Cynipidae Research Articles

Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae) in Minho (Northern Portugal): Bioecology, Native Parasitoid Communities and Biological Control with Torymus sinensis Kamijo (Hymenoptera: Torymidae)

The Asian chestnut gall wasp Dryocosmus kuriphilus Yasumatsu, native to China, was first detected in Europe in Italy in 2002. In Portugal it was declared in 2014, and it has since affected the Portuguese chestnut production. The introduction of its natural parasitoid Torymus sinensis Kamijo started through inoculative releases according to the National Action Plan for the Control of Dryocosmus kuriphilus, established by the Direção Geral de Alimentação e Veterinária (DGAV), in 2015. This research was carried out during 2018 and 2019, in five chestnut orchards in the Minho region (Northern Portugal). Between January and March 2018, at each location, three monthly harvests of 100 buds were carried out to determine the infestation level. Between April and June 2018, 240 galls were harvested every two weeks, with the purpose of studying the bioecology of D. kuriphilus. In each sampling site, 160 galls were placed in emergence boxes to follow adults of the D. kuriphilus population, and 80 galls were dissected with a binocular magnifying glass, to count and record the evolution of the larval stages of D. kuriphilus and of the parasitoids. The identification of T. sinensis and native parasitoids was carried out. The parasitism rates and Simpson diversity indices were determined. The percentage of buds infested by D. kuriphilus was high in all studied places, varying between 67% and 80%, regardless of the number of T. sinensis releases made and of the chestnut cultivars present in each orchard. The highest rate of parasitism by T. sinensis was 0.5044% and it was recorded in an orchard where there were two releases of T. sinensis in 2016 and 2017 (Arcos de Valdevez—Rio Cabrão—P1). Considering that the exotic parasitoid has already been released in the region since 2016, its establishment in all the chestnut orchards studied was confirmed, although with very low parasitism rates. The natural parasitism associated with the native parasitoid species of D. kuriphilus was confirmed in this work, recording values between 34% and 51% of the parasitized chestnut galls, with 11 species of native parasitoids having been identified: Eupelmus azureos, Eupelmus uruzonus, Eurytoma brunnivientris, Eurytoma pistaciae, Megastigmus dorsalis, Mesopolobus sp., Ormyrus pomaceus, Sycophila biguttata, Sycophila iracemae, Sycophila variegatta and Torymus flavipes.

Assessment performance of Eucalyptus clones attacked by the recent invasion of Leptocybe invasa (Hymenoptera: Eulophidae): Implications to invasion pest management

• Eucalypt materials are sensitive to L. invasa attacks. • Lptocybe invasa causes fewer galls in the Urocam clone. • The Urocam clone can be preferred for use to reduce population growth of L. invasa . Eucalyptus gall wasp, Leptocybe invasa is one of the most important invasive pests of Eucalyptus (Myrtaceae) and has been reported in new cultivation areas worldwide. This pest causes severe damage to susceptible plants of the genus Eucalyptus , where it induces galls in the midribs and petioles of young leaves and the internodes of branch and apices. In this work, we evaluated the response of Eucalyptus clones ( E. urophylla (Urophylla) and two clone hybrids, one of the E. urophylla × E. camaldulensis (Urocam) and other of E. urophylla × E. grandis (Urograndis) crossings.) submitted to L. invasa collected from areas where L. invasa was recently reported. Our results show that the eucalypt materials cultivated in the areas where L. invasa were reported sensitive to L. invasa attacks. However, the wasp causes fewer galls in the Urocam clone. Thus, the Urocam clone can be preferred for use to reduce population growth of L. invasa in Brazilian savannah areas.

