Cameraria Ohridella Research Articles

The influence of abiotic factors on the development of caterpillars of the chestnut transient moth (Cameraria ohridella Deschka & Dimic) in laboratory conditions

Goal. To investigate the effect of abiotic factors on the duration of development of the caterpillars of the chestnut transient moth, and the ability of the caterpillars to penetrate another leaf of bitter chestnut in laboratory conditions. Methods. In laboratory conditions, experiments were conducted to determine the duration of development of moth caterpillars at temperatures of 15, 20, 25, 30°C, with and without illumination. Chestnut moth caterpillars of different ages were previously selected in natural conditions. In the laboratory, they were placed in thermostats according to their age (10 specimens each), and kept at the appropriate temperature until pupation. To test their ability to re-penetrate the leaves, caterpillars of different ages were removed from the primary leaf and planted on another. Artificial lighting was applied (round the clock) using 4 fluorescent lamps PHILIPS TLD18W/54-765 with a power of 18 W. The experiment was repeated 10 times. Accounting was carried out daily. Statistical processing of data was carried out according to generally accepted methods. Results. During the experiment, it was determined that moth caterpillars are not able to re-enter another chestnut leaf. During the study of the influence of abiotic factors on the duration of the development of caterpillars, it became known that under a temperature regime of 15°C and without lighting, their survival is significantly lower than with lighting. In conditions of complete darkness, 24.4% of the pest was frightened, and with lighting — 58.8%. At the same time, the results of the experiment also showed the importance of the effect of the temperature regime on the maintenance of these insects. Thus, the greatest death of caterpillars was recorded at a temperature of 15°C, when the temperature increased to 20—25°C, this indicator gradually decreased, but when the holding temperature increased to 30°C, the death rate increased again. Thus, we came to the conclusion that it is possible to keep the chestnut moth in laboratory conditions only during the period of its seasonal activity in nature. It is at this time that it becomes possible to study it more thoroughly, and to search for ecological means to reduce the number of chestnuts. Conclusions. Chestnut moth caterpillars are not able to re-enter another chestnut leaf, and their full development is possible only inside mines, where there are optimal conditions for this. The greatest mortality of young caterpillars in laboratory conditions was observed at storage temperatures of 15 and 30°С. The optimal temperature regime for this stage of pest development is 20—25°C. Therefore, keeping these caterpillars in laboratory conditions is effective only during the period of their seasonal activity in nature.

Stakeholder exposure to and knowledge of tree pests and diseases and their management in urban areas

Urban trees and forests provide many benefits to the urban environment and are important for climate change adaptation. Yet, they are increasingly threatened by insect pests and diseases, hereafter tree pests/diseases. There is little evidence of the risk awareness and knowledge of different urban stakeholders of this growing threat, how they are affected by tree pests/diseases, and how they might respond to it. To fill this gap, we undertook an online survey of different key stakeholder groups associated with urban trees and forests in Germany. A majority of 75.8 % of the 186 respondents consider urban tree pests/diseases a severe problem and 51.1 % reported high knowledge of tree pests/diseases. There was a lack of knowledge of certain reportable quarantine pests/diseases (e.g., canker stain of plane, emerald ash borer, Xylella) and pest/disease management options (e.g., manual treatment methods and tree diversification). Respondents were most affected by the horse chestnut leafminer (61.3 %), ash dieback (58.1 %) and oak processionary moth (50.0 %). The most widely used pest remedial measures were improvements of tree living conditions (60.8 %) and purchases of plants from certified or trusted local sources (59.7 %). Multiple correspondence analysis showed a significant association between levels of knowledge of tree pests/diseases and pest management responses (11.7 %). Our results suggest that future efforts to improve urban tree health should be enhanced and tailored to the different requirements of various stakeholder groups. The findings of this first comprehensive study with a purely urban focus will inform the development of future activities that prevent or reduce the spread of tree pests/diseases in urban areas. Data AvailabilityThe survey respondents did not give permission for the full data to be accessed or used by third parties.

