Oak Gall Wasp Species Research Articles

Diversity of gall wasps (Hymenoptera: Cynipidae) associated with oak trees (Fagaceae: Quercus) in a fragmented landscape in Mexico

Habitat fragmentation reduces the available habitat area and increases both the distance between fragments and the amount of fragment edges. Therefore, there are more probabilities of plant population size reduction and species extinction. In the same way, biotic and abiotic changes associated with forest fragmentation can dramatically alter plant growth and phenological patterns. We conducted a 3-year study to analyze effects of habitat fragmentation and seasonal variation on host plant quality (quantity of leaves, diameter at breast height, tree height), gall abundance and species richness in a temperate oak forest. Our results show that host plant quality was significantly higher in isolated oaks and small fragments, increasing the abundance and species richness of oak gall wasp species in most fragmented habitats. Oak canopy cover is altered by forest fragmentation, there being higher production of leaves on trees that are more exposed to fragmentation, and can provide important resources for maintaining gall wasp species diversity in a fragmented landscape. We found higher gall wasp richness and abundance in autumn than in the spring, which matches with the higher quantity of leaves in this season.

Invasive chestnut gall wasp Dryocosmus kuriphilus (Hymenoptera: Cynipidae), its native parasitoid community and association with oak gall wasps in Slovenia

The Asian chestnut gall wasp (ACGW), Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae), is a global pest of chestnut trees. This pest was first recorded in Slovenia in 2005. Despite strict phytosanitary measures it was present throughout the country in native chestnut stands by 2013. We provide here the first overview of the parasitoids of ACGW in Slovenia recorded over a 4-year period and the direct interactions between parasitoid communities attacking hosts on chestnut and oaks at the same sites. A total of 27 species of native parasitoids that normally parasitize oak cynipids emerged from ACGW galls. The most abundant species were Torymus flavipes and Eupelmus urozonus. Seven species appear to be geographically well distributed in Slovenia. Twelve species of oak gall wasp were parasitized by 19 species of parasitoids. All native parasitoids have broad host ranges, so a large parasitoid diversity within this community can be expected. This is a novel study comparing the parasitoid communities associated with chestnut and oak galls.

Modeling the potential distribution and conservation status of three species of oak gall wasps (Hymenoptera: Cynipidae) in the Iberian range

Cynipids (Hymenoptera: Cynipidae) induce a wide variety of complex galls on plants of different botanical families, particularly on Quercus species. Cynipid galls are well known to host large communities of insects, providing fundamental ecological niches for different animal taxa, which are organized in structured and relatively isolated communities at the microhabitat level. Gall communities of Quercus woodlands could be a conservation concern considering some risks, which affect several species of the Parasitica group of Hymenoptera, within which gall wasps and their parasitoids and inquilines are included. These risks concerning Parasitica species are mainly due to three causes: their high trophic level, high host specialization and the lack of knowledge of their biology. In this paper, a preliminary approach to this issue is presented for the Iberian–Balearic range. We model and study the ecological niche of three cynipid gall species that induce galls on Quercus species (Andricus quercustozae, Biorhiza pallida and Plagiotrochus quercusilicis). The cynipid gall species were selected for their different sets of host species and life cycle. The Ecological Niche Factor Analysis and two niche models built for each species (MAXENT and Mahalanobis Distances) support the interpretation that the bioclimatic variables considered have effects on cynipids through their respective sets of host plants. In addition, the results regarding A. quercustozae are consistent with the hypothetical existence of cryptic sexual generation (exposed in other works) parasitizing cork oak (Quercus suber), which could have another key role in its conservation.

First evidence of cynipids from the Oceanian Region: the description of Lithonecrus papuanus a new genus and species of cynipid inquiline from Papua New Guinea (Hymenoptera: Cynipidae, Synergini).

Lithonecrus papuanus Nieves-Aldrey & Butterill, a new genus and species of inquiline oak gall wasps (Hymenoptera: Cynipidae: Synergini), is described from material reared from galls on Lithocarpus celebicus (Miq.) Rehd., collected in Papua New Guinea. The new genus and species is the first record of a cynipid from Papua New Guinea and the whole Oceanian biogeographic region, and represents the easternmost oriental record of a cynipid wasp (Hymenoptera: Cynipidae). The new genus is similar to Saphonecrus Dalla Torre & Kieffer, and to the recently described Lithosaphonecrus Tang, Melika & Bozsó, but differs from these genera in several important diagnostic characters. Taxonomic affinities and differences with related genera and species and biogeographical implications are discussed.