A phenological trick and cell wall bricks toward adaptive strategies of Mimosa tenuiflora-Lopesia mimosae interaction in Caatinga environment

Caatinga environment tends to impose constraints on the phenology and development of the host plants and their associated galls. Phenological synchronism in Mimosa tenuiflora-Lopesia mimosae system, and anatomical, cytometric, and immunocytochemical analyzes reveal strategies of the gall survivorship in Caatinga. As phenological strategies, the peak of young galls synchronizes with leaf sprouting in the rainy season, and the reproductive phase is concomitant to gall senescence in the dry season. As structural strategies, the reorganization and the compartmentalization of gall tissues assist gall development in response to environmental constraints, and the predominance of periclinal cell elongation determined the gall bivalve shape. The distribution of pectins, glycoproteins, and hemicelluloses modulate cell walls toward favoring gall resistance to drought stress. The homogalacturonans confer high porosity to the cell walls of the typical nutritive tissue. The galactans and arabinans confer flexibility to the cell walls of the common storage tissue favoring tolerance to drought. The xylogalacturonans and heteromannans in the cell walls of the typical nutritive tissue are associated with nutritive reserves directed to the galling insect. The phenological synchronism, modulation of leaf tissues and cell wall components confer water and nutritional resources to the Lopesia mimosae microenvironment, the gall.

A mismatch in the emergence of Torymus sinensis may affect the effectiveness of this biocontrol agent?

The biocontrol agent Torymus sinensis Kamijo is considered as one of the most successful examples of classical biological control programs. This parasitoid represented a feasible option to obtain sufficient, sustainable, and long-term control of the Asian chestnut gall wasp (ACGW), Dryocosmus kuriphilus Yasumatsu. Recently, an unusual presence of galls was recorded in a few chestnut orchards of Northern Italy, although T. sinensis was released in previous years. We hypothesized that the increase in infestation rate over the years was related to a mismatch in the parasitoid/host phenology, resulting in a decrease in biocontrol effectiveness. Investigations were performed in the five-year period 2018–2022 in six chestnut orchards, selected according to the ACGW infestation level, and divided in two categories: non-critical sites (negligible presence of ACGW galls) and critical sites (high presence of galls with suppression of bud growth). We evaluated T. sinensis’s parasitism rate and phenology by dissecting chestnut galls, comparing non-critical sites versus critical sites. Temperatures were monitored in all the orchards with data loggers. In non-critical sites the parasitism rate by T. sinensis was stable and/or growing in all years, accounting from 77% to 99% (i.e., total number of T. sinensis divided by total number of larval chambers). Conversely, the parasitism rate in critical sites experienced a severe decline, reaching values under 50% in all sites in 2021–2022. Specifically, parasitism on average was reduced by 44% when comparing 2019 versus 2022. The dissection of the galls recorded in non-critical sites in winter (February) highlighted that on average most T. sinensis were larvae and immature pupae (about 70%). Conversely, in critical sites most of the individuals were black mature pupae (76%), with presence of newly formed adults (12%). In 2019–2022, the mean temperature recorded in critical sites was 2.72 °C and 2.34 °C higher in January and February respectively, when compared to non-critical sites. Moreover, in critical sites the early emergence of the biocontrol agent (late February-early March) was recorded when current-year ACGW fresh galls were not available. No variation in the phenological cycle of the ACGW was ever observed, in all sites and years. Our results suggest that the asynchrony between T. sinensis and the ACGW heavily affected the role of the released agent in the suppression of the pest’s outbreaks. Future studies are needed to clarify whether this event is increasing in relevance, also in a climate change perspective.

Latitudinal gradient in species diversity provides high niche opportunities for a range-expanding phytophagous insect.