Persistence of imidacloprid in trunk injected horse chestnut and its impact on Cameraria ohridella (Lepidoptera: Gracillariidae)

Persistence of imidacloprid in trunk injected horse chestnut and its impact on Cameraria ohridella (Lepidoptera: Gracillariidae)

Morphophysiological features of the generative offspring of Aesculus hippocastanum L. from various ecologically unfavorable areas of an industrial city

The results of the influence of various ecological conditions of an industrial city (environmentally favorable zone, zones of motor vehicle emissions and metallurgical production, damage by the chestnut miner Cameraria ohridella Deschka & Dimič) on the functional state of the generative offspring of Aesculus hippocastanum L. were given. The average degree of the mass variability of the horse chestnut seeds was revealed, the level of which depended on the type of pollution. Higher values of the variation coefficient were established in seeds from monitoring sites ecologically unfavorable for plant growth. A decrease in the mass of ripe seeds of horse chestnut exposed to the effects of vehicle emissions, metallurgical production, and the severe attack of the chestnut moth C. ohridella was shown compared to samples from an ecologically favorable zone. It was found that the moisture loss in seeds from the ecologically favorable zone was on average 25.0 %, while from the main road zone – 15.2 %. A decrease in the content of storage proteins by an average of 14.5 % in the zones of anthropogenic pollution was observed. The largest values of this characteristics were shown by most trees from the ecologically favorable zone. In the seeds of A. hippocastanum plants, an increase in the activity of both benzidine peroxidase and catalase was established mainly under the effects of aerotechnogenic pollution. The level of enzyme activity depended on the type of phytotoxic emissions. A decrease in the activity of benzidine peroxidase was registered due to the effects of motor vehicle emissions, and an increase due to the effects of metallurgical production. A significant increase in catalase activity was found in the seeds of A. hippocastanum trees from two monitoring sites and, especially, under the influence of vehicle emissions, which can be explained by a compensatory reaction in response to reduced peroxidase activity. An individual reaction of the studied protein system (storage proteins, antioxidant enzymes) of the seeds of some trees was observed, regardless of the stress level of technogenic load and the type of pollutants. At each monitoring site, trees whose seeds had both increased and significantly decreased enzyme activity were identified. In the Botanical Garden and in the park near the metallurgical enterprise, the seeds of only one of three trees showed high activity of both peroxidase and catalase. Considering the physiological functions of the studied enzymes in the seeds and the reaction of the plant organism to biotic and abiotic stresses, the increase in the activation of catalase and peroxidase indicated their participation in antioxidant protection against active forms of oxygen to ensure a reduction in the intensity of damage processes in the generative offspring of A. hippocastanum L. The variability of the level of enzyme activity in horse chestnut seeds means adaptation to environmental conditions and, in general, reveals the adaptive ability of generative offspring to germinate due to the high antioxidant potential to counteract the development of oxidative stress under the influence of adverse environmental factors. It was concluded that the chronic influence of adverse factors of the urban environment causes the formation of individual seeds with increased antioxidant protection characteristics, which can be used as planting material when creating sustainable plantations in an industrial city.

Инструментальный мониторинг дехромации листвы каштана конского обыкновенного при повреждении охридским минером

