Developmental stages and gut microenvironments influence gut microbiota dynamics in the invasive beetle Popillia japonica Newman (Coleoptera: Scarabaeidae).

Popillia japonica Newman (Coleoptera: Scarabaeidae) is a highly polyphagous invasive beetle originating from Japan. This insect is highly resilient and able to rapidly adapt to new vegetation. Insect-associated microorganisms can play important roles in insect physiology, helping their hosts to adapt to changing conditions and potentially contributing to an insect's invasive potential. Such symbiotic bacteria can be part of a core microbiota that is stably transmitted throughout the host's life cycle or selectively recruited from the environment at each developmental stage. The aim of this study was to investigate the origin, stability and turnover of the bacterial communities associated with an invasive population of P. japonica from Italy. Our results demonstrate that soil microbes represent an important source of gut bacteria for P. japonica larvae, but as the insect develops, its gut microbiota richness and diversity decreased substantially, paralleled by changes in community composition. Notably, only 16.75% of the soil bacteria present in larvae are maintained until the adult stage. We further identified the micro-environments of different gut sections as an important factor shaping microbiota composition in this species, likely due to differences in pH, oxygen availability and redox potential. In addition, P. japonica also harboured a stable bacterial community across all developmental stages, consisting of taxa well known for the degradation of plant material, namely the families Ruminococcacae, Christensenellaceae and Lachnospiraceae. Interestingly, the family Christensenallaceae had so far been observed exclusively in humans. However, the Christensenellaceae operational taxonomic units found in P. japonica belong to different taxonomic clades within this family.

'Candidatus Phytoplasma phoenicium' associated with almond witches'-broom disease: from draft genome to genetic diversity among strain populations.

BACKGROUND: Almond witches'-broom (AlmWB), a devastating disease of almond, peach and nectarine in Lebanon, is associated with 'Candidatus Phytoplasma phoenicium'. In the present study, we generated a draft genome sequence of 'Ca. P. phoenicium' strain SA213, representative of phytoplasma strain populations from different host plants, and determined the genetic diversity among phytoplasma strain populations by phylogenetic analyses of 16S rRNA, groEL, tufB and inmp gene sequences. RESULTS: Sequence-based typing and phylogenetic analysis of the gene inmp, coding an integral membrane protein, distinguished AlmWB-associated phytoplasma strains originating from diverse host plants, whereas their 16S rRNA, tufB and groEL genes shared 100 % sequence identity. Moreover, dN/dS analysis indicated positive selection acting on inmp gene. Additionally, the analysis of 'Ca. P. phoenicium' draft genome revealed the presence of integral membrane proteins and effector-like proteins and potential candidates for interaction with hosts. One of the integral membrane proteins was predicted as BI-1, an inhibitor of apoptosis-promoting Bax factor. Bioinformatics analyses revealed the presence of putative BI-1 in draft and complete genomes of other 'Ca. Phytoplasma' species. CONCLUSION: The genetic diversity within 'Ca. P. phoenicium' strain populations in Lebanon suggested that AlmWB disease could be associated with phytoplasma strains derived from the adaptation of an original strain to diverse hosts. Moreover, the identification of a putative inhibitor of apoptosis-promoting Bax factor (BI-1) in 'Ca. P. phoenicium' draft genome and within genomes of other 'Ca. Phytoplasma' species suggested its potential role as a phytoplasma fitness-increasing factor by modification of the host-defense response.

Morphological characterization of the antenna of Torymus sinensis (Hymenoptera: Torymidae) and a comparison within the superfamily Chalcidoidea.

The parasitoid Torymus sinensis (Hymenoptera: Torymidae) has been successfully used in Italy since 2005 for biological control of the invasive cynipid Dryocosmus kuriphilus (Hymenoptera: Cynipidae), highly destructive for the economically relevant Castanea sativa (Fagales: Fagaceae). In order to investigate the morphological aspects related to sensorial behavior, a fine morphology study of the antennae and their sensilla was conducted by scanning electron microscopy on both sexes of T. sinensis. The antennae, composed of a scape, a pedicel and a flagellum with ten flagellomeres, had chaetic sensilla of six subtypes, placoid sensilla of three subtypes, trichoid sensilla, sensilla with a roundish grooved tip, and coeloconic sensilla. The chaetic sensilla of the first three subtypes were found in the scape and in the pedicel, and those of the last three subtypes, together with trichoid, roundish grooved tip and coeloconic sensilla, were found only on flagellomeres. Sexual dimorphism was detected in the morphology of the proper pedicel and the flagellum, and in the presence and distribution of the sensilla and their subtypes. The morphological aspects of the antenna of T. sinensis and of its sensilla were compared with those found in the family Torymidae and in other families of the extremely diverse superfamily Chalcidoidea.

