The Box Tree Moth (BTM), Cydalima perspectalis (Walker) (Lepidoptera: Crambidae), is a major pest of Buxus spp., native to Asia and established in Europe since 2007. It causes severe damage to ornamental and natural boxwood stands, posing a significant risk to protected natural habitats. Given that chemical and microbiological control measures are often restricted or prohibited in these sensitive environments, interest has shifted toward native natural enemies. Among these, tachinid parasitoids represent a viable alternative for sustainable biological control. In this study, we evaluated host acceptance, host-associated mortality, and developmental performance of Exorista larvarum (L.) (Diptera: Tachinidae) on last instar BTM larvae, using the factitious host Galleria mellonella (L.) (Lepidoptera: Pyralidae) as a control. Laboratory bioassays were conducted using no-choice and choice (1:1 and 5:5) experimental designs. Specifically, host acceptance, larval mortality, puparium formation, adult emergence and egg load were quantified. E. larvarum females readily accepted BTM larvae, particularly in the no-choice and choice (5:5) tests, causing high parasitoid-associated mortality (> 70%). However, oviposition frequency and subsequent developmental success were significantly lower on BTM than on G. mellonella. In both choice tests, parasitoid females exhibited a marked preference for the factitious host. Furthermore, while the development of E. larvarum on BTM was constrained, a limited number of adults successfully emerged, demonstrating, for the first time, that complete development on BTM is occasionally possible. Although our laboratory findings provide promising evidence of the suppressive potential of E. larvarum against BTM, its actual field-scale efficacy remains to be validated. Nevertheless, it deserves consideration as a viable component of augmentative and conservation biological control programmes, especially in sensitive habitats where conventional control methods are restricted.

IntroductionUrban green spaces require planting strategies that simultaneously enhance biodiversity, reduce maintenance inputs, and improve resilience to climate change. Herbaceous perennial mixtures represent promising alternatives to conventional lawns and simplified ornamental plantings, although their long-term performance under low-input management remains insufficiently documented. This study evaluated the suitability of different perennial mixtures for sustainable urban landscaping, focusing on vegetation performance, management requirements, ornamental value, and insect biodiversity.MethodsTwelve mixtures of ornamental perennial species were evaluated over three consecutive years under field conditions in northwestern Italy, without irrigation or fertilization. Plant performance was assessed through ground cover, weed suppression, ornamental quality, and flowering dynamics. In 2023–2024, carabid beetles and butterflies were monitored as bioindicator groups to assess the potential contribution of the experimental area to insect biodiversity.ResultsPerennial mixture significantly affected vegetation performance, with marked differences in establishment and persistence. Mixtures dominated by Stachys byzantina, Sedum reflexum, Carex flacca, Festuca glauca ‘Elijah Blue’, Phlox subulata, Sedum spurium ‘John Creech’, and Geranium × cantabrigiense ‘Karmina’ rapidly achieved stable canopy closure (>89%), maintained high ornamental quality (>81%), and effectively suppressed weeds. Conversely, mixtures lacking persistent canopy-forming species showed poor establishment, limited ground cover, and greater weed biomass. Flowering was strongly seasonal, peaking in late spring, while mixtures containing complementary flowering taxa provided more continuous floral resources. Biodiversity monitoring recorded 6,897 carabid beetles and 2,271 butterflies, with insect abundance showing pronounced seasonal variation. Species of conservation interest, including Lycaena dispar and Lucanus cervus, were also recorded.DiscussionFunctional composition, rather than species richness alone, emerged as a key determinant of perennial mixture performance by influencing canopy development, weed suppression, ornamental quality, and habitat structure. Combining flowering-rich mixtures that provide seasonally complementary floral resources with structurally persistent, weed-suppressive vegetation may therefore represent an effective strategy for simultaneously supporting pollinators and ground-dwelling arthropods. Trait-based perennial mixtures can provide resilient, biodiversity-friendly, and low-maintenance solutions for climate-adapted urban green infrastructure.