A comparison of the visual and instrumental assessments of the horse chestnut foliar dechromation degree infested by the Ohrid miner (Cameraria ohridella) was carried out. The data of surveys of model trees for the period 2014–2022 in the Moscow region are compared. A statistically reliable regression relationship between the results of visual and instrumental assessment of dechromation in a long-term series of observations is shown. Instrumental monitoring of the leaves damages during the growing season was carried out based on the assessment of the NDVI vegetation index using the GreenSeeker Handheld® (Trimble) device. The seasonal dynamics of the NDVI index of foliage under Ohrid miner damage is presented on the example of the 2021 season. It is shown that the plants affected by the pest have a shorter growing season, and the average NDVI index for the season is 25...30 % lower than that of undamaged plants. In a nine-year series of observations, it was found that the transition of the NDVI index over the threshold value of 0.4 in plants affected by the Ohrid miner is observed on average 30...40 days earlier than in healthy plants. The possibility of assessing foliage dechromation based on the results of hyperspectral imaging without visualization using the Ocean Insight «Flame» spectrometer is considered. It is shown that the spectral characteristics of the reflectivity of healthy and damaged Ohrid miner leaves differ significantly, which was demonstrated by comparing the spectral brightness curves of reflection. Characteristic spectral zones in the visible and near infrared ranges have been identified, according to which the presence of leaf damage by a miner is successfully identified. It was found that in the near-infrared radiation area, the reflection of damaged leaves are significantly lower than that of healthy leaves, which indicates a decrease in the overall water content of chestnut leaf blades when damaged by pests. According to the results of multi- and hyperspectral surveys, it is possible to automatically determine the lesion of the horse chestnut foliage by the leaf-mining pest Cameraria ohridella.

A new host plant for Cameraria ohridella Deschka & Dimic, 1986 (Lepidoptera: Gracilleriidae)

The article deals with the study of host plants of Cameraria ohridella Deschka & Dimic, 1986, especially focusing on Belarus findings. For the first time, Acer saccharinum L., is recorded as a host plant. The cases of damaging other plants by this species as well as relationships of Gracillariidae with the plant family Sapindaceae are summarized.

Циркуляция грибов в системе конский каштан обыкновенный (Aesculus hippocastanum) – каштановая минирующая моль (Cameraria ohridella) на территории г. Саратова

The article presents data on the detection of mould fungi in the system of Aesculus hippocastanum – Cameraria ohridella which is an invasive pest of chestnuts. Entomological and mycological studies were conducted using standard methods . The study determined the species composition, occurrence index and quantitative indicators of the micromycetes present in the leaf tissues of Aesculus hippocastanum and Cameraria ohridella caterpillars. 135 samples of the caterpillars of three generations of the insects, the mines and the healthy plant leaves collected at the permanent observation points in Saratov city (Astrakhanskaya St., Bolshaya Sadovaya St., Naberezhnaya Kosmonavtov St.) were analysed. 18 species of the fungi of the genera Alternaria, Aspergillus, Cladosporium, Fusarium, Penicillium and Rhizopus were identified. Numerical indicators of fungi ranged from 102 to 105 CFU/g. There was an increase in the quantitative indicators and species diversity of micromycetes during the vegetation period. Aspergillus was the dominant genus of fungi in the first generation of insects, Alternaria dominated in the second generation, and Cladosporium dominated in the third generation. Thus, Ochrid myner can be a natural reservoir of various fungi, including phytopathogenic ones.

Phenolic-Based Discrimination between Non-Symptomatic and Symptomatic Leaves of Aesculus hippocastanum Infested by Cameraria ohridella and Erysiphe flexuosa.

The herbivore Cameraria ohridella (kingdom Animalia) and the pathogen Erysiphe flexuosa (kingdom Fungi) are considered pests and biotic stressors of Aesculus hippocastanum (chestnut trees). The impact of both pests on the accumulation of secondary metabolites in chestnut leaves was investigated. Specifically, the interactive effect of both pests on metabolite accumulation and their potential role in enhancing the resistance of chestnut trees to biological stress was the focus of this study. Aesculus hippocastanum leaves with varying degrees of Cameraria ohridella infestation and Erysiphe flexuosa infection were used in this research. Leaf samples were collected during the plant vegetative growth phase and evaluated for pest infection and secondary metabolite content. Eight main polyphenols were identified in the leaves: (1) neochlorogenic acid, (2) (-)-epicatechin, (3) procyanidin trimer A-type, (4) procyanidin tetramer A-type, (5) quercetin-3-O-arabinoside, (6) quercetin-3-O-rhamnoside, (7) kaempferol-3-O-arabinoside, and (8) kaempferol-3-O-rhamnoside. It was found that the accumulation of metabolites, primarily those derived from epicatechin and quercetin, during the initial vegetation phase (up to 11.05 or 09.05), strongly depended on the later degree of pest infection. The differences observed in the metabolite dynamics in the chestnut leaves, depending on the extent of infection, indicate the development of a metabolic response mechanism in chestnut trees to biological stress.