Description of Calling, Courtship and Mating Behaviour of Six Species of the Genus Zyginidia (Auchenorrhyncha: Cicadellidae).

The vibrational communication and mating behaviour of the graminicolous leafhoppers Zyginidia pullula, Z. ribauti, Z. scutellaris, Z. serpentina, Z. sohrab, and Z. biroi were investigated to explain why the first five species hybridize. Z. biroi was used as a control species. All species behaved in the same way and no significant statistical differences were detected with regard to male calls, while female calls and the male courtship song differed in Z. biroi, thus showing that a specific pre-mating isolation mechanism was used by the latter species and the first five ones lacked such a mechanism. In addition, Z. sohrab is missing in Italy, while the other species live allopatrically in Italy, with the only exceptions being Z. serpentina and Z. biroi, which live in Sicily and are often found in sympatry, and Z. scutellaris and Z. biroi, which live in Sardinia. All these species can be distinguished by means of male genital appendages; however, Z. biroi is longer and has a different body colour. The existence of natural hybrids of Z. pullula, Z. ribauti, and Z. scutellaris in the Italian peninsula and their hybridization in the laboratory with Z. serpentina and Z. sohrab require the investigation of possible post-mating reproductive barriers before re-considering their systematic validity.

First record of the non-native Osbornellusauronitens (Provancher, 1889) (Hemiptera, Cicadellidae, Deltocephalinae) in Italy.

Background: Globalisation and international trade, in particular, are the major drivers of introduction and the spread of non-native species. To date, more than 30 species of non-native Hemiptera Auchenorrhyncha have been accidentally introduced into Europe. Some species are invasive with important repercussions primarily for agricultural activities, while almost no information exists on their impacts within natural ecosystems. Therefore, early detection of non-native species and their subsequent monitoring are extremely important actions to undertake. New information: The North American Osbornellusauronitens (Provancher, 1889), firstly recorded for the Palearctic and Europe in Switzerland in 2016, is recorded in Italy for the first time on the basis of 77 specimens collected between August 2015 and October 2022.

Popillia japonica - Italian outbreak management.

Popillia japonica, a priority pest for the EU, was first detected in Northern Italy in 2014. Since its discovery, the outbreak extended over an area of more than 16,000 square kilometers in Northern Italy and Southern Switzerland. In this review, we summarize the state-of-the-art of research conducted in Italy on both the spreading capacity and control measures of P. japonica. Chemical, physical, and biological control measures deployed since its detection are presented, by highlighting their strengths and weaknesses. An in-depth study of the ecosystems invaded by P. japonica disclosed the presence and pathogenicity of natural strains of entomopathogenic fungi and nematodes, some of which have shown to be particularly aggressive towards the larvae of this pest under laboratory conditions. The Plant Health authorities of the Lombardy and Piedmont regions, with the support of several research institutions, played a crucial role in the initial eradication attempt and subsequently in containing the spread of P. japonica. Control measures were performed in the infested area to suppress adult populations of P. japonica by installing several traps (e.g., for mass trapping, for auto-dissemination of the fungus Metarhizium anisopliae, and "attract & kill"). For larval control, the infested fields were treated with commercial strains of the entomopathogenic fungus M. anisopliae and nematode Heterorhabditis bacteriophora. Future studies will aim at integrating phenological and spread models developed with the most effective control measures, within an ecologically sustainable approach.

Horizontal transmission of the symbiotic bacterium Asaia sp. in the leafhopper Scaphoideus titanus Ball (Hemiptera: Cicadellidae).