Ambrosia beetles (Coleoptera: Curculionidae, Scolytinae and Platypodinae) constitute a group of wood-boring insects relying on symbiotic fungi to exploit weakened trees. Some invasive species can also colonise healthy hosts, posing risks to forests. We investigated how environmental drivers may affect the ambrosia beetle community in two valleys in NW Italy. Over a two-year monitoring period (2024-2025), 48 ethanol-baited traps were placed in sites with chestnut as the dominant species: cultivated and managed chestnut orchards and mixed environments with assorted tree composition. In total, 118,286 individuals were collected representing six species, with Xyleborinus saxesenii (Ratzeburg) dominating the assemblage. Three non-native species were found, namely Anisandrus maiche (Kurentsov), Xylosandrus crassiusculus (Motschulsky) and Xylosandrus germanus (Blandford). The geographic structure of the two valleys and their climatic context were the main factors shaping the beetle assemblage, while local drivers acted as secondary elements. The Pesio Valley exhibited higher alpha diversity and more invasive species, likely linked to the high presence of 'bridge hosts' and a more humid climate. Moreover, a specific association between chestnut-dominant environments and invasive species, such as X. germanus and A. maiche, was found. This study suggested that while chestnut orchards serve as important ecological refuges, their vulnerability to biological invasions may be mediated by specific local conditions. Further investigations are needed over a longer period to evaluate how local habitat conditions may act as a hint of the seasonal population trend of the beetle community, also in a climate change perspective.

Field surveys were carried out to deepen knowledge about the ambrosia beetle community in sweet chestnut‐producing areas in north‐west Italy. They were carried out in areas where Castanea sativa is the dominant species, using ethanol‐baited black cross‐vane traps, from March to October over a 2‐year period (2023–2024). A total of 42 180 individuals including four genera and six species were trapped, with Xyleborinus saxesenii (Ratzeburg) representing more than 90% of all the specimens. The other species found included: Anisandrus dispar (F.), Xyleborus monographus (F.), Xylosandrus crassiusculus (Motschulsky) and Xylosandrus germanus (Blandford) . In addition to these species which were already known to be present in the surveyed area, Anisandrus maiche Kurentzov was collected for the first time. Although the ambrosia beetle community recorded in most cases did not raise particular concern among chestnut growers, a strong increase in their abundance was recorded in 2024. Specifically, while most species have more than doubled their presence, X. monographus and X. germanus have increased more than 10‐fold. Owing to the economic and environmental value of chestnut and since ambrosia beetles are known to be significantly influenced by climatic factors, specific investigations are needed over time to evaluate whether their presence is actually increasing, particularly in the context of climate change.

The issue of sexual size dimorphism (SSD) variation is relevant due to the identification of mechanisms by which animals adapt to changing environmental conditions. Using the database of the ground beetle Carabus granulatus, compiled from measurements of more than 8000 individuals, we estimated the nature of size variation in beetles captured in different parts of their range, including most of Russia and Europe. ANOVA showed that the sizes of both females and males vary statistically significantly across regions, although not always to the same extent. Therefore, SSD values were assessed not only for each sample by region as a whole, but also for each of the six studied traits (for C. granulatus as a whole), as well as the variability of SSD values for each trait in each of the 13 studied populations. SSD was the highest in the southern regions of the species’ range (Bulgaria, Italy) and decreased monotonically northward. The highest SSD values were recorded for elytra length and pronotum width (0.08–0.09), while for the others, they were significantly lower (0.05). Methodological and ideological issues in assessing and applying SSD data in animal populations are discussed.

We evaluated the richness, diversity, and assemblage of Carabidae in the Val Grande National Park. Monitoring, by pitfall-trapping, was performed in 2021-2022 in two sites (S1 and S2), and considering six vegetation habitats ("Terraced ferns", "Terraced grassland", "Wood", "Chestnut grove", "Ecotone", and "Grassland"). A total of 2707 carabids consisting of 34 species were collected. The assemblage displayed the dominance of Calathus fuscipes graecus (27%), followed by Carabus glabratus latior (15%), and Carabus problematicus problematicus (15%). Besides the species already known for the Park, seven further species have been recorded. While in S1 the carabid assemblage was unexpectedly poor, a rich biodiversity with an excellent balance among the numerous brachypterous, macropterous, and pteropolymorphous species was recorded in S2. The species recorded in the habitat "Terraced ferns" and in "Ecotone" constituted the dominant groups and they accounted for 51% and 41%, in S1 and S2, respectively. The awareness of the species composition, richness, and ecology can be a useful tool for the Park to address the management of the surfaces in order to avoid disturbing the carabid fauna, especially for carabids of conservation concern, to mitigate their potential decline.