When species undergo poleward range expansions in response to anthropogenic change, they likely encounter less diverse communities in new locations. If low diversity communities provide weak biotic interactions, such as reduced competition or predation, range-expanding species may experience high niche opportunities. Here, we investigated if oak gall wasp communities follow a latitudinal diversity gradient (LDG) and if lower diversity communities provide weaker interactions at the poles for a range-expanding community member, Neuroterus saltatorius. We performed systematic surveys of gall wasps on a dominant oak, Quercus garryana, throughout most of its range, from northern California to Vancouver Island, British Columbia. On 540 trees at 18 sites, we identified 23 oak gall wasp morphotypes in three guilds (leaf detachable, leaf integral, and stem galls). We performed regressions between oak gall wasp diversity, latitude, and other abiotic (e.g. temperature) and habitat (e.g. oak patch size) factors to reveal if gall wasp communities followed an LDG. To uncover patterns in local interactions, we first performed partial correlations of gall wasp morphotype occurrences on trees within regions). We then performed regressions between abundances of co-occurring gall wasps on trees to reveal if interactions are putatively competitive or antagonistic. Q. garryana-gall wasp communities followed an LDG, with lower diversity at higher latitudes, particularly with a loss of detachable leaf gall morphotypes. Detachable leaf gall wasps, including the range-expanding species, co-occurred most on trees, with weak co-occurrences on trees in the northern expanded region. Abundances of N. saltatorius and detachable and integral leaf galls co-occurring on trees were negatively related, suggesting antagonistic interactions. Overall, we found that LDGs create communities with weaker associations at the poles that might facilitate ecological release in a range-expanding community member. Given the ubiquity of LDGs in nature, poleward range-expanding species are likely moving into low diversity communities. Yet, understanding if latitudinal diversitypattern provides weak biotic interactions for range-expanding species is not well explored. Our large-scale study documenting diversity in a related community of phytophagous insects that co-occur on a host plant reveals that LDGs create high niche opportunities for a range-expanding community member. Biogeographical patterns in diversity and species interactions are likely important mechanisms contributing to altered biotic interactions under range-expansions.

Andricus protuberans Pujade-Villar & Ferrer-Suay IS A SEXUAL FORM (HYM., CYNIPIDAE, CYNIPINI)

We describe and illustrate the morphological characters of the male of Andricus protuberans Pujade-Villar & Ferrer-Suay, 2015 (Hymenoptera, Cynipidae), an oak gall wasp species considered an asexual generation in the original description. The reasons for this mistake are discussed, and the variability of this species in the metasomal segments is mentioned.

The Oriental Chestnut Gall-wasp Dryocosmus Kuriphilus Yasumatsu, 1951, (Hymenoptera: Cynipidae) and Its Introduced and Native Parasitoids in Madeira Island, Portugal, with Notes on Some Other Parasitic Hymenoptera Reared from Gall Samples

The accidental introduction to Madeira of the invasive chestnut gall wasp (CGW), Dryocosmus kuriphilus, is reviewed, as is the subsequent biological control programme implemented by the Regional authorities. This control programme was based on the importation of a non-native parasitoid, Torymus sinensis. Results from five years of parasitoid release are presented, including a list of native parasitoid species associated with D. kuriphilus galls in Madeira. Five species of Hymenoptera are listed as new records for Madeira: Dryocosmus kuriphilus Yasumatsu, 1951; Torymus sinensis Kamijo, 1982; Bootanomyia dorsalis (Fabricius, 1798); Colpoclypeus florus (Walker, 1839), and Ufens foersteri (Kryger, 1918).

Survey of Cynipid Gall Wasps (Hymenoptera, Cynipidae) in Serbia

A list of 72 species of cynipid gall wasps that have been recorded to date in Serbia was compiled on the basis of studying cynipid fauna during the period from 2003 to 2020 and previously published data. The species Andricus quercusramuli (Linnaeus 1761) and Pediaspis aceris (Gmelin 1790) are recorded for the first time in the fauna of Serbia. The fauna of cynipid gall wasps in Serbia has still not been thoroughly studied. It is excepted that about 40 to 50 species new to the fauna will be found.

Discovery through iNaturalist: new species and new records of oak gall wasps (Hymenoptera: Cynipidae: Cynipini) from Texas, USA.

A new species of the genus Druon Kinsey, 1937, D. laceyi Zhang, Sasan OKennon sp. nov. is described on host plant Quercus laceyi Small from central Texas. We also re-establish Andricus lustrans Beutenmller, 1913 comb.rev., and transfer Striatoandricus aciculatus (Beutenmller, 1909) comb. nov. from Andricus. Finally, we report a new state and host record for Druon gregori Melika, Nicholls Stone, 2022. All observations were first shared on the social platform iNaturalist, highlighting the potential of cybertaxonomy in uncovering overlooked biodiversity.

Speciation in Nearctic oak gall wasps is frequently correlated with changes in host plant, host organ, or both.

