Alteration of free amino acid concentrations in insect galls induced by Andricus mukaigawae (Hymenoptera; Cynipidae)

1. Insect galls are abnormal plant growths that develop in response to a stimulus provided by a galling insect. The nutrition hypothesis suggests that the concentrations of nutritive compounds in galls are changed to provide optimum nutrition for the larvae and adults of galling insects. 2. To test the nutrition hypothesis, we determined the concentrations of 20 free amino acids in galls and in galled and ungalled twigs of Quercus fabri during the larval and adult stages of Andricus mukaigawae using high-performance liquid chromatography with ultraviolet–visible detection. 3. At the larval stage, the concentrations of 12 out of 20 amino acids in A. mukaigawae galls were significantly higher than those in galled and ungalled twigs. Asparagine and tryptophan were the most abundant nonessential and essential amino acids, respectively, in A. mukaigawae galls. 4. At the adult stage, the concentrations of most amino acids, except proline, were significantly lower in A. mukaigawae galls than in galled and ungalled twigs. The A. mukaigawae adults may not manipulate amino acid levels because the adults do not feed on galls. The decrease of amino acid levels in adult galls may be viewed as a depletion. 5. The composition of free amino acids in A. mukaigawae galls was significantly different from the composition in galled and ungalled twigs in both the larval and adult stages. 6. Our results may support the nutrition hypothesis. We suggest that a high concentration of proline in A. mukaigawae galls may protect larvae and adults from plant defense responses.     

The advantage of attending ants and gall aggregation for the gall wasp Andricus symbioticus (Hymenoptera: Cynipidae)

Summary Gall clusters of Andricus symbioticus secrete a sweet and sticky food attractive to ants. An ant exclusion experiment demonstrated the selective advantage of attending ants and gall aggregation for A. symbioticus. This gall wasp interacts with the gall-attending ants only through the host plant. Evolution of this symbiotic relationship seems to be associated with gall aggregation.Contribution from Laboratory of Entomology Kyoto Prefectural University, No. 249     

Differential rates of invasion in three related alien oak gall wasps (Cynipidae: Hymenoptera)

Abstract. Three related species of oak gall wasps, Andricus corruptrix (Schlechtendal), A. kollari (Hartig) and A. lignicola (Hartig) have entered Britain since the introduction of Turkey oak, Quercus cerris L. in 1735. Their lifecycles involve alternating generations between an agamic generation on the native oak species (Q. petraea, Q. robur and their hybrid Q. x. rosacea), and a smaller, sexual generation on the alien Q. cerris. In examining the distributions of these insects and Q. cerris, we hypothesized that: (1) the invasion will spread more rapidly in places where both host trees are equally abundant than through regions where one of the tree species is substantially less common than the other; (2) interspecific competition between these bud‐galling species will lead to a negative correlation between their abundances at a particular site; (3) differential recruitment of natural enemies from the native hymenopteran fauna will slow the rate of spread in a species‐specific manner. A. kollari arrived nearly 200 years ago and is now found throughout the British Isles, wherever Turkey oak is grown. A. lignicola and A. corruptrix have been here for 30 years, after establishing in S.E. England. A. lignicola is in its final rapid stages of range expansion across England, southern Scotland and N.E. Scotland. A. corruptrix is just beginning to spread through Central and S.W. England. It has occupied proportionally fewer sites behind its invasion front than have the other two species, but is no less abundant at these sites. Nevertheless, distance leaps of up to 50 km were identified in A. lignicola in N.E. Scotland, and the possibility of long‐distance transport of infected trees through the horticulture and forestry trades remains. The co‐occurrence of mature individuals of both host Quercus species does appear to have increased their rates of colonization in A. lignicola and A. corruptrix. There is no evidence, however, to suggest that interspecific competition between the three alien gall formers is an important factor in determining their distributions and abundance within their invaded ranges. All three species have recruited parasitoids and inquilines rapidly from the native fauna; attack rates were highly variable, but showed no evidence of density dependence across sites.     