BACKGROUND: Bacteria of the genus Asaia have been recently recognized as secondary symbionts of different sugar-feeding insects, including the leafhopper Scaphoideus titanus, vector of Flavescence dorée phytoplasmas. Asaia has been shown to be localized in S. titanus gut, salivary glands and gonoducts and to be maternally transmitted to the progeny by an egg smearing mechanism. It is currently not known whether Asaia in S. titanus is transmitted by additional routes. We performed a study to evaluate if Asaia infection is capable of horizontal transmission via co-feeding and venereal routes. RESULTS: A Gfp-tagged strain of Asaia was provided to S. titanus individuals to trace the transmission pathways of the symbiotic bacterium. Co-feeding trials showed a regular transfer of bacterial cells from donors to recipients, with a peak of frequency after 72 hours of exposure, and with concentrations of the administrated strain growing over time. Venereal transmission experiments were first carried out using infected males paired with uninfected females. In this case, female individuals acquired Gfp-labelled Asaia, with highest infection rates 72-96 hours after mating and with increasing abundance of the tagged symbiont over time. When crosses between infected females and uninfected males were conducted, the occurrence of "female to male" transmission was observed, even though the transfer occurred unevenly. CONCLUSIONS: The data presented demonstrate that the acetic acid bacterial symbiont Asaia is horizontally transmitted among S. titanus individuals both by co-feeding and venereal transmission, providing one of the few direct demonstrations of such a symbiotic transfer in Hemiptera. This study contributes to the understanding of the bacterial ecology in the insect host, and indicates that Asaia evolved multiple pathways for the colonization of S. titanus body.

Adaptation of indigenous larval parasitoids to Tuta absoluta (Lepidoptera: Gelechiidae) in Italy.

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a serious threat to tomato (Solanum lycopersicum L.) crops in South America. In Europe, after its first detection in Spain in 2006, it rapidly spread through the Mediterranean basin, reaching Italy 2 yr later. The aim of our work was to find indigenous effective biological control agents and to evaluate their potential role in the control of larval populations of T. absoluta in controlled conditions. Nine species of larval parasitoids emerged from field-collected tomato leaves infested by T. absoluta. The most abundant, Necremnus near artynes (Walker) and Necremnus near tidius (Walker) (Hymenoptera: Eulophidae), were tested in laboratory parasitism trials. Furthermore, because the species N. artynes and N. tidius are each reported in literature as an ectoparasitoid of Cosmopterix pulchrimella Chambers (Lepidoptera: Cosmopterigidae) on upright pellitory plants, olfactometer bioassays were performed to assess the response of our parasitoids to the odors of tomato and pellitory leaves infested by T absoluta and C. pulchrimella, respectively, compared with healthy ones. Both Necremnus species showed good adaptation to the invasive pest, and we observed a high larval mortality of T. absoluta because of host feeding and parasitism. Even olfactory responses highlighted a preference of both wasps for tomato plants infested by the exotic pest. These preliminary results demonstrated a high suitability of these indigenous natural enemies for controlling T. absoluta. Further investigations are needed to confirm their role as potential biological agents in commercial tomato plantations.

Assessment of Chestnut Gall Toughness: Implications for a Biocontrol Agent.

(1) Torymus sinensis, the biocontrol agent of the Asian chestnut gall wasp Dryocosmus kuriphilus, is univoltine, but in NW Italy a small percentage of individuals exhibits a prolonged diapause, mainly as late instar larva. (2) In 2020, the diapause was investigated to evaluate its trend over the years. Due to the low survival rate of diapausing T. sinensis adults, the seasonal variation in the galls' toughness was evaluated, thus assuming that dry galls over time can negatively affect emergence. The window of vulnerability of the gall wasp galls was also evaluated in controlled conditions. (3) The results showed that the average number of second year T. sinensis emerging per 100 cells was 0.41 ± 0.05, and dead adults accounted for 4.1 ± 0.23 per 100 cells. Gall toughness resulted in lower values for galls collected in May and June, and then gradually increased over time. In general, no difference was detected in the wall toughness of galls formed during the previous year when compared to current-year dry galls. Oviposition was recorded on all the tested galls collected in May and June, and no difference in the number of oviposition events was detected. Conversely, no oviposition was observed in July. Comparing the number of oviposition events by T. sinensis and the gall toughness, a negative correlation was found (R2 = -0.99). (4) The present findings contribute descriptive information on this gall's structural traits, and the influence on gall wasp management is also discussed.

'Candidatus Liberibacter europaeus' sp. nov. that is associated with and transmitted by the psyllid Cacopsylla pyri apparently behaves as an endophyte rather than a pathogen.