Dominant pests and pathogens of urban plantings in Kyiv: Species composition and prevalence

Impact of pests and pathogens on trees, along with air pollution, are one of the most important factors that determine tree health in parks, squares, boulevards and streets of Kyiv. The purpose of the study was to monitor populations of dominant pests and foci of pathogens of tree ornamental plantings in Kyiv from 2020 to 2022. The objects of the study were horse chestnut leaf miner Cameraria ohridella Deschka & Dimic., leaf blotch miner moth Acrocercops brongniardella F., Linden gall mite Eriophyes tiliae Nal., and powdery mildew of Common Oak Erysiphe alphitoides Griffon & Maubl. U. Braun&S. Takam. Using the route method and the E.E. Geschele scale, population indicators were evaluated for Cameraria ohridella, Acrocercops brongniardella and Eriophyes tiliae. It is found that the number of these species is increasing. It is showed that these pests are common on tree species Aesculus hippocastanum L., Quercus robur L., and Tilia cordata Mill., in street and urban plantings under the intense influence of abiotic and anthropogenic factors. In 2021, compared to 2020, the prevalence of Cameraria ohridella increased by 7 times, the distribution of Acrocercops brongniardella ranged from 76-78%, and powdery mildew damage to Common Oak, on average, is 3.41. According to the results of the study, it is identified that the populations of Acrocercops brongniardella and Eriophyes tiliae are in a stable condition and do not have substantial deviations by year, while the invasive species Cameraria ohridella is characterised by a substantial increase in prevalence and abundance, which means that it causes an intense weakening and decrease in the decorative effect of Chestnut in the city’s street plantings. Annual intensive powdery mildew Erysiphe alphitoides damage was noted at young ordinary plantings of Common Oak along the main roads of the metropolis. The potential reproduction opportunities of phytophagous insect populations are analysed. In practice, the obtained results can be used for pest management and further monitoring of tree health in street and urban plantings in Kyiv

Effect of Sun Exposure of the Horse Chestnut (Aesculus hippocastanum L.) on the Occurrence and Number of Cameraria ohridella (Lepidoptera: Gracillariidae)

The study of the leafmining moth of the chestnut miner (Cameraria ohridella Deschka & Dymić, 1986) was carried out through the planting of the common horse chestnut (Aesculus hippocastanum L.) in the Main Botanical Garden of the Russian Academy of Sciences. The effect of various degrees of insolation of horse chestnut plants on leaf morphology and the composition of secondary metabolites, as well as the relationship of these parameters with the number and density of C. ohridella populations during the growing season, was studied. The solar influence, it was noted, had a significant impact. Thus, the largest number of the pests was recorded on the leaves of the sunlit side of the tree crown, and the smallest on the leaves of the shady part of the crown. The low content of polyphenols in the pool of secondary metabolites in the tissues of the A. hippocastanum leaves did not deter C. ohridella and poorly protected the plants from this miner, while the significant content of carbohydrates in the leaves reduced the resistance of chestnut plants to damage by the Ohrid leaf miner.

Impact analysis of different applications of cyantraniliprole on control of horse chestnut leaf miner (Cameraria ohridella) larvae supported by biophoton emission

Cameraria ohridella is one of the most invasive pests of horse chestnut. Cyantraniliprole is one of the most perspectively active insecticides, which can transport within the plant in several ways, and its efficacy against this pest has not yet been tested. All three modes of application were effective against the target pest, but there was a difference in the time of action between them. However, no demonstrable difference in the speed of action was detected between the doses used. A more intense rate of acropetal translocation was confirmed compared to basipetal translocation. A trend-like effect between the applied concentration of cyantraniliprole and the photon emission intensity per unit area of plant tissue was observed in the translaminar and acropetal treatment settings. In both cases, a clear increase in photon emission was observed, indicating metabolic upregulation. Therefore, we can conclude that biophoton emission measurements can be utilized to conduct efficient pesticide translocation investigations.