Quantifying the frequency of shifts to new host plants within diverse clades of specialist herbivorous insects is critically important to understand whether and how host shifts contribute to the origin of species. Oak gall wasps (Hymenoptera: Cynipidae: Cynipini) comprise a tribe of ∼1000 species of phytophagous insects that induce gall formation on various organs of trees in the family Fagacae—primarily the oaks (genus Quercus; ∼435 sp.). The association of oak gall wasps with oaks is ancient (∼50 my), and most oak species are galled by one or more gall wasp species. Despite the diversity of both gall wasp species and their plant associations, previous phylogenetic work has not identified the strong signal of host plant shifting among oak gall wasps that has been found in other phytophagous insect systems. However, most emphasis has been on the Western Palearctic and not the Nearctic where both oaks and oak gall wasps are considerably more species rich. We collected 86 species of Nearctic oak gall wasps from most of the major clades of Nearctic oaks and sequenced >1000 Ultraconserved Elements (UCEs) and flanking sequences to infer wasp phylogenies. We assessed the relationships of Nearctic gall wasps to one another and, by leveraging previously published UCE data, to the Palearctic fauna. We then used phylogenies to infer historical patterns of shifts among host tree species and tree organs. Our results indicate that oak gall wasps have moved between the Palearctic and Nearctic at least four times, that some Palearctic wasp clades have their proximate origin in the Nearctic, and that gall wasps have shifted within and between oak tree sections, subsections, and organs considerably more often than previous data have suggested. Given that host shifts have been demonstrated to drive reproductive isolation between host‐associated populations in other phytophagous insects, our analyses of Nearctic gall wasps suggest that host shifts are key drivers of speciation in this clade, especially in hotspots of oak diversity. Although formal assessment of this hypothesis requires further study, two putatively oligophagous gall wasp species in our dataset show signals of host‐associated genetic differentiation unconfounded by geographic distance, suggestive of barriers to gene flow associated with the use of alternative host plants.

Delimiting the cryptic diversity and host preferences of Sycophila parasitoid wasps associated with oak galls using phylogenomic data.

Cryptic species diversity is a major challenge regarding the species-rich community of parasitoids attacking oak gall wasps due to a high degree of sexual dimorphism, morphological plasticity, small size and poorly known biology. As such, we know very little about the number of species present, nor the evolutionary forces responsible for generating this diversity. One hypothesis is that trait diversity in the gall wasps, including the morphology of the galls they induce, has evolved in response to selection imposed by the parasitoid community, with reciprocal selection driving diversification of the parasitoids. Using a rare, continental-scale data set of Sycophila parasitoid wasps reared from 44 species of cynipid galls from 18 species of oak across the USA, we combined mitochondrial DNA barcodes, ultraconserved elements (UCEs), morphological and natural history data to delimit putative species. Using these results, we generate the first large-scale assessment of ecological specialization and host association in this species-rich group, with implications for evolutionary ecology and biocontrol. We find most Sycophila target specific subsets of available cynipid host galls with similar morphologies, and generally attack larger galls. Our results suggest that parasitoid wasps such as Sycophila have adaptations allowing them to exploit particular host trait combinations, while hosts with contrasting traits are resistant to attack. These findings support the tritrophic niche concept for the structuring of plant-herbivore-parasitoid communities.

Egg maturation in an invasive gall wasp, Dryocosmus kuriphilus (Hymenoptera: Cynipidae): An experimental test of the pro-ovigenic and facultatively synovigenic hypotheses

There are two hypotheses on egg maturation in the invasive chestnut gall wasp, Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae). That it is pro-ovigenic (most or all of its potential lifetime egg complement is mature upon emergence) or facultatively synovigenic (not all eggs are fully developed upon emergence and may be resorbed when suitable hosts are absent). These hypotheses were tested by determining the effects of adult age and food (honey) on egg maturation in D. kuriphilus wasps with no access to host plants. Egg load (the number of mature eggs per female) neither increased nor decreased with adult age in the presence or absence of honey when deprived of host plants. These findings support the pro-ovigenic hypothesis. Some eggs mature during the adult lifetime of cynipoid parasitoids even without hosts, but the cynipoid gall inducer, D. kuriphilus, is pro-ovigenic, probably due to the abundance of chestnut buds available for oviposition under natural conditions. In addition to no competition for oviposition resources, thelytokous reproduction, unintentional introduction of infested chestnut trees and escape from host-specific parasitoids in introduced countries, pro-ovigeny with a high egg load has presumably resulted in D. kuriphilus becoming a global pest of chestnuts. In addition, body length, mesosomal and metasomal lengths and widths, hind femoral length, hind tibial length, and egg load as well as egg width of this wasp were also measured. There was no variation in egg width, but all the other measurements were positively correlated with egg load. Large females of D. kuriphilus had higher egg loads than small females.