Recent outbreaks of the invasive alien species Cydalima perspectalis (Walker, 1859) (Lepidoptera: Crambidae) have led to the widespread loss of boxwoods in Europe. Although details on its biology are not fully unraveled, the box tree moth (BTM) can be considered a major pest, severely damaging its primary host, Buxus sempervirens, ultimately affecting the associated coenosis. In European environments, box trees form the Habitat 5110, and BTM outbreaks are seriously endangering its long-term survival.The effectiveness of microbiological treatments with Bacillus thuringiensis var. kurstaki (Btk) on the survival of BTM was evaluated in field and controlled conditions. Given the scant specificity of Btk action, an in-depth survey of its potential impact on non-target diurnal Lepidoptera has been conducted by monitoring their communities’ changes in treated and control areas.Btk spraying was highly effective in the field, and five days after treatments larval density reduction was over 90% in all sites and years, with similar mortality trends achieved in controlled conditions.No significant short-term effects were detected either on non-target diurnal lepidopterans’ abundance or species richness.These results can be combined with the outcomes of spatially explicit models to overcome issues that, up to now, have caused the failure of appropriate strategies to control C. perspectalis. Even if no impact has been observed on non-target Lepidoptera, a rigorous plan for the application, detection and surveillance of the potential effects of microbiological treatments needs to be established.

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.

The pine processionary moth (PPM), Thaumetopoea pityocampa (Denis and Schiffermüller), is one of the most economically important forest defoliators in southern Europe. This pest is a univoltine oligophagous insect species, and the genus Pinus represents its main host. Investigations were carried out in the five-year period 2016–2020 in NW Italy. PPM males were monitored using commercial funnel traps baited with sex pheromone. The infestation index was recorded by counting the number of nests per tree. Temperature and rainfall were automatically recorded by 94 georeferenced meteorological stations. Adult presence was evaluated as the maximum number of captured individuals in a day, total captures during the season, the Julian day at max captures, or at first or last captures. Environmental variables (altitude, cumulative rain, and cumulative degree-days) and biological parameters were summarized using principal component analysis. Our study showed that the analyzed variables contribute to driving and affecting the PPM population dynamics, which also exhibited a year-to-year decrease. Due to the environmental and sanitary importance, all the data collected about the PPM will be useful to develop predictive risk models, as to deploy countermeasures in a timely and cost-effective manner.

Investigations on the egg parasitoid complex of the pine processionary moth (PPM), Thaumetopoea pityocampa, were performed in 2020-2022 in seven sites located in NW Italy to determine the parasitoid species composition, seasonal emergence, parasitoid species incidence, and parasitism rate. Furthermore, we examined whether the egg batches parameters and the parasitism rate were influenced by altitude and summer temperatures. A sample of 832 egg batches was collected, each batch consisting on average of 206 +/- 5.73 eggs. In total, 35,881 egg parasitoids emerged, mainly represented by four primary species, namely Ooencyrtus pityocampae, Baryscapus servadeii, Anastatus bifasciatus and Trichogramma sp.. Parasitism ranged from 4.27% to 24.41% and the most representative species were O. pityocampae (68.38%) in 2020-2021, and Trichogramma sp. (56.50%) in 2021-2022. The altitude of the sites (808-1303 m a.s.l.) had a negative correlation with all the investigated egg batches parameters (e.g. batch length), and with the parasitism rate by A. bifasciatus and B. servadeii, while a positive correlation was found only for O. pityocampae. The number of days with temperatures above 30 degrees C was positively correlated with parasitism rate for A. bifasciatus and O. pityocampae, and negatively for Trichogramma sp., while no correlation was found with B. servadeii. Since the performance and distribution of the natural enemies is highly dependent on climatic conditions, the regulating effect of parasitoids, reducing PPM population needs to be further investigated, to compare the complex of natural enemies across a wider geographic and climatic range.

Non-native invasive arthropod species threaten biodiversity and food security worldwide, resulting in substantial economic, environmental, social and cultural costs. Classical biological control (CBC) is regarded as a cost-effective component of integrated pest management programmes to manage invasive arthropod pests sustainably. However, CBC programmes are traditionally conducted once a pest has established in a new environment, and invariably all research needed to achieve approval to release a biological control agent can take several years. During that time, adverse impacts of the pest accelerate. A pre-emptive biocontrol approach will provide the opportunity to develop CBC for invasive pests before they arrive in the country at risk of introduction and therefore enhance preparedness. A critical aspect of this approach is that risk assessment is carried out in advance of the arrival of the pest. Implementing pre-emptive biocontrol risk assessment means that natural enemies can be selected, screened in containment or abroad and potentially pre-approved prior to a pest establishing in the country at risk, thus improving CBC effectiveness. However, such an approach may not always be feasible. This contribution defines the fundamental prerequisites, principles, and objectives of pre-emptive biocontrol risk assessment. A set of guidelines and a decision framework were developed, which can be used to assess the feasibility of conducting a pre-emptive risk assessment for candidate biological control agents against high-risk arthropod pests.

