilus has become one of the important pests of chestnut plants in the world and is listed as a quarantine object by the European and Mediterranean Plant Protection Organization (EPPO). In this study, we used PacBio long reads, Illumina short reads, and Hi-C sequencing data to construct a chromosome-level assembly of the D. kuriphilus genome. The assembled genome includes 14,729 contigs with a total length of 2.28 Gb and a contig N50 of 0.8 Mb. With Hi-C technology, 2.17 Gb (95.02%) of contigs were anchored and oriented into the 10 pseudochromosomes with the scaffold N50 of 198.8 Mb and the scaffold N90 of 158.8 Mb. In total, 24,086 protein-coding genes were predicted in the assembled D. kuriphilus genome as the reference gene set. A total of 1.82 Gb repeats (occupying 79.7% of the genome), including 1.42 Gb of transposable elements and 0.40 Gb of tandem repeats, were identified in D. kuriphilus genome. In the evaluation of completeness, the BUSCO analysis determined a level of 98.1% completeness for the assembled genome sequences based on the Insecta database (OrthoDB version 10). The high-quality genome assembly of D. kuriphilus will not only provide a valuable reference for the study of its evolutionary history and genetic structure but also facilitate the research of host-pest interactions and invasiveness. Moreover, this genome assembly will promote in the development of effective management strategies to mitigate the economic and ecological impacts of this invasive pest on chestnut trees and ecosystems.

Phenological alignment of a galling insect used as biocontrol agent for an invasive tree following hemisphere translocation

Acacia longifolia is one of the most widespread invasive alien plant species along coastal areas in Portugal. In South Africa, this species is also invasive and has been controlled for over 40 years by the Australian gall wasp Trichilogaster acaciaelongifoliae. This biological control agent was introduced in Portugal in 2015, being released immediately after import, i.e., without a laboratory rearing period to adjust the life cycle, and is now established in many locations along the coast. When released in the northern hemisphere, the agent came from the austral spring, with the host-plants having tiny buds, and faced boreal winter with host-plants having large buds. As such it had to synchronize its life cycle with the seasons and phenology of the host-plant in this new location. Both locations have mild summer Mediterranean climates. The present work aims to better understand the life cycle of T. acaciaelongifoliae in the northern hemisphere and how it has aligned its phenology to these new conditions, namely different host-plant phenology and seasons. Two sites were selected (Pataias and São Jacinto), and monitored monthly, from November 2021 to October 2022, to: i) describe the early stages of the life cycle, since oviposition, by collecting and dissecting A. longifolia buds of 5 branches/five trees/site; ii) characterize the stages of the life cycle of T. acaciaelongifoliae inside the developing galls, by collecting and analysing 50 galls/site; and iii) monitoring the development of galls on 10 A. longifolia marked branches/ five trees, in the field. The results suggest that T. acaciaelongifoliae in the northern hemisphere has a univoltine life cycle, but the generations are not completely synchronized at the two sites and even within each site. It is not excluded that two generations may occur throughout the year, i.e., a bivoltine cycle, in some individuals. The alignment of the life cycle may not yet be stabilized. The life cycle seems to be more advanced in the site located further south, Pataias, where adults emerged earlier. Reproductive galls dominated in almost all months, as in South Africa. The present work advances the knowledge on the life cycle of T. acaciaelongifoliae, especially in the northern hemisphere, providing details about the timings and duration of each life cycle stage in this new location. These results are relevant for the management of A. longifolia, stressing the plasticity of the agent life cycle which can facilitate the planning of the biocontrol agent releases in new locations.

Aulacidea manchuria Nastasi sp. nov., a new herb gall wasp from China (Hymenoptera: Cynipoidea: Aulacideini), with commentary on hawkweed (Asteraceae: Hieraciinae) gall wasps

We describe Aulacidea manchuria Nastasi sp. nov., a new species of herb gall wasp from China and the second species of Aulacidea Ashmead, 1897 to be described from the country. Based on morphological data, A. manchuria belongs to the Aulacidea hieracii group, which is known to induce galls on the stems, leaves, and stolons of Hieracium L. and Pilosella Hill; we provide a key to Eastern Palearctic females of this species group to better enable identification of these species. We discuss records of herb gall wasps from China, the recognition of hawkweed gall wasp species, and further issues with taxonomy of this species group and of Aulacidea.