A catalogue, revision, and regional perspective of Eastern Palaearctic and Oriental oak gall wasps and their inquilines (Hymenoptera: Cynipidae: Cynipini, Synergini, Ceroptresini).

Recent years have seen rapid advances in the study of Fagaceae-associated gall wasps (Hymenoptera: Cynipidae) of the Eastern Palaearctic and the Oriental (EPO) regions, for both the gall inducing Cynipini (commonly termed oak gall wasps though many species gall non-oak Fagaceae) and the predominantly inquiline tribes Synergini and Ceroptresini. This process has propagated some taxonomic errors and involves many taxa whose taxonomic status is uncertain. To provide a stable foundation for further advance, here we review the taxonomic status of the 212 species (133 oak gall wasps and 79 oak cynipid inquilines) that have been described or recorded in these regions. Of this total, we treat 171 as valid species names (103 oak gall wasps and 68 oak cynipid inquilines) in 20 genera; 22 as synonym names, 13 as incertae sedis, three as nomen dubium, and three as species inquirenda. Callirhytis kunugicola Shinji, 1944 is proposed as syn. nov. of C. kunugicola Shinji, 1943, as Shinji described the same species twice. For all valid species names, we provide taxonomic references, synonyms, and geographical distributions. We summarize what is known of host plant associations and gall locations for gall inducers, and host associations for inquilines. We discuss geographic patterns in the known richness of currently valid species for both groups of organisms, and place this in the context of the biogeography of available Fagaceae host plants. We provide a brief historical review of the study of oak gall wasps and their inquilines in the EPO regions.

Description of Fumariphilus Nieves-Aldrey, gen. nov., a new genus of herb gall wasps, with a key to genera of the tribe Aulacideini (Hymenoptera: Cynipidae).

A new genus of herb gall wasps, Fumariphilus Nieves-Aldrey gen. nov., (Hymenoptera, Cynipidae, Aulacideini), is described. Previous molecular phylogenetic analyses, and resulting systematic changes at the tribe level, have shown that the related species Aylax hypecoi Trotter and Neaylax versicolor Nieves-Aldrey have been incorrectly placed within their respective genera. In order to reflect their monophyletic lineage and to accommodate these species within the tribe Aulacideini, it is necessary to erect a new genus. The two species, Fumariphilus versicolor (Nieves-Aldrey, 1985) n. comb. and Fumariphilus hypecoi (Trotter, 1913) n. comb. placed in the new genus induce galls in fruits of species of, respectively, Hypecoum L. (Papaveraceae: Fumarioideae: Hypecoeae) and Fumaria L. (Papaveraceae: Fumarioideae: Fumarieae), reflecting a host-plant association that is unique among all the cynipids. Diagnostic morphological features of both the adult and the larvae and an identification key to the species of the new genus are provided. Adults of Fumariphilus versicolor n. comb., are also re-described and, for both species of Fumariphilus, the terminal instar larva is described and illustrated with SEM images. Following the erection of the new genus Fumariphilus, Aylax Hartig, sensu Nieves-Aldrey, 1994 is now sufficiently delimited within the tribe Aylacini sensu stricto Ashmead, 1903, which comprises species associated with only plants of the genus Papaver (Papaveraceae). Likewise, Neaylax Nieves-Aldrey, 1994, which now includes only the gall wasp species that associate with species of Salvia (Lamiaceae), is sufficiently delimited within the tribe Aulacideini Nieves-Aldrey, Nylander Ronquist, 2015. Also provided in this work is an updated and illustrated identification key to the genera of the Aulacideini.