TORYMUS SINENSIS: BIOLOGY, HOST RANGE AND HYBRIDIZATION

Torymus sinensis is a solitary ectophagous parasitoid of the chestnut gallwasp, Dryocosmus kuriphilus. It originates, like its host, from China. Following the accidental introduction and rapid range expansion of the pest in Japan (in the 40s),USA (70s) and Italy (2000s), T. sinensis was introduced into these countries as a biological control agent. While its effectiveness in controlling the pest was confirmed in Japan, and recently in Italy, some aspects of its biology are still unknown or at most scarcely investigated. Preliminary tests were performed in order to investigate some important aspect of its biology. The rearing of D. kuriphilus galls over 2 years revealed a second emergence period of T. sinensis adults. About 3% of a cohort showed such prolonged diapause. Extended diapause is an extremely rare strategy among oak gall parasitoids, most of which are polyphagous on the oak gall community. T. sinensis, in contrast, is specific to apparently only one host species, the gallinducer D. kuriphilus, and if the availability of D. kuriphilus galls were to be unpredictable, extended diapausing might be expected to be selected. Extended diapause also makes T. sinensis a better biocontrol agent because local populations are more likely to survive temporary extinction of the host population. Tests on the host range of T. sinensis were performed using 7 species of oak gallwasps which occur at similar times in the field to D. kuriphilus: Andricus crispator, A. curvator, A. cydoniae, A. grossulariae, A. multiplicatus, Biorhiza pallida and Dryocosmus cerriphilus. Few and brief ovipositor prickings were observed on A. cydoniae, B. pallida and D. cerriphilus but no eggs were laid. These data confirm the host gall specificity of T. sinensis in Europe. In order to assess the probability of hybridization of the introduced parasitoid with native European Torymus species, mate recognition was tested using 4 native species: T. flavipes, T. auratus, T. affinis and T. geranii. The natural mating behaviour of T. sinensis involves a “dance” with the male approaching the female and shaking its wings and swaying the body. No mate recognition was recorded using the native species. Although mating behaviour like the one shown by T. sinensis could make cross breeding less likely, it is important to note that the native species tested are difficult to mate under controlled conditions in any event, and other species, such as T. notatus and T. cyaneus (more closely related to T. sinensis) should also be tested.

First Record ofLoxaulusMayr from Mexico, with Descriptions of Two New Species (Hymenoptera: Cynipidae, Cynipini)

Abstract. Two new species of oak gallwasp, Loxaulus hyalinus Pujade-Villar & Melika n. sp. and L. laeta Pujade-Villar n. sp. are described from Mexico. They represent the first records of this genus in Mexico. Both species are known from asexual generations and induce galls on endemic Mexican Quercus: Q. dysophylla Benth. and Q. laeta, respectively. Data on the diagnosis, distribution, and biology of the new species are given.

Andricus breviramuliPujade-Villar n. sp. (Hymenoptera: Cynipidae: Cynipini): New Pest of Oaks in Mexico

A new species of oak gall wasp, Andricus breviramuli Pujade-Villar n. sp., is described from Mexico. The species is known only from asexual females. Data on the diagnosis, distribution, and biology of the new species are given. The wasp induces galls on twigs and young shoots of Quercus laeta Liebm. This gall wasp seems to be a serious pest of Q. laeta in Santa Fe (Delegación Cuajimalpa, DF), México City.

Four new species of Andricus Hartig oak gallwasp from Turkey <br />(Hymenoptera: Cynipidae, Cynipini)

Four new species of oak gallwasps, Andricus ahmeti, A. anatolicus, A. bakrachus and A. turcicus (Hymenoptera: Cynipidae: Cynipini) are described from Turkey. All four species are known only from asexual females and induce galls on twigs and young shoots on Q. infectoria, Q. macranthera and Q. petraea. Data on the diagnosis, distribution and biology of the four new species are given. Andricus stonei and Aphelonyx kordestanica are listed for the first time for the Turkish oak gallwasp fauna.