Galling by Trichilogaster sp. suppresses the growth of Acacia auriculiformis saplings

Pre-release efficacy assessments (PREAs) are used in weed biological control to predict the potential impact of prospective agents. These assessments enable the most damaging agents to be prioritised for host testing and release. Further, the inclusion of this information in release applications enables regulators to consider the benefits of an agent alongside any risks. We conducted a PREA to evaluate the efficacy of Trichilogaster sp., a galling wasp that is being considered for release in Florida to control invasive earleaf acacia, Acacia auriculiformis. This species is multivoltine and primarily galls vegetative buds. We performed a glasshouse trial exposing A. auriculiformis saplings to one generation of the gall wasp to determine the effect of galling on plant performance. We monitored the growth parameters and development of exposed and unexposed saplings every three weeks for twelve weeks. Above-ground and below-ground biomass were measured at the completion of the trial. One generation of galling reduced sapling height by 37.44 % (±5.57), above-ground biomass by 32.19 % (±4.00), and below-ground biomass by 38.26 % (±7.47). Galling also significantly reduced the other key growth parameters of stem weight, leaf weight, total branch length, and the number of nodes, shoot tips, and leaves. This Trichilogaster species significantly damages juvenile A. auriculiformis plants and could be an effective classical biological control agent if released in Florida, especially if it is not limited by a specialist third trophic level.

Current and Future Insect Threats to Oaks of the Midwest, Great Lakes, and Northeastern United States and Canada

Increasing temperatures, prolonged drought, the increased severity and intensity of storms, and other effects of climate change are being felt globally, and long-lived forest tree species may struggle in their current ranges. Oaks (Quercus spp.) have evolved a range of adaptations to dry and hot conditions and are believed to be a “climate change winner” by increasing their suitable habitat. However, a mixture of life history traits and increasing susceptibility to herbivores and xylovores as well as secondary pathogen infections still put oaks at risk of decline. Oak species found in the Midwestern, Great Lakes, and Northeastern United States and Canada are important keystone species with high ecological and economical importance. They are also vulnerable to existing, new, and emerging threats that have the potential to cause mortality across entire stands quickly. Current examples of insect threats include the Lymantria dispar (spongy moth), Agrilus bilineatus (twolined chestnut borer), and Nitidulidae (sap beetles) as disease vectors. Examples of emerging insects of concern include Cynipidae (oak gall wasps) and Enaphalodes rufulus (red oak borer). This study describes these insects, explains their mechanisms of action and the effects on oaks, and explores mitigation strategies for each.

Reticulodermis lithogalla gen. nov. and sp. nov. of oak gall wasp from Mexico (Hymenoptera, Cynipidae)

A new genus of oak gall wasp, Reticulodermis Pujade-Villar, Cuesta-Porta & Melika gen. nov. and a new species R. lithogalla García-Martiñón & Pujade-Villar sp. nov. are described from Mexico. Reticulodermis is known only from the asexual generation that induces galls on leaves of Quercus crassipes Humb. & Bonpl. (section Lobatae). We provide the diagnosis, distribution and biological data on the new species. An identification key to the genera of oak gall wasps inducing galls on the section Lobatae is given.

Successful gall induction on wild roses by gall wasps under lab conditions

Abstract Plant galls are unique outgrowths caused by various organisms, including insects, serving as nourishment for the inducer's larvae. Despite the taxonomists and ecologists attempts to elucidate the mechanisms behind plant gall formation, its understanding is still incomplete. Modern genetic techniques allow in‐depth analysis of the molecular processes, but variations across species entangle the analysis. Establishing laboratory‐friendly plant–gall inducer communities is crucial, yet past attempts have faced challenges. Our study partly aimed to create a laboratory community involving wild roses (Rosa sp.) and rose gall wasps belonging to the genus Diplolepis as gall‐inducing insects. Controlled indoor conditions were optimized for plant growth. Wild roses were transplanted, then exposed to gall inducers, and monitored. Successfully initialized gall growth was measured and analysed, revealing insights into the impact of plant vigour on gall size as a secondary aim. Our study successfully established a novel laboratory community for further research on gall formation mechanisms.