'Candidatus Liberibacter spp.' cause serious plant diseases. 'Candidatus Liberibacter asiaticus', 'Ca. L. americanus' and 'Ca. L. africanus' are the aetiological agents of citrus greening (Huanglongbing) in Asia, America and Africa. 'Candidatus Liberibacter solanacearum' causes diseases in Solanaceae in America and New Zealand. All four species are vectored by psyllid insects of different genera. Here, we show that the pear psyllid pest Cacopsylla pyri (L.) hosts a novel liberibacter species that we named 'Ca. Liberibacter europaeus'. It can bloom to high titres in the psyllid host, with more than 10(9) 16S rRNA gene copies per individual. Fluorescent in situ hybridization experiments showed that 'Ca. L. europaeus' is present in the host midgut lumen, salivary glands and Malpighian tubules. 'Candidatus L. europaeus' has a relatively high prevalence (> 51%) in C. pyri from different areas in the Piedmont and Valle d'Aosta regions in Italy and can be transmitted to pear plants in experimental transmission trials. However, even though high titres of the bacterium (more than 10(8) 16S rRNA gene copies g(-1) of pear plant tissue) could be detected, in the pear tissues no specific disease symptoms could be observed in the infected plants over a 6-month period. Despite liberibacters representing potential quarantine organisms, 'Ca. L. europaeus', first described in Italy and Europe, apparently behaves as an endophyte rather than a pathogen.

The yeast Wickerhamomyces anomalus (Pichia anomala) inhabits the midgut and reproductive system of the Asian malaria vector Anopheles stephensi.

While symbiosis between bacteria and insects has been thoroughly investigated in the last two decades, investments on the study of yeasts associated with insects have been limited. Insect-associated yeasts are placed on different branches of the phylogenetic tree of fungi, indicating that these associations evolved independently on several occasions. Isolation of yeasts is frequently reported from insect habitats, and in some cases yeasts have been detected in the insect gut and in other organs/tissues. Here we show that the yeast Wickerhamomyces anomalus, previously known as Pichia anomala, is stably associated with the mosquito Anopheles stephensi, a main vector of malaria in Asia. Wickerhamomyces anomalus colonized pre-adult stages (larvae L(1)-L(4) and pupae) and adults of different sex and age and could be isolated in pure culture. By a combination of transmission electron microscopy and fluorescent in situ hybridization techniques, W. anomalus was shown to localize in the midgut and in both the male and female reproductive systems, suggesting multiple transmission patterns.

Bacterial endosymbiont localization in Hyalesthes obsoletus, the insect vector of Bois noir in Vitis vinifera.

One emerging disease of grapevine in Europe is Bois noir (BN), a phytoplasmosis caused by "Candidatus Phytoplasma solani" and spread in vineyards by the planthopper Hyalesthes obsoletus (Hemiptera: Cixiidae). Here we present the first full characterization of the bacterial community of this important disease vector collected from BN-contaminated areas in Piedmont, Italy. Length heterogeneity PCR and denaturing gradient gel electrophoresis analysis targeting the 16S rRNA gene revealed the presence of a number of bacteria stably associated with the insect vector. In particular, symbiotic bacteria detected by PCR with high infection rates in adult individuals fell within the "Candidatus Sulcia muelleri" cluster in the Bacteroidetes and in the "Candidatus Purcelliella pentastirinorum" group in the Gammaproteobacteria, both previously identified in different leafhoppers and planthoppers. A high infection rate (81%) was also shown for another symbiont belonging to the Betaproteobacteria, designated the HO1-V symbiont. Because of the low level of 16S rRNA gene identity (80%) with the closest relative, an uncharacterized symbiont of the tick Haemaphysalis longicornis, we propose the new name "Candidatus Vidania fulgoroideae." Other bacterial endosymbionts identified in H. obsoletus were related to the intracellular bacteria Wolbachia pipientis, Rickettsia sp., and "Candidatus Cardinium hertigii." Fluorescent in situ hybridization coupled with confocal laser scanning microscopy and transmission electron microscopy showed that these bacteria are localized in the gut, testicles, and oocytes. As "Ca. Sulcia" is usually reported in association with other symbiotic bacteria, we propose that in H. obsoletus, it may occur in a bipartite or even tripartite relationship between "Ca. Sulcia" and "Ca. Purcelliella," "Ca. Vidania," or both.

Different mosquito species host Wickerhamomyces anomalus (Pichia anomala): perspectives on vector-borne diseases symbiotic control.

The genetic manipulation of the microbial community associated with hematophagus insects is particularly relevant for public health applications. Within mosquito populations, this relationship has been overlooked until recently. New advances in molecular biotechnology propose the genetic manipulation of mosquito symbionts to prevent the transmission of pathogens to humans by interfering with the obligatory life cycle stages within the insect through the use of effector molecules. This approach, defined as 'paratransgenesis', has opened the way for the investigation and characterization of microbes residing in the mosquito body, particularly those localised within the gut. Some interesting bacteria have been identified as candidates for genetic modification, however, endosymbiotic yeasts remain largely unexplored with little information on the symbiotic relationships to date. Here we review the recent report of symbiotic relationship between Wickerhamomyces anomalus (Pichia anomala) and several mosquito vector species as promising methods to implement control of mosquito-borne diseases.