Barucynips panamensis, a new genus and species of oak gallwasps (Hymenoptera, Cynipidae, Cynipini) from Panama, and description of one new species of Coffeikokkos

Barucynips panamensis Medianero & Nieves-Aldrey, a new genus and species of oak gallwasps (Hymenoptera: Cynipidae: Cynipini), is described from adults reared from galls on Quercus bumelioides in Panama. The new genus is taxonomically close to the recently described Coffeikokkos from Costa Rica, but differs from it and all of the described genera of Cynipini, by the shape and setation of the projecting part of the ventral spine of the hypopygium and by the sculpture of the propodeum. A new species of Coffeikokkos is also described from the same area, the Volcán Barú in Panama. Diagnostic characters, gall description, distribution, and biological data of the new genus and the two new species are given. The new genus is the first genus of oak gallwasps of the tribe Cynipini described in Panama.

A new Andricus Hartig oak gallwasp species from China (Hymenoptera: Cynipidae: Cynipini)

A new species of oak gallwasp, Andricus xishuangbannaus is described from China. The species induces leaf galls on Quercus griffithii (Fagaceae). Diagnosis, distribution, and biology of the new species are included.

A new Latuspina Monzen oak gallwasp species from Taiwan (Hymenoptera: Cynipidae: Cynipini)

A new species of oak gallwasp, Latuspina manmiaoyangae sp. nov., is described in Taiwan. The species induces leaf galls on Quercus variabilis (Fagaceae). Data on the diagnosis, distribution, and biology of the new species are given. This is the second known Latuspina species.

New Amphibolips gallwasp species from Mexico (Hymenoptera: Cynipidae)

Two new species of oak gallwasp, Amphibolips zacatecaensis Melika & Pujade-Villar and A. hidalgoensis Pujade-Villar & Melika, are described from Mexico, known to induce galls on Quercus eduardi, Q. crassipes, Q. candicans and Q. crassifolia (section Lobatae, red oaks). Only females are known. Data on the diagnosis, distribution and biology of the new species are given.

Four New Species of Dryocosmus gallwasps from Taiwan (Hymenoptera: Cynipidae: Cynipini)

Four new species of oak gallwasps of the genus Dryocosmus: D. pentagonalis, D. triangularis, D. carlesiae, and D. testisimilis are described from Taiwan. They induce galls on one species of Castanopsis and one species of Lithocarpus (Fagaceae). Data on the diagnosis, distribution, and biology of the four new species is given. A key for Dryocosmus species identification of Taiwan is provided. Final comments discuss the polyphyletic nature of the Dryocosmus genus, emphasizing the urgent need for its revision.

New species of oak gallwasps from Taiwan (Hymenoptera: Cynipidae: Cynipini)

Three new species of oak gallwasps from Taiwan are described: Andricus songshui and Andricus pseudocurvator, both known to induce integral leaf galls on Quercus serrata, and Plagiotrochus glaucus which induces stem swelling-like galls on Quercus glauca. Galls and adults of new species are described; data on the diagnosis, distribution and biology of the new species and a key to the Taiwanese Andricus species are also given.

A New Inquiline Species ofSaphonecrus(Hymenoptera: Cynipidae: Synergini) Associated with Cecidomyiid Galls on Oak Trees in Japan

AbstractA new inquiline oak gall wasp species, Saphonecrus yukawai Wachi, Ide & Abe, sp. nov. (Hymenoptera: Cynipidae: Synergini), is described from Japan. Although most inquiline oak gall wasps are associated with cynipid galls on Quercus trees, the adult wasps of S. yukawai emerged from galls induced by the gall midge Ametrodiplosis acutissima (Monzen) (Diptera: Cecidomyiidae) on Quercus (sect. Cerris) acutissima Carruthers. Host shift from cynipid galls to cecidomyiid galls in inquiline oak gall wasps is discussed.

Discovery of a New Plagiotrochus Species (Hymenoptera: Cynipidae) Inducing Galls on the Evergreen Oak in Japan

Abstract Plagiotrochus masudai Ide, Wachi & Abe sp. nov. (Hymenoptera: Cynipidae), a gall inducer on Quercus (Cyclohalanopsis) glauca Thunberg in Japan, is described. This is the first description of an oak gall wasp species (tribe Cynipini) inducing galls on Cyclohalanopsis. The unique life cycle of P. masudai takes 3 yr to complete. The adult wasps of the sexual generation emerge from bud galls on Q. glauca in spring of the first year, and those of the asexual generation emerge from twig galls in spring of the third year.