Phenology, Density and Parasitism of Asian Chestnut Gall Wasp (Dryocosmus kuriphilus) (Hymenoptera: Cynipidae) in Recently Invaded Chestnut (Castanea spp.) Orchards in Michigan.

Asian chestnut gall wasp (ACGW) (Dryocosmus kuriphilus Yasumatsu), an invasive pest native to China, was detected in Michigan, the largest chestnut producer in North America, in 2015. Along with quantifying gall densities, we tracked dates and cumulative growing degree days corresponding to ACGW life stages in five, seven, and nine orchards in 2017-2019, respectively. Gall formation, triggered by the onset of feeding by overwintered larvae, began soon after bud break. Most adult wasps emerged in mid summer, after pollen production peaked. Density of ACGW in all sites dropped sharply in 2019, probably as a result of larval mortality caused by severely cold temperatures in late January. Gall density was generally lower on Chinese chestnut (Castanea mollisima Blume) trees and C. mollisima hybrids, which share some coevolutionary history with ACGW, than on cultivars of European chestnut (C. sativa Miller) and Japanese-European (C. crenata Sieb. & Zucc. x C. sativa) trees, including the popular Colossal cultivar. Torymus sinensis Kamijo (Hymenoptera: Torymidae), a larval parasitoid previously introduced into the U.S. and several countries in Asia and Europe for ACGW biocontrol, appears to be spreading with ACGW in Michigan. Parasitoid larvae were recorded in four, six, and eight of the infested sites we sampled in 2017-2019, respectively, and parasitism rates ranged from 5 to70% of galls.

Re-establishment of the Nearctic oak cynipid gall wasp genus Druon Kinsey, 1937 (Hymenoptera: Cynipidae: Cynipini), with description of five new species.

The Nearctic cynipid oak gall wasp genus Druon Kinsey comb. rev. is re-established, with 5 new species and 10 species previously placed in the genus Andricus Hartig 1840: D. alexandri Melika, Nicholls Stone, sp. nov., D. flocculentum (Lyon), comb. nov., D. fullawayi (Beutenmller), comb. nov., D. garciamartinonae Pujade-Villar, sp. nov., D. gregori Melika, Nicholls Stone, sp. nov., D. hansoni Cuesta-Porta, Melika Pujade-Villar, sp. nov., D. ignotum (Bassett), comb. nov., D. linaria Kinsey, comb. rev., D. pattoni (Bassett), comb. nov., D. protagion Kinsey, comb. rev. (D. malinum Kinsey, syn. nov., D. polymorphae Kinsey, syn. nov.), D. quercusflocci (Walsh), comb. nov., D. quercuslanigerum (Ashmead), comb. nov., D. receptum Kinsey, comb. rev., D. rusticum Kinsey, comb. rev. and D. serretae Pujade-Villar, Cuesta-Porta Melika, sp. nov.. All species are known only from their asexual generation except for D. ignotum and D. quercuslanigerum, for which alternating asexual and sexual generations are known. The sexual generation of D. ignotum and a new morphological variety of D. quercuslanigerum from Mexico are both described for the first time. We provide descriptions, redescriptions, diagnoses, keys to species, DNA sequence data and analyses, and information on biology, phenology, and distribution. Additionally, four Andricus species with woolly galls and striato-reticulated metasomas are transferred to Striatoandricus Pujade-Villar: S. furnessulus, comb. nov., S. furnessae, comb. nov., S. guatemalensis, comb. nov., and S. tenuicornis, comb. nov.

Evaluation of Eucalyptus Clones for Susceptibility to The Gall Wasp Letocybe invasa Fisher and La Salle

This study investigates the variation among Eucalyptus clones for incidence of gall wasp (Letocybe invasa) and relative changes in biochemical parameters. The three years, and replicated clonal trial involved 14 clones with monthly observations made on the gall wasp incidence. Significant variation was found among the clones, with maximum incidence being in F-316 and relatively the least incidence in C-413, PE-11, PE-14 and C-72. Gall wasp incidence gradually increased from January to April and declined thereafter. The total soluble sugars and phenol content in the infested leaves were found to increase by 49.2 and 22.8% respectively, whereas the protein content decreases (8.8% decrease).