Models Applied to Grapevine Pests: A Review.

This paper reviews the existing predictive models concerning insects and mites harmful to grapevine. A brief conceptual description is given on the definition of a model and about different types of models: deterministic vs. stochastics, continuous vs. discrete, analytical vs. computer-based, and descriptive vs. data-driven. The main biological aspects of grapevine pests covered by different types of models are phenology, population growth and dynamics, species distribution, and invasion risk. A particular emphasis is put on forecasting epidemics of plant disease agents transmitted by insects with sucking-piercing mouthparts. The most investigated species or groups are the glassy-winged sharpshooter Homalodisca vitripennis (Germar) and other vectors of Xylella fastidiosa subsp. fastidiosa, a bacterium agent of Pierce's disease; the European grape berry moth, Lobesia botrana (Denis and Schiffermuller); and the leafhopper Scaphoideus titanus Ball, the main vector of phytoplasmas agents of Flavescence dorée. Finally, the present and future of decision-support systems (DSS) in viticulture is discussed.

Pheromone-Mediated Mating Disruption as Management Option for Cydia spp. in Chestnut Orchard.

(1) Background: Pheromone-based devices are successfully used to control insect pests in agriculture. (2) Methods: Investigations were conducted to evaluate the effectiveness of mating disruption (MD) to control the chestnut tortrix moths, Cydia fagiglandana and Cydia splendana. Surveys were performed in northern Italy in 2019-2020. MD was carried out using the pheromone dispenser Ecodian® CT. The effectiveness of MD was assessed by recording male adult catches in pheromone-baited sticky traps and larvae in chestnut fruits, comparing MD and control plots. (3) Results: The total number of trapped males was significantly lower in MD plots than in control ones, for all sites and years. Trap catch suppression in MD plots averaged 89.5% and 93.8% for C. fagiglandana and 57.4% and 81% for C. splendana in 2019 and 2020, respectively. The larval infestation rate in fruits did not vary between plots except for one site where a reduction of about 71% in the MD plot was recorded in 2019. (4) Conclusions: Low catches in MD plots turned out to be a good measure of the effectiveness of communication disruption, but no satisfactory data have been obtained regarding fruit infestation, highlighting how the reduction of male catches cannot always be considered as a reliable indicator of successful control. Specific investigations about background population density, dispersal and mating/oviposition behavior are thus essential for a viable management strategy.

An integrated transcriptomic and proteomic approach to identify the main Torymus sinensis venom components.

During oviposition, ectoparasitoid wasps not only inject their eggs but also a complex mixture of proteins and peptides (venom) in order to regulate the host physiology to benefit their progeny. Although several endoparasitoid venom proteins have been identified, little is known about the components of ectoparasitoid venom. To characterize the protein composition of Torymus sinensis Kamijo (Hymenoptera: Torymidae) venom, we used an integrated transcriptomic and proteomic approach and identified 143 venom proteins. Moreover, focusing on venom gland transcriptome, we selected additional 52 transcripts encoding putative venom proteins. As in other parasitoid venoms, hydrolases, including proteases, phosphatases, esterases, and nucleases, constitute the most abundant families in T. sinensis venom, followed by protease inhibitors. These proteins are potentially involved in the complex parasitic syndrome, with different effects on the immune system, physiological processes and development of the host, and contribute to provide nutrients to the parasitoid progeny. Although additional in vivo studies are needed, initial findings offer important information about venom factors and their putative host effects, which are essential to ensure the success of parasitism.

Compartmentalization of bacterial and fungal microbiomes in the gut of adult honeybees.

The core gut microbiome of adult honeybee comprises a set of recurring bacterial phylotypes, accompanied by lineage-specific, variable, and less abundant environmental bacterial phylotypes. Several mutual interactions and functional services to the host, including the support provided for growth, hormonal signaling, and behavior, are attributed to the core and lineage-specific taxa. By contrast, the diversity and distribution of the minor environmental phylotypes and fungal members in the gut remain overlooked. In the present study, we hypothesized that the microbial components of forager honeybees (i.e., core bacteria, minor environmental phylotypes, and fungal members) are compartmentalized along the gut portions. The diversity and distribution of such three microbial components were investigated in the context of the physico-chemical conditions of different gut compartments. We observed that changes in the distribution and abundance of microbial components in the gut are consistently compartment-specific for all the three microbial components, indicating that the ecological and physiological interactions among the host and microbiome vary with changing physico-chemical and metabolic conditions of the gut.