Yeasts associated with mines on tree leaves in the urban areas.

Mines on tree leaves and undamaged leaves were studied to investigate yeast complexes in urban areas (Aesculus hippocastanum, miner - Cameraria ohridella; Betula verrucosa, miner - Caloptilia betulicola; Populus nigra, miner - Lithocolletis populifoliella; Quercus robur, miner - Tischeria companella; Salix caprea, miner - Trachys minuta; Syringa vulgaris, miner - Caloptilia syringella; Tilia cordata, miner - Phyllonorycter issikii; Ulmus laevis, miner - Carpatolechia fugitivella). The abundance and taxonomic structure of yeasts were studied using a surface plating method on solid media (GPY agar). Identification of yeast species was based on the ITS rDNA nucleotide sequence. The average abundance of yeasts during the first stages of mine formation in the internal tissues of leaves was 103cfu/g. After 23-25days, during the last stage of larval metamorphosis before mine destruction, the abundance of yeasts in the mines increased by two orders of magnitude to 105cfu/g. No significant differences were observed in the abundance of yeasts in mines formed by different insects on different trees. A total of twelve yeast species were observed. The fast-growing ascomycetous yeasts Hanseniaspora uvarum and H. occidentalis dominated the mines. On undamaged leaves, the basidiomycetous yeasts Papiliotrema flavescens and Rhodotorula mucilaginosa, typical in the phyllosphere, dominated. The opportunistic yeast Candida parapsilosis was detected in the yeast complexes of all mines examined and was not found on the surface of leaves. Comparison of the relative abundance of yeast species between the studied mines and undamaged leaves using principal component analysis showed that all studied yeast communities in the mines were significantly different from the epiphytic yeast complexes of the undamaged leaves. Thus, miners in urban environments provoke the formation of short-lived endophytic yeast complexes with high abundance of Hanseniaspora. For leaf miners, the yeasts serve primarily as a food source for insect larvae rich in vitamins and amino acids. The adult leaf miners, in turn, contribute to the reproduction of the yeasts and create favorable conditions for their development.

Harmful entomofauna in forestry and green infrastructure

The national invention of the forests of the Republic of Srpska established over 100 species, with the entire volume of wood mass being dominated by deciduous trees (beech 45%, oak 8%, other deciduous trees 7%, tribal deciduous trees 3%). Beech has the largest share in state forests in the supplies (43%), followed by fir about 20%, and spruce by 16%. Of the harmful endomofauna of fir, one third are gradeogenic species, which can cause great economic and environmental damage. Harmful endomofauna of beech number 32 species, of which economically significant primary species are prone to mass occurrences and trophical relations related to the leaf (15.75% of species). Harmful endomofauna of oak species represent 40 most common species. Outbreaking primary species make up one quarter, feed predominantly on leaves and cause defoliation (50%). Harmful for seeds or acorns are 15% of pests, which can have a detrimental effect on the reproduction and regeneration of oak forests. The most common pests in spruce forests are species that occur frequently and can only occasionally cause minor damage (56.25%). The most economically important are bark beetles and wood borers, which tend to outbreak (12.5%) and cause dammage on a hudge area. Outbreaking species are also pest of seed and cones, which participate in the spruce pest complex with 14.58%. Pests in nurseries are important for reproduction in forestry and for providing nursery stock for the establishment of green infrastructure. Of the 54 harmful species, almost a quarter are non-native species (24.07%). Often, non-native pests are transferred from nurseries to public green spaces, green corridors, and entrepreneurs are ofteen serving as a pathway for introduction of non-native harmful species into forest ecosystems. Therefore, ornamental plants are rightly considered the most important pathways for introduction of invasive alien species in mannaged and protective forests. Non-native and invasive species that are introduced in the Republic of Srpska e.g. emerging pests are folowing: Aproceros leucopoda, Cameraria ohridella, Corythucha arcuata, Corythucha ciliata, Cydalima perspectalis, Eopineus strobi, Gillettella cooleyi, Leptoglossus occidentalis, Metcalfa pruinosa, Obolodiplosis robiniae, Phyllonorycter platani, Pseudaulacaspis pentagona, Stictocephala bisonia etc. Most of these species are pests in nurseries and ongreen infrastructure. Some native insect species appear as emerging pests due to their increase of population , as an answer to changing weather conditions. One example is the ash wasp Tomostethus nigritus (F.) (Hymenoptera: Tenthredinidae), which in the last ten years appear in local outbreaks in tree lines or other green areas at the territory of Southeastern Europe from the Balkan Peninsula to the Nordic countries. Increased populations of Zeuzera pyrina (Lepidoptera: Cossidae) were also applied in nurseries and on elements of green infrastructure. Due to the climate change, the species Ovalisia (Palmar) festiva migrated from the Mediterranean area, setting a dangerous pest in nurseries, while the linden bug Oxycarenus lavaterae is common on lindens, building large colonies but so far with no significant damage on trees. In order to prevent introduction and stop the spread of alien invasive species, there is need to ensure the maintenance of a high level of health protection status in agriculture, green infrastrucrure and forestry.