The fall armyworm (Spodoptera frugiperda) is a major pest native to the Americas, recently invading Africa, Asia and Oceania, severely affecting maize and other crops. Control efforts mainly involve chemical pesticides, posing public health risks. Classical biological control has not been implemented in the invaded regions, though some native parasitoids have adapted to the pest. In the Americas, various parasitoids and predators attack S. frugiperda. The egg parasitoid Telenomus remus, successful in the Americas, is already present in Africa and Asia. Key potential biological control agents include Chelonus insularis, an egg-larval parasitoid with high parasitism rates; Eiphosoma laphygmae, a specific larval parasitoid; and Campoletis spp., larval parasitoids that may be suitable for cooler regions. Other promising parasitoids include Aleoides laphygmae, Cotesia marginiventris, Archytas marmoratus and Lespesia archippivora. Further investigation into these parasitoids could enhance biological control strategies in newly invaded areas.

The spotted lanternfly (Lycorma delicatula; SLF), a planthopper native to China and south east Asia, has spread to South Korea, Japan and the USA, causing significant economic damage to agriculture and forests. Feeding on over 100 plant species, SLF exudes sap that promotes mold growth and is a nuisance due to its aggregating behavior. Research on natural enemies for biological control has identified several promising candidates. In China, the egg parasitoid Anastatus orientalis and the nymphal parasitoid Dryinus sinicus show potential, with A. orientalis demonstrating high parasitism rates but variable specificity. In the USA, the egg parasitoid Ooencyrtus kuvanae, initially used for spongy moth control, has been found in SLF egg masses, though its broad host range and potential as a hyperparasitoid may limit its suitability. Further research is necessary to fully evaluate these natural enemies for effective biological control of SLF.

The red necked longicorn (RNL), Aromia bungii (Coleoptera: Cerambycidae), originates from eastern Asia and has become an invasive pest in Japan, Germany and Italy. Predominantly attacking stone fruit trees (Prunus spp.), RNL larvae tunnel within the cambium layer, disrupting sap flow and potentially killing the host tree. The pest poses a significant threat to both fruit production and wood production. It is considered a quarantine species in Europe, capable of spreading through wood products and plants for planting. There has been no classical biological control implemented against RNL. However, potential natural enemies include the generalist parasitoids Sclerodermus guani and Sclerodermus harmandi (Hymenoptera: Bethylidae). S. guani has shown a parasitism rate of 43% in laboratory studies and has been used in China for controlling forest pests. Other potential natural enemies include generalist predators and parasitoids, such as Dastarcus helophoroides (Coleoptera: Bothrideridae), which has been used in combination with entomopathogenic nematodes for biological control in China, and species of Braconidae and Ichneumonidae. Despite their potential, the broad host range of these natural enemies raises concerns about non-target effects.

Arrival, establishment, and further dispersal of non‐native natural enemies are considered essential for a successful biological control programme, while among the factors that may determine the success of such a programme, genetic diversity of the introduced population plays an important role in the establishment of a non‐native species. The Chinese parasitoid wasp Torymus sinensis Kamijo (Hymenoptera: Torymidae) was initially released in Europe in Italy to control biologically the Asian chestnut gall wasp Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae), and reduce the damage induced on sweet chestnut ( Castanea sativa Miller). In the following years, T. sinensis was then released in numerous other European countries as a biological control agent of D. kuriphilus . Its presence has also been reported beyond the countries of release due to rapid natural dispersal. To assess the post‐release genetic diversity of D. kuriphilus , we screened T. sinensis populations from six European countries and tested the possibility of these populations suffering from frequently observed genetic effects that could threaten its successful establishment in Europe. Our results exhibit that T. sinensis populations have suffered neither from the Allee effect nor from genetic bottleneck after their release and establishment in Europe, something that increases the possibility to effectively control D. kuriphilus in Europe.