湖南三地区麦氏安瘿蜂体内Wolbachia 的感染及其wsp基因序列分析

为检测麦氏安瘿蜂Andricus mairei Kieffer有无Wolbachia感染, 本研究对其岳阳、 长沙和邵阳3种群雌、 雄成虫体内Wolbachia的wsp基因进行了PCR检测, 进而对获得的基因片段进行了序列分析。结果显示, 麦氏安瘿蜂岳阳、 长沙及邵阳种群雌、 雄成虫均有Wolbachia感染, 除邵阳种群雌成虫的感染率为80%之外, 其他均为100%。3个种群Wolbachia的wsp基因序列长度皆为561 bp, 且序列完全一致。麦氏安瘿蜂Wolbachia的wsp基因序列与已知瘿蜂族(Cynipini) Neuroterus macropterus、 Biorhiza pallida及Andricus solitarius （strain 1）以及Synergini族Synergus crassicornis感染的Wolbachia的一致性达95%。除Synergini族Ceroptres cerri感染的Wolbachia属于B群（B group）之外, 瘿蜂感染的Wolbachia均属于A群（A group）。在NJ系统树中, 麦氏安瘿蜂与瘿蜂族Neuroterus macropterus、 Biorhiza pallida和Andricus solitarius （strain 1）及Synergini族Synergus crassicornis感染的Wolbachia聚合在同一分支。此外, 麦氏安瘿蜂岳阳、 长沙和邵阳种群均获得了雌、 雄成虫, 其雌性率分别为15.3%, 12.1%和19.8%, 表现出明显的雄性比偏高。结果提示与瘿蜂族的其他已报道的种类一样, Wolbachia与麦氏安瘿蜂的共生并不诱导其营产雌孤雌生殖。     

New species of gallwasps inducing in Quercus fabri and its inquiline(Hymenoptera: Cynipidae) in China

New species of gallwasps, Andricus flavus sp. nov., and its inquiline related to its gall, Saphonecrus fabris sp. nov. are described. Both species are included and illustrated their distribution and biology here. The type materials are deposited in the Parasitic Hymenoptera Collection, Zhejiang Agricultural and Forest University, Lin'an, China, and University of Barcelona Barcelona, Spain.     

A phylogenetic analysis of higher-level gall wasp relationships (Hymenoptera: Cynipidae)

We present the most comprehensive analysis of higher-level relationships in gall wasps conducted thus far. The analysis was based on detailed study of the skeletal morphology of adults, resulting in 164 phylogenetically informative characters, complemented with a few biological characters. Thirty-seven cynipid species from thirty-one genera, including four genera of the apparently monophyletic Cynipini and almost all of the genera in the other tribes, were examined. The outgroup included exemplar species from three successively more distant cynipoid families: Figitidae (the sister group of the Cynipidae), Liopteridae and Ibaliidae. There was considerable homoplasy in the data, but many groupings in the shortest tree were nonetheless well supported, as indicated by bootstrap proportions and decay indices. Partitioning of the data suggested that the high level of homoplasy is characteristic of the Cynipidae and not the result of the amount of available phylogenetically conservative characters being exhausted. The analysis supported the monophyly of the Cynipini (oak gall wasps) which, together with the Rhoditini (the rose gall wasps), Eschatocerini and Pediaspidini formed a larger monophyletic group of gall inducers restricted to woody representatives of the eudicot subclass Rosidae. The inquilines (Synergini) were indicated to be monophyletic, whereas the Aylacini, primarily herb gall inducers, appeared as a paraphyletic assemblage of basal cynipid groups. The shortest tree suggests that the Cynipidae can be divided into three major lineages: one including the inquilines, the Aylacini genera associated with Rosaceae, and Liposthenes ; one consisting entirely of Aylacini genera, among them Aulacidea , Isocolus and Neaylax ; and one comprising the woody rosid gallers (the oak and rose gall wasps and allies), the Phanacis-Timaspis complex and the Aylacini genera associated with Papaveraceae.     