Mini review of the aspects conceptual and taxonomic of Cecidomyiidae Family (Insect: Diptera)

Cecidomyiidae (sometimes misspelled Cecidomyidae) is a family of dipterous known as cecidomids or gall flies, because the larvae of most species feed on plant tissue creating an abnormal growth known as gall. The family has a cosmopolitan distribution, with more than 6,000 species. These insects should not be confused with gall wasps (Cynipidae), which also form galls. The purpose of this article is to obtain information on the characteristics of the Cecidomyiidae (Insecta: Diptera). To this end, a bibliographic survey of Cecidomyiidae was carried out in the years 1961 to 2021. Only complete articles published in scientific journals and expanded abstracts presented at national and international scientific events, Doctoral Thesis and Master's Dissertation were considered. Data were also obtained from platforms such as: Academia.edu, Frontiers, Qeios, Pubmed, Biological Abstract, Publons, Dialnet, World, Wide Science, Springer, RefSeek, Microsoft Academic, Science and ERIC.

Electroantennographic and olfactory responses of Quadrastichus mendeli to eucalyptus volatiles induced by the gall-forming insect Leptocybe invasa.

Although parasitoids can precisely locate hidden gall-inducing insects, the host location mechanism is unknown. In this study, our aim was to clarify the olfactory responses of the parasitoid Quadrastichus mendeli to eucalyptus volatiles induced by the gall wasp Leptocybe invasa. Q. mendeli preferred volatiles from gall-damaged plants compared with those produced by mechanically damaged and undamaged plants. Coupled gas chromatographic-electroantennographic detection results demonstrated that 3-carene, decanal, d-limonene, ethanone,1-(4-ethylphenyl)-, p-cymene and benzene,1-methyl-4-(1-methylpropyl)- from DH 201-2 (Eucalyptus grandis × Eucalyptus tereticornis) elicited significant antennal responses in Q. mendeli in all treatments. Q. mendeli was repelled by decanal and d-limonene and was attracted to 3-carene, benzene,1-methyl-4-(1-methylpropyl)-, ethanone,1-(4-ethylphenyl) and p-cymene. Quaternary blends containing 3-carene, p-cymene, benzene,1-methyl-4-(1-methylpropyl)- and ethanone,1-(4-ethylphenyl)- at a ratio of 1:1:1:1 were attractive to Q. mendeli. However, quaternary blends with added decanal and d-limonene alone or both together induced significant repellence in Q. mendeli. Our report is the first to demonstrate that volatiles produced by galls induced by L. invasa are attractive to Q. mendeli, which suggests that this parasitoid could utilize herbivore-induced plant volatiles to locate its host. The results are beneficial for understanding the function of plant volatiles in host searching by parasitoids of gall-forming insect pests. © 2022 Society of Chemical Industry.

Irrigation and fertilization of Chrysothamnus nauseosus (Asteraceae) affect the attack and gall growth of Rhopalomyia chrysothamni (Cecidomyiidae)

The quality of the environment and the host plant influence the development of the galls as well as the performance of gall inducing insects. The effect of nutrients and water availability on the development of galls induced by Rhopalomyia chrysothamni (Diptera: Cecidomyiidae) on Chrysothamnus nauseosus subsp. hololeucus (Asteraceae) was tested. The study was conducted in a xeric area with no signs of disturbances in Coconino National Forest, Arizona, USA. Individuals of C. nauseosus randomly selected underwent three treatments of water and nutrients availability. At the end of the growing season, the number of attacked plants, abundance and the development of galls in each treatment were evaluated. The differences in habitat quality simulated by the fertility and humidity conditions influenced both the number of attacked plants and the growth of galls. Plants with lower hydric-nutritional quality were more attacked by the galling insect. Otherwise, when both water and nutritional stresses were relieved plants developed galls with higher dry biomass and density. Therefore, this field experimental study indicates that while galling females attacked plants more in xeric environments, the galls grew larger in relatively more mesic conditions. The results showed a trade-off between the quantity and quality of galls of R. chrysothamni depending on the nutritional quality of the host plants.