Invasion Genetics of the Horse-Chestnut Leaf Miner, Cameraria ohridella (Lepidoptera: Gracillariidae), in European Russia: A Case of Successful Involvement of Citizen Science in Studying an Alien Insect Pest

Based on the intensive monitoring conducted by our team and volunteers in 2021, the secondary range of an alien horse-chestnut leaf miner, Cameraria ohridella Deschka & Dimić, 1986 (Lepidoptera: Gracillariidae), was specified in European Russia. This invasive pest was confirmed in 24 out of 58 administrative regions of Russia, which it has occupied for approximately 16 years. Analysis of the COI mtDNA gene sequenced in 201 specimens collected in 21 regions of the European part of Russia indicates the occurrence of two haplotypes (A and B), which are also present in the secondary range of C. ohridella in Eastern and Western Europe. The haplotype A dominated and was present in 87.5% of specimens from European Russia. In 2021, C. ohridella produced spectacular outbreaks in Aesculus hippocastanum in southern Russia, where it damaged more than 50% of the leaves in trees in 24 out of 30 distant localities. In the south of the country, the pest infested Acer pseudoplatanus, whereas other species of Acer of European, East Asian, and North American origin showed no signs of attacks. Taking into account that Ae. hippocastanum is present in most regions of European Russia, we expect a further range expansion of C. ohridella up to the Ural Mountains.

THE MAIN FACTORS INFLUENCING THE DAMAGE AND POPULATION DYNAMICS OF CAMERARIA OHRIDELLA (DESCHKA & DIMIC, 1986) IN URBAN PLANTATIONS OF KYIV REGION