Detection of two different mitochondrial genomes in a gall wasp species,Andricus mairei (Hymenoptera: Cynipoidea: Cynipidae)

Mitochondrial genomes (mitogenomes) have been used widely in comparative and evolutionary genomics, molecular evolution, phylogenetics, and population genetics, but very limited information is available for the family Cynipidae. In this report, we described the mitogenome of Andricus mairei. The mitogenome of A. mairei was 16,514 bp in length and contained a typical set of 37 genes. Two control regions (CRs) were detected, one being a partial reverse repeat of the other. In a comparison with the putative ancestral mitogenome, gene rearrangements were found in transfer RNA (tRNA) genes, protein-coding genes and ribosomal RNA (rRNA) genes. Consistent with other Cynipidae species, the gene rearrangement of A. mairei had four obvious characteristics: trnE and trnF had inverted and swapped positions; rrnL and rrnS genes had moved into the cob–nad1 junction; a novel tRNA gene cluster trnL1–trnI–trnL2–trnW–trnM–trnQ had been formed between nad1 and nad2; and trnV had inverted and moved to the nad2–cox1 gene junction. Furthermore, A. mairei had two types of mitochondrial circular DNA molecules. Type II differed from type I in an inverted rearrangement of a large fragment of 3349 nucleotides, including two CRs and two rRNA genes.     

Population ecology and spatial synchrony in the abundance of leaf gall wasps within and among populations of valley oak (Quercus lobata)

What factors drive population variability through space and time? Here we assess patterns of abundance of seven species of gall wasps in three genera occurring on the leaves of valley oaks (Quercus lobata) at 10 sites throughout this species' statewide range in California, from 2000 to 2006. Our primary goals were to understand the factors driving variability in gall abundance and to assess the extent of spatial synchrony in gall wasp communities at both large and small geographic scales. On the large, statewide scale, there was significant site-to-site variation in gall abundance, driven in all cases primarily by differences in mean maximum seasonal temperatures, and lesser year-to-year variation. In contrast, on the small, local scale, differences were more pronounced from year to year than from tree to tree, and were to some extent correlated with differences in acorn production, suggesting an interaction with the reproductive effort of hosts. Significant spatial synchrony was detected, particularly at the statewide scale, but in no case did synchrony decline significantly with distance, despite sites being up to 741 km apart. Variation in spatial synchrony was correlated with a number of exogenous factors, including seasonal weather conditions, the acorn crop at the statewide scale and soil phosphorus availability at the local scale; however, most variation in spatial synchrony in our analyses remained unexplained.     

Population dynamics of the chestnut gall wasp,Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae)

Summary During the course of a 10-year investigation on the population dynamics of Dryocosmus kuriphilus, a rapid decrease in the number of individuals was noticed in the adult stage. To detect the role of predation by spiders in causing this high adult mortality, spiders collected from the survey station were tested for their reaction to Drycosmus antiserum. About 2050% of the spiders collected during the emergence period of D. kuriphilus reacted positively, showing that the species of Thomisidae, Argiopidae, Agelenidae and Salticidae were the important predators. The predation ratio for the total adult wasp population was estimated at 8.1% in 1968, 20.2% in 1969 and much higher in 1970, increasing with decreasing population density of the wasps. However, the predation by spiders could not account for all of the adult mortality of D. kuriphilus.     

Invaders on the move: parasitism in the sexual galls of four alien gall wasps in Britain (Hymenoptera: Cynipidae)