Molecular evidence for multiple infections as revealed by typing of Asaia bacterial symbionts of four mosquito species.

The recent increased detection of acetic acid bacteria (AAB) of the genus Asaia as symbionts of mosquitoes, such as Anopheles spp. and Aedes spp., prompted us to investigate the diversity of these symbionts and their relationships in different mosquito species and populations. Following cultivation-dependent and -independent techniques, we investigated the microbiota associated with four mosquito species, Anopheles stephensi, Anopheles gambiae, Aedes aegypti, and Aedes albopictus, which are important vectors of human and/or animal pathogens. Denaturing gradient gel electrophoresis (DGGE) analysis based on the 16S rRNA gene revealed the presence of several bacterial taxa, among which Asaia sequences were among the dominant in most of the samples. A collection of 281 Asaia isolates in cell-free media was established from individuals belonging to the four species. The isolates were typed by internal transcribed spacer (ITS)-PCR, tRNA-PCR, BOX-PCR, and randomly amplified polymorphic DNA (RAPD)-PCR, revealing that different Asaia strains are present in different mosquito populations, and even in single individuals.

Acetic acid bacteria, newly emerging symbionts of insects.

Recent research in microbe-insect symbiosis has shown that acetic acid bacteria (AAB) establish symbiotic relationships with several insects of the orders Diptera, Hymenoptera, Hemiptera, and Homoptera, all relying on sugar-based diets, such as nectars, fruit sugars, or phloem sap. To date, the fruit flies Drosophila melanogaster and Bactrocera oleae, mosquitoes of the genera Anopheles and Aedes, the honey bee Apis mellifera, the leafhopper Scaphoideus titanus, and the mealybug Saccharicoccus sacchari have been found to be associated with the bacterial genera Acetobacter, Gluconacetobacter, Gluconobacter, Asaia, and Saccharibacter and the novel genus Commensalibacter. AAB establish symbiotic associations with the insect midgut, a niche characterized by the availability of diet-derived carbohydrates and oxygen and by an acidic pH, selective factors that support AAB growth. AAB have been shown to actively colonize different insect tissues and organs, such as the epithelia of male and female reproductive organs, the Malpighian tubules, and the salivary glands. This complex topology of the symbiosis indicates that AAB possess the keys for passing through body barriers, allowing them to migrate to different organs of the host. Recently, AAB involvement in the regulation of innate immune system homeostasis of Drosophila has been shown, indicating a functional role in host survival. All of these lines of evidence indicate that AAB can play different roles in insect biology, not being restricted to the feeding habit of the host. The close association of AAB and their insect hosts has been confirmed by the demonstration of multiple modes of transmission between individuals and to their progeny that include vertical and horizontal transmission routes, comprising a venereal one. Taken together, the data indicate that AAB represent novel secondary symbionts of insects.

Palaearctic Egg Parasitoids Interaction to Three Grapevine Exotic Pests in Northwestern Italy: A New Association Involving Metcalfa pruinosa.

The most important exotic leafhopper pests currently affecting the Italian vineyards are the leafhoppers Scaphoideus titanus, Orientus ishidae and the planthopper Metcalfa pruinosa. Their highest population density is detected in the uncultivated areas with wild grapevines. Should these habitats be considered only a problem or a potential resource for Palearctic entomophagy of these three exotic pests? The aim of this work was to study the biotopes and biocoenosis present in the Piedmontese vineyard agroecosystem, evaluating the parasitization rate and other crucial aspects for a possible application in biological control. Several specimens of egg-parasitoid wasps were obtained from filed-collected two-year-old grapevine canes. The most prevalent one belonged to the Oligosita collina group (Trichogrammatidae) emerged only from M. pruinosa eggs with a parasitization rate of over 40%. The new association is the first report of such a high level of parasitization on the flatid planthopper. The parasitization rate mainly relied on the host egg density and the abundance of plants suitable for the oviposition. A second parasitoid generation on the overwintering eggs is discussed, as well as other hypothesis. Furthermore, the parasitization rate was higher than the one showed by the dryinid Neodryinus typhlocybae, the control agent introduced in Italy under the biological control strategy, highlighting a possible implication in this biocoenosis. We assume that the egg parasitoid adaptation may contribute to M. pruinosa control.