The 2-lined chestnut borer (Agrilus bilineatus) is a pest native to eastern North America, affecting oak (Quercus spp.) and chestnut (Castanea spp.). The larvae feed under the bark, leading to tree death within one to four years. While primarily a secondary pest attacking stressed trees, it can affect healthy trees during outbreaks. Recently established in Turkey, it poses a significant threat to European oak and chestnut species. There is no history of classical biological control against A. bilineatus. The parasitoid Phasgonophora sulcata, native to North America, shows potential as a biological control agent but is not species-specific. Other natural enemies, including various parasitoids and predators, have been identified, but their effectiveness and associations with A. bilineatus require further research. The potential for significant impact in Europe and the EPPO region underscores the need for monitoring and possible control measures if the pest spreads.

The bronze birch borer (BBB), Agrilus anxius, is a significant pest native to North America, affecting birch trees (Betula spp.). Its larvae burrow through the cambial layer, causing tree decline and mortality, especially in stressed North American birches and healthy European and Asian birches. Although endemic in North America, BBB has caused widespread damage, particularly in urban areas and during droughts. The pest poses a potential threat to European and Asian birch forests if it were to spread. Currently, there is no history of classical biological control against BBB. Several natural enemies, including egg and larval parasitoids, such as Thysanus sp., Atanycolus charus and Phasgonophora sulcata, have been identified in North America, but their role in controlling BBB populations is unclear. Other natural enemies, including various parasitoid species and a microsporidian, have shown limited potential. Oobius agrili, a parasitoid used against emerald ash borer (EAB), can parasitize BBB ova, but is less effective when EAB ova are present. Further research is needed to identify and evaluate potential biological control agents for BBB.

The spotted wing Drosophila, (Drosophila suzukii) native to East Asia, has become an invasive species in Hawaii, USA, since 1980 and has spread globally, affecting economically important crops, such as berries and cherries. The high reproductive rate and polyphagous nature of this species, facilitated by a unique serrated ovipositor, lead to significant crop damage and economic losses. Control measures, including insecticides and biological controls, have limited effectiveness due to frequent re-infestations. Research in Asia identified 3 promising parasitoid species for classical biological control, i.e. Ganaspis brasiliensis, Leptopilina japonica and Asobara japonica. Among them, G. brasiliensis (particularly genetic group G1) shows the highest host specificity to D. suzukii and has been approved for release in several regions. Other parasitoids, such as Trichopria drosophilae and Pachycrepoideus vindemiae, have limited field effectiveness. Classical biological control using specific parasitoids offers a potential solution to reduce D. suzukii populations and mitigate economic damage.

Bactericera cockerelli, a psyllid, is a major agricultural pest affecting potatoes, tomatoes and other crops through feeding damage and transmission of the bacterial pathogen Liberibacter solanacearum, which causes zebra chip disease. This pest, originating from the Western USA, Mexico and Central America, poses a threat in its native regions and in New Zealand where it has been introduced. Given the current distribution, B. cockerelli could establish itself in Southern and Central Europe and areas with mild winters in Northern Europe. Tamarixia triozae, a parasitoid wasp, has shown promise as a biological control agent, with established populations in New Zealand achieving up to 40% parasitism rates. T. triozae prefers fourth and fifth instar nymphs of B. cockerelli and has high reproductive potential, although it requires carbohydrate sources, such as nectar for optimal reproduction. Sensitivity to insecticides and the timing of parasitism may limit its effectiveness in some scenarios. Other natural enemies, including generalist predators, could also be explored for classical biological control in regions lacking these natural predators.

The oak processionary moth (Thaumetopoea processionea>) is native to Central and Southern Europe and has been spreading to Northern Europe, including Southern England since 2006. The larvae feed on various oak species (Quercus spp.), contributing to oak decline and causing significant health issues for humans and pets due to their urticating hairs. There is no history of classical biological control for this pest, but several promising natural enemies exist. The most promising natural enemies include the larval parasitoids Carcelia iliaca and Pales processioneae, which are specific to Thaumetopoea spp. and have been dominant in Germany and the Netherlands, with C. iliaca also found in invasive UK populations. The egg parasitoid Ooencyrtus masii is noted in Italy but seems less significant than other polyphagous species, such as Anastatus bifasciatus and Trichogramma spp. Pimpla processioneae and other Pimpla species are frequently found parasitizing pupae, with P. processioneae being the most specific. Other natural enemies such as A. bifasciatus, the larval parasitoid Meteorus versicolor, and various tachinid parasitoids are abundant but too polyphagous for classical biological control programs.