Four alien, host-alternating cynipid gall wasps are established in the British Isles: Andricus kollari, A. lignicola, A. quercuscalicis and A. corruptrix. Their current distributions divide Britain into four zones; all four invaders are present in the south and south-east of Britain, whereas only A. kollari is present in the far north of Scotland. The rank order, according to how far north the distributions of the four invading cynipid species reach, is: A. corruptrix→ A. quercuscalicis→ A. lignicola→ A. kollari. The life cycles of all four cynipid species involve a sexual generation in spring on Quercus cerris, and an agamic generation in autumn on Q. robur. Here we studied the parasitoid attack by four pteromalid species on the sexual generations of the invaders. We collected and reared the galls of all four species at eight sites from the south to the north of the country (two sites per zone). The geographical locations of the sites reflect the invasion history and thus the residence time of the alien species in the four zones. At each site we measured the densities of all host galls on Q. cerris and of both obligatory host-tree species. We also took a series of measures, such as host-tree density and mean host-tree size, to further characterize the tree stands. These measures are referred to as local parameters. Host densities varied between sites and between years. In A. kollari, galling rates were highest in the middle of the country (zone 2) in 1994, whereas in 1995 they increased from the south to the north. In A. lignicola, galling rates in both years were lowest at the sites in zone 3 (closest to its distribution boundary). In A. quercuscalicis, galling rates were found to be lowest at the site most to the north-west in both years, again the one furthest away from the area where this species was first recorded. Mortality caused by parasitoid attack differed from less than 10% to as high as 70% and varied between host species, sites and years. In four out of six cases the historical/regional variables (north/south and east/west) correlated significantly with parasitoid attack rates that were characteristically lowest at sites close to the distribution boundaries. Of the local factors, we found parasitoid attack rates correlated negatively in one case with host density, whereas they correlated positively in four cases with the density of alternative hosts of the parasitoids. In one of the models the local density of Q. cerris trees correlated negatively with parasitoid attack on A. quercuscalicis. For all three host species the terms retained in the minimal adequate models obtained for 1994 and 1995 differed, which might indicate that these communities of native parasitoids and invading host have not yet settled in any definite structure.     

Population genetic structure and phylogeography of the oak gall wasp Andricus chodjaii (Hymenoptera: Cynipidae) in Turkey as inferred from mitochondrial and nuclear DNA sequences

Sequence data of mitochondrial cytochrome b gene and nuclear ITS2 region were used to assess genetic diversity, intraspecific phylogeography and population genetic structure of the oak gall wasp Andricus chodjaii from Turkey. We examined 293 individuals from 21 localities which generated 57 cyt b haplotypes and 8 ITS2 alleles. The average genetic diversity was 0.575 for cyt b and 0.202 ITS2, and the average nucleotide diversity 0.015 for cyt b gene and 0.001 for the ITS2 region. Phylogenetic analyses of cyt b haplotypes produced mostly similar topologies with geographically significant groupings. The ITS2 data provided less resolution without robust and apparent geographic structure. Population demographic analysis indicated that some eastern populations expanded, however, some others underwent either expansion or decline resulting in genetically structured populations. Molecular clock applied to the mtDNA data indicated that ingroup haplotypes diversified from the outgroup haplotypes around Early Pliocene. Further diversification events throughout Pleistocene resulted in major clade formations. It appears that geographic formations and glacial and interglacial cycles of Pleistocene were crucial for shaping the phylogeographic structure of A. chodjaii in Turkey.     

The protein content of tissues in cynipid galls (Hymenoptera: Cynipidae): Similarities between cynipid galls and seeds

Cynipid galls are examples of induced plant development, where the gall inducer is in control of cell differentiation and morphogenesis of a new plant organ. This study concentrates on the tissues of the larval chamber common to all cynipid galls. The protein content of the inner gall tissue was compared to that of non‐gall plant tissues. We investigated three oak and two rose galls and their respective host plants. Total protein signatures of inner gall tissues were different from those of non‐gall plant tissues, and among the five galls. N‐terminal sequences were obtained for two abundant proteins from the inner gall tissues of D. spinosa and A. quercuscalicis, which were common to all galls, at 62 and 43 kDa. Database queries suggest the 62 kDa protein to be homologous to a protein disulphide isomerase (PDI), and the 43 kDa protein to be homologous to NAD‐dependent formate dehydrogenase (FDH). A naturally biotinylated protein was detected at 33 kDa during Western analyses with streptavidin. Western analyses revealed the presence of the biotinylated protein and PDI in the inner gall tissues of all five galls, while FDH was only detected in A. quercuscalicis and A. fecundator. PDI was also common to all non‐gall tissues, while FDH was not detected in non‐gall tissues, and the biotinylated protein was only detected in seeds. The proteins identified in the inner gall tissue suggest that (a) inner gall tissues in some galls are under respiratory stress, and (b) cynipid gall formation might involve the ectopic expression of seed‐specific proteins.     