Agastoroxenia panamensis, a New Genus and Species of Inquiline Oak Gall Wasps (Hymenoptera: Cynipidae: Synergini) of the Neotropics

Abstract Agastoroxenia panamensis Nieves-Aldrey & Medianero, a new genus and species of inquiline oak gall wasps (Hymenoptera: Cynipidae: Synergini), is described from material reared from unidentified Andricus galls (Cynipini) on Quercus lancifolia Schltdl. & Cham. collected in Panama. The new genus is the first genus of inquiline oak gall wasps described from the Neotropics and the first species of this group recorded from Panama. The new genus is related to Saphonecrus and Synergus but differs from these genera mainly by the unique conformation of the male and female antenna.

First record of an Andricus oak gallwasp from the Oriental Region: a new species from Taiwan (Hymenoptera: Cynipidae: Cynipini)

A new species of oak gallwasp, Andricus formosanus is described from Taiwan which induces integral leaf galls on Quercus dentata (Section Quercus sensu stricto). The gall and adults of the new species most closely resembles Andricus moriokae Monzen, known from Japan. Data on the diagnosis, distribution and biology of the new species is given.

Evidence for widespread cryptic sexual generations in apparently purely asexual Andricus gallwasps

Oak gallwasps (Hymenoptera, Cynipidae, Cynipini) are one of seven major animal taxa that commonly reproduce by cyclical parthenogenesis (CP). A major question in research on CP taxa is the frequency with which lineages lose their sexual generations, and diversify as purely asexual radiations. Most oak gallwasp species are only known from an asexual generation, and secondary loss of sex has been conclusively demonstrated in several species, particularly members of the holarctic genus Andricus. This raises the possibility of widespread secondary loss of sex in the Cynipini, and of diversification within purely parthenogenetic lineages. We use two approaches based on analyses of allele frequency data to test for cryptic sexual generations in eight apparently asexual European species distributed through a major western palaearctic lineage of the gallwasp genus Andricus. All species showing adequate levels of polymorphism (7/8) showed signatures of sex compatible with cyclical parthenogenesis. We also use DNA sequence data to test the hypothesis that ignorance of these sexual generations (despite extensive study on this group) results from failure to discriminate among known but morphologically indistinguishable sexual generations. This hypothesis is supported: 35 sequences attributed by leading cynipid taxonomists to a single sexual adult morphospecies, Andricus burgundus, were found to represent the sexual generations of at least six Andricus species. We confirm cryptic sexual generations in a total of 11 Andricus species, suggesting that secondary loss of sex is rare in Andricus.

Lifecycle closure, lineage sorting, and hybridization revealed in a phylogenetic analysis of European oak gallwasps (Hymenoptera: Cynipidae: Cynipini) using mitochondrial sequence data

Oak gallwasps are cyclically parthenogenetic insects that induce a wide diversity of highly complex species- and generation-specific galls on oaks and other Fagaceae. Phylogenetic relationships within oak gallwasps remain to be established, while sexual and parthenogenetic generations of many species remain unpaired. Previous work on oak gallwasps has revealed substantial intra-specific variation, particularly between regions known to represent discrete Pleistocene glacial refuges. Here we use statistical phylogenetic inference methods on sequence data for a fragment of the mitochondrial cytochrome b gene to reconstruct the relationships among 62 oak gallwasp species. For 16 of these we also include 23 additional cytochrome b haplotype sequences from different Pleistocene refuge areas to test the effect of intra-specific variation on inter-specific phylogeny reconstruction. The reconstructed phylogenies show good intra-generic resolution and identify several conserved clades, but fail to reconstruct either very recent or very ancient divergences. Nine of the 16 species represented by multiple haplotypes are not monophyletic. The apparent discordance between the recovered gene tree and the current taxonomic classification can be explained through: (a) collapsing of some species currently known only from either a sexual or a parthenogenetic generation into a single cyclically parthenogenetic entity; (b) sorting of ancestral polymorphism in diverging lineages, and (c) horizontal transfer of haplotypes, perhaps due to hybridization within glacial refuges. Our conclusions emphasise the need for careful intra-specific sampling when reconstructing phylogenies for radiations of closely related species and imply that for certain taxonomic groups full phylogenetic resolution (using molecular markers) may not be attainable.