Ecological Impact of American Chestnut Hybrid Restoration on Invertebrate Communities Above- and Belowground

The cross-hybridization of American chestnut (Castanea dentata (Marsh.) Borkh.) with Chinese chestnut (Castanea mollissima Bl.) is a promising strategy for restoring a blight-resistant strain of this keystone species to the Appalachian mountains. To assess the ecological impacts of hybridization on invertebrate communities, we conducted a study across chestnut plots with varying degrees of hybridization (75%, 94%, or 100% American chestnut). Our findings indicate American chestnut hybridization impacted invertebrate communities above- and belowground. Aboveground insect community composition, insect herbivory, gall infestation, and belowground invertebrate diversity were all altered. While some of these differences could be explained by different growth habits or environmental differences, stark differences in Asian chestnut gall wasp infestation (Dryocosmus kuriphilus Yasumatsu.) suggest a genetic component. These results suggest that chestnut hybridization, and particularly expanded restoration efforts using chestnut hybrids, could impact invertebrate communities above- and belowground in addition to pest dynamics. Understanding these effects is crucial for successful chestnut restoration and ecosystem management.

Gall wasp susceptibility of chestnut cultivars in an organic South Carolina orchard

Gall wasp susceptibility of chestnut cultivars in an organic South Carolina orchard

Anatomical Changes during Chestnut (Castanea mollissima BL.) Gall Development Stages Induced by the Gall Wasp Dryocosmus kuriphilus (Hymenoptera: Cynipidae).

This study delved into the larval development and the morphological and anatomical transformations that occur in the galls of chestnut trees (Castanea mollissima BL.) and are induced by the chestnut gall wasp Dryocosmus kuriphilus Yasumatsu (GWDK) across various stages: initial, growth, differentiation, maturity, and lignification. Chestnut galls in the five development stages were collected. Gall structural characteristics were observed with an anatomical stereomicroscope, and anatomical changes in galls were analyzed with staining and scanning electron microscope techniques. The chestnut gall wasp laid its eggs on young leaves and buds. Chestnut gall wasp parasitism caused plant tissues to form a gall chamber, with parenchyma, protective, and epidermal layers. The development of the gall structure caused by the infestation of the GWDK gall led to the weakening of the reactive oxygen species (ROS) elimination ability of the host. The accumulation of ROS led to cell wall peroxidation, resulting in structural damage and diminished host resistance, and the parenchyma layer exhibited significant nutrient supply and thickening. The thickness of the protective and epidermal layers varied notably across different growth stages. The oviposition of the chestnut gall wasp induced modifications in the original plant tissues, with gall formation being most favorable in young tissues, correlating with the maturity level of the host plant tissues. Variances in the internal structures of the galls primarily stemmed from nutrient supplementation, while those in the external structure were attributed to defensive characteristics. This research contributes a foundational understanding of gall development induced by the chestnut gall wasp in Chinese chestnut, offering valuable insights into the intricate interplay between insect infestation and plant physiology.

Description of a new species of Andricus Hartig, 1840 (Hymenoptera: Cynipidae: Cynipini) from China

A new species of gall wasp, Andricus wugangensis Zeng, Liu, & Zhu sp. nov. is described and illustrated herein from Hunan Province, China. The new species is most similar to A. wuhanensis Ide, Abe, Su & Zhu and A. xishuangbanaensis Melika & Tang in morphology but can be easily distinguished by having 1) a large V-shaped carina on the lower face and 2) a broad transverse depression spanning the region between the inner margin of the eyes on the upper face. The results of a phylogenetic analysis and pairwise genetic distance comparison, based on COI sequences, were consistent with the conclusion of the comparative morphological assessment of the similar species: A. wuganensis, A. wuhanensis and A. xishuangbanaensis, although the morphological differences are more obvious than the small genetic distance of the COI sequences, which is 4.3% and 3% between the new species and A. wuhanensis and A. xishuangbanaensis, respectively. Additionally, a taxonomic key to the known species of Andricus from China is provided.