In Ukraine, the horse-chestnut leaf-miner (Lepidoptera: Gracillariidae, Cameraria ohridella Deschka & Dimic, 1986) was first discovered in 2002 in the Lviv region. Currently, the species is widespread in Ukraine and its range continues to expand. The consequence of the life activity of the miner lies in severe damage to the leaves and premature defoliation, negatively affecting the accumulation of reserves of nutrients necessary to maintain the vitality of plants in the winter and restore growth in the spring. The article provides data on the first detection and further spread of the invasive pest of horse-chestnuts C. ohridella in the world and on the territory of Ukraine. The phytosanitary condition of horse-chestnut trees (Aesculus hippocastanum L.) in the conditions of urban plantations in Makariv town, Buchansky district, Kyiv region in 2022 was studied. The data of the seasonal dynamics of the number of the pest, tracked with the help of pheromone monitoring, are given. In the course of route surveys of horse chestnut plantations, the phytosanitary condition of the trees on both sides of the road in the city of Makariv along Dmitriy Rostovsky Street and on the territory of the Makariv Lyceum No. 1 was assessed according to the following criterias: damage to the crown, the degree of damage to the leaf plates, and the overall vitality of the trees. The condition of each tree was assessed with a certain number of points according to the appropriate methods. According to the conducted surveys, it was found that the trees that were located on the isolated territory of the Lyceum suffered less damage from the phytophagus during the month and had significantly higher vitality and decorativeness, compared to the horse-chestnuts that grew along the road. Phytophage pheromone monitoring showed that the number of C. ohridella recorded in traps on both sides of the roadway on Dmitry Rostovsky Street significantly exceeded the number of insects caught on the territory of the educational institution. A clear inverse relationship between the number of insects caught and meteorological conditions was established: during heavy rains with high air humidity, the flight of the chestnut miner almost completely stopped, and the number of insects in the traps was close to zero, and vice versa.

Green areas state assessment within the urban territories

The urbanized environment is a complex heterogeneous system that is constantly changing. In large cities, there is a complex stress effect on living organisms. Different areas of the city may be permanently or temporarily dominated by a certain stress factor. Vegetation is a component of urban landscapes, which are natural and artificial objects of various functional purposes. The ecological functions of green spaces include: environmental protection, environmental regulation and aesthetic functions. All these functions play an important role within residential buildings, especially in children's playgrounds. Various types of damage to green spaces negatively affect their main functions. The susceptibility to damage of woody plants by insects depends on anthropogenic factors of the environment, which lead to the weakening of plants and to the loss of resistance to these types of negative influences. The resistance of plants to diseases often decreases under the influence of transport and industrial pollution in the external environment. The purpose of the study is phytopathological analysis of the green areas state on children's playgrounds in Kharkiv. Green plantations state assessment methods of urban areas using various technical means are analyzed. green plantings condition and morbidity analysis using one of the offered methods is carried out. According to the results of phytopathological analysis, it was determined that 100 % of the species Aesculus hippocastanum L., which grow on playgrounds in Kharkiv, are affected by Cameraria ohridella. Among the bushes, Syringa vulgaris L. and Spiraea L. are the most affected by diseases and pests

Meteorological conditions have a complex effect on the tree-ring width of horse chestnut Aesculus hippocastanum in a forest plantation in Latvia

The introduction of species is a tool of climate-smart management to reduce environmental risks on forest productivity, which, however, requires information regarding the climatic sensitivity of trees. The main advantages of successful introductions are improved productivity and low susceptibility to pests and diseases. The latter, however, can be compromised by the cointroduction of pests, which, however, can be delayed. In this regard, horse chestnut (Aesculus hippocastanum L.), which has been mostly used in parks and greeneries, yet has some forestry potential and has encountered an outbreak of leaf miner moth (Cameraria ohridella Deschka & Dimić), might be considered as a model species. In this study, the sensitivity of radial increment of horse chestnut growing in an experimental forest stand in Latvia and the effect of leaf miner moth on it were assessed by classical dendrochronological techniques and multiple regression analysis. In total, the time series of the tree-ring width of 27 trees were measured and successfully cross-dated. During the common period of 1978–2019, radial increment showed intermediate sensitivity, yet the dataset was representative of environmental signals with trees generally showing similar patterns of variation. Although the studied horse chestnut was growing under a cold climate (compared to native), the complex effects of summer moisture availability and winter thermal regime were estimated. Furthermore, meteorological conditions had direct and carry-over effects on increment. In general, studied trees favoured warm and moist summers and warm winters. Surprisingly, the emergence of the leaf miner moth had only some effect on the sensitivity of tree-ring width, particularly regarding temperature in May. The estimated weather-growth relationships suggest that increment might favour warming, although the emergence of the pest increases the complexity of the relationships.

The Secondary Metabolites Profile in Horse Chestnut Leaves Infested with Horse-Chestnut Leaf Miner.