No host‐associated differentiation in the gall wasp Diplolepis rosae (Hymenoptera: Cynipidae) on three dog rose species

Differences in quality and quantity of secondary compounds, as well as in leaf traits of host plants, may influence the host choice of herbivores. Different host preferences could lead to host‐associated differentiation, the first step of sympatric speciation. In the present study, we investigated whether the rose gall wasp Diplolepis rosae L. (Hymenoptera: Cynipidae) shows genetic differentiation related to its host plants (Rosa canina L., Rosa corymbifera Borkh., and Rosa rubiginosa L.). These three host species radiated recently and subsequently expanded their range. Therefore, we expected a diversification within the closely‐associated phytophagous insects. The process of genetic differentiation should be intensified in D. rosae by its close relationship to the host plant, as well as by its parthenogenetic reproduction (infection rate by Wolbachia sp. of almost 100%). However, using 106 polymorphic amplified fragment length polymorphism markers, we found no genetic differentiation among the wasps from different host plants. The population structuring between geographical localities was also low, suggesting considerable gene flow between sites. In part, the low genetic differentiation between sites is explained by the wide distribution of host species and hybrids between host plants. Hybrids with intermediate traits may facilitate the gene flow between wasp populations exploiting different host species. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 369–377.     

The effect of leaf galls of Cynipidae on accumulation and biosynthesis of plant amines in oak trees

Polyamines (PAs) are involved in plant response to abiotic and biotic stresses, however, their role in biochemical insect-plant interactions is not clear. Therefore, we compared the involvement of polyamines and key enzymes of their biosynthesis in gall formation process. The present study had used galls on oak leaves caused by asexual generation (♀♀) of three Cynipidae species, namely Cynips quercusfolii L., Neuroterus numismalis (Fourc.) and N. quercusbaccarum L., as a model. The obtained results indicate that gall formation on oak leaves affected amine content, but intensity of the changes in their levels were strongly dependent on the insect species. Nevertheless the downward trend was dominant among those changes. Changes in the activity of lysine decarboxylase (LDC), tyrosine decarboxylase (TyDC) and ornithine decarboxylase (ODC) usually corresponded with the direction of changes in polyamine contents. Several cases of divergence between changes in amine levels and the rate of their biosynthesis may suggest the involvement of other regulation mechanisms such as: arginine decarboxylase (ADC) and S-adenosylmethionine decarboxylase (SAMDC) as well as amine oxidases involved in its catabolic pathways. Thus, the future studies on biochemical mechanism of regulation of PAs accumulation during galls formation should be focused on importance of these enzymes.     

A new species of Isocolus from Spain (Hymenoptera,Cynipidae) inducing galls in flower heads of Leuzea conifera (Asteraceae)

A new species of Isocolus Förster (Hymenoptera, Cynipidae “Aylacini”) is described from Spain: Isocolus leuzeae n. sp. The new species induces galls in flower heads of Leuzea conifera (Asteraceae) and represents the first known aylacin species associated with this plant. The species is closely related to Isocolus lichtensteini (Mayr) that induces galls on stems of Centaurea aspera. Biological data on its life cycle, larva and gall are provided.     

Ant mutualists alter the composition and attack rate of the parasitoid community for the gall wasp Disholcaspis eldoradensis (Cynipidae)

Abstract.  1. The strength or density dependence of pairwise species interactions can depend on the presence or absence of other species, especially potential mutualists.
2. The gall wasp Disholcaspis eldoradensis induces plant galls that secrete a sweet honeydew from their top surfaces while the wasp larvae are active. These galls are actively tended by Argentine ants, which collect the honeydew and drive off parasitoids attempting to attack the gall wasp.
3. When ants were excluded, the total rate of parasitism by seven species of parasitoids increased by 36%, and the rate of gall-wasp emergence decreased by 54%.
4. The total percentage parasitism was affected by gall density when ants were excluded but not when ants were unmanipulated, suggesting a change in parasitoid functional responses due to ant tending.
5. In addition, excluding ants significantly altered the proportions of different parasitoid species that emerged from galls; one parasitoid species increased from 1% to 34%, and another decreased from 46% to 19%.
6. The invasive Argentine ants studied are capable of maintaining the mutualism with the gall wasps that evolved in the presence of different ant species and also act as a selective filter for the local community of generalist parasitoids trying to attack this gall species.