New species of gall wasps (Hymenoptera: Cynipidae: Aulacideini and Phanacidini) inducing galls on plants of the genera Sonchus and Crepis (Asteraceae) in Romania (Dobrogea Province) and notes on their parasitoids

Two new species of herb gall wasps (Hym., Cynipidae) developing on plants in the genera Sonchus L. and Crepis L. (Asteraceae) are described from Southeastern Romania (Dobrogea Province): Aulacidea andriescui sp. n. gall inducer on Sonchus palustris L. and Phanacis dobrogicus sp. n. gall maker on Crepis foetida subsp. rhoeadifolia (M. Bieb.) Čelak. In addition to the diagnosis, identification, morphological description, life-cycle, geographical distribution, photos of gall and host plant, and SEM images, data on the associated fauna obtained from the galls of the two new species are also presented.

Modelling suggests Wolbachia-induced cytoplasmic incompatibility in oak gall wasps with cyclical parthenogenesis.

Oak gall wasps typically exhibit a life cycle with one sexual and one asexual generation each year. These wasps can carry various endosymbionts, one of which is the maternally inherited bacterium Wolbachia that can induce several reproductive manipulations on its host. Cytoplasmic incompatibility (CI) has been described as the most prominent of these manipulations. CI leads to embryonic mortality in the hosts' offspring when infected males mate with either uninfected females or with females that harbour different Wolbachia strains. It has been hypothesized that Wolbachia can induce CI in oak gall wasps. To address this hypothesis, we derived a mathematical model to investigate the spread of a bacterial infection in naive populations and to determine the plausibility of CI occurrence. To validate our model, we used published data from Wolbachia-infected Belonocnema kinseyi populations in two approaches. Our first approach uses measurements of infection frequencies and maternal transmission in the sexual generation. For the second approach, we extended the model to compare predictions to estimates of mtDNA-haplotypes, which, like Wolbachia, are maternally inherited, and can therefore be associated with the infection. Both approaches indicate that CI is present in these populations. Our model can be generalized to investigate the occurrence of CI not only for oak gall wasps but also for other species.

Comparative transcriptome reprogramming in oak galls containing asexual or sexual generations of gall wasps.

Oak gall wasps have evolved strategies to manipulate the developmental pathways of their host to induce gall formation. This provides shelter and nutrients for the developing larva. Galls are entirely host tissue; however, the initiation, development, and physical appearance are controlled by the inducer. The underlying molecular mechanisms of gall formation, by which one or a small number of cells are reprogrammed and commit to a novel developmental path, are poorly understood. In this study, we sought a deeper insight into the molecular underpinnings of this process. Oak gall wasps have two generations each year, one sexual, and one asexual. Galls formed by these two generations exhibit a markedly different appearance. We sequenced transcriptomes of both the asexual and sexual generations of Neuroterus quercusbaccarum and Neuroterus numismalis. We then deployed Nanopore sequencing to generate long-read sequences to test the hypothesis that gall wasps introduce DNA insertions to determine gall development. We detected potential genome rearrangements but did not uncover any non-host DNA insertions. Transcriptome analysis revealed that transcriptomes of the sexual generations of distinct species of wasp are more similar than inter-generational comparisons from the same species of wasp. Our results highlight the intricate interplay between the host leaves and gall development, suggesting that season and requirements of the gall structure play a larger role than species in controlling gall development and structure.

Gall wasp (Cynipoidea: Cynipidae and Diplolepididae) fauna of the Eastern Black Sea Region (Türkiye)

In the period between October 2017 and September 2019, field studies were conducted with the aim of elucidating the gall wasp (Hymenoptera: Cynipidae and Diplolepididae) fauna of the Eastern Black Sea Region (Northeastern Türkiye). Gall samples were collected from 695 different localities within the research area, comprising a total of seven provinces (Artvin, Bayburt, Giresun, Gümüşhane, Ordu, Rize and Trabzon). As a result of these investigations, a total of 90 species belonging to 18 genera were recorded. Three of these species (Synergus consobrinus Giraud in Houard, 1911; S. reinhardi Mayr, 1872; S. ruficornis Hartig, 1840) represent new records for the inquiline (Synergini) fauna of Türkiye. The host plants, distributions, and distribution maps for all of the species recorded from the Eastern Black Sea Region are provided.