Natural defensive substances synthesized by plants that could replace synthetic pesticides in the protection of plants against insect invasions are constantly being sought. The study assessed changes in the qualitative and quantitative composition of secondary metabolites in horse chestnut leaves collected in different locations and differing in the sensitivity of the plant to the invasion by the horse-chestnut leaf miner. An attempt was made to identify compounds that are most responsible for the increased plant resistance to this threat. Additionally, changes in the anatomy of chestnut leaves affected by the pest were presented. It was noticed that the trees differed in the composition of secondary metabolites already in the initial growing season, which should be related to the influence of habitat conditions. The analysis of the profile of the compounds in non-infested and infested horse chestnut leaves revealed a clear response of the plant to the stress factor, i.e., the foraging of the horse-chestnut leaf miner. Catechins seem to be compounds involved in plant resistance. The leaf anatomy showed enhanced accumulation of phenolic compounds at the pest foraging sites. Hypertrophy and thickened and cracked cell walls of the spongy parenchyma were visible in the vicinity of the mines.

The Impact of Cameraria ohridella (Lepidoptera, Gracillariidae) on the State of Aesculus hippocastanum Photosynthetic Apparatus in the Urban Environment

The paper presents the results on resistance of Aesculus hippocastanum Linnaeus, 1753 trees to Cameraria ohridella Deschka & Dimić, 1986 (Lepidoptera, Gracillariidae) impact under conditions of a modern urban environment on the example of Dnipro city as the largest industrial city in Ukraine. Field experiments were conducted in all park areas of the city, which allowed covering the full gradient of the existing urban environment and considered the different degrees of the tree settlement by the invasive insect species. The research of the impact of C. ohridella caterpillars’ vital activity on the photosynthetic apparatus state was carried out by applying a chlorophyll fluorescence induction technique. Diagnosis of photosynthetic dysfunction of fresh Ae. hippocastanum leaves was conducted using a portable “Floratest” fluorometer manufactured in Ukraine. Interpretation of the obtained Kautsky curves showed that significant changes in their critical parameters associated with the degree of leaf damage by C. ohridella caterpillars were not detected. The influence of tree growth site conditions on the following 4 main indicators of chlorophyll fluorescence induction was established: the initial value of fluorescence induction after irradiation; the value of “plateau” fluorescence induction; the maximum value of fluorescence induction; the stationary value of fluorescence induction after light adaptation of the plant leaf. It was found that the efficiency coefficients of photochemical processes in Ae. hippocastanum trees growing in low terrain levels differed significantly, which can probably be interpreted as their response to the specific characteristics of the urban environment.

Changes in the Parasitism Rate and Parasitoid Community Structure of the Horse Chestnut Leafminer, Cameraria ohridella (Lepidoptera: Gracillariidae), in the Czech Republic

The horse chestnut leafminer, Cameraria ohridella, Deschka and Dimić, is a moth that has invaded most of Europe since it was first recorded in Macedonia near Lake Ohrid in 1985. It attacks horse chestnut trees and causes aesthetic and vitality problems. The parasitism rate, other mortality rates, and parasitoid structure were studied during a five-year survey at six sites in the Czech Republic. The results showed that the total parasitism rates varied from 1.9% to 20.5%, with an average of 7.2%, similar to other those published studies. The parasitism rate was significantly related to year, the developmental stage of C. ohridella, latitude, and greenery maintenance but not to C. ohridella population density, altitude, or area size. In contrast, the total other mortality rates varied from 13.7% to 59.5%, with an average of 31%, but overall temporal changes in the values indicated a declining trend. The parasitoid complex was predominantly polyphagous parasitoids of the family Eulophidae, similar to that found previously in south-eastern Europe. The results further revealed that the most abundant parasitoid species, Minotetrastichus frontalis (Nees), was gradually replaced by Pediobius saulius (Walker). The increasing abundance of P. saulius is thus an interesting adaptation of an autochthonous parasitoid to a new host.