Optimization of the environment by forest-reclamation arrangement entails a transformation of aboriginal communities of flora and fauna. In recent years, an increase in the quantitative abundance of gall-forming arthropods has been observed in the protective forest stands of the Volgograd Region. This gives a reason to expect further increase in the diversity and harmfulness of gall-forming arthropods in the area. For the first time, studies of the complex of gall-forming insects were carried out in the protective forest strips of the arid zone of the Lower Volga region. The largest number of insect species forming galls (25 species) is recorded in the oak crowns. Among them, Cynipoidea predominate (56.0% of the total number of species of gall-forming oak insects). Every year representatives of Cynipidae (Hymenoptera) are found in large numbers: Cynips quercusfolii (Linnaeus, 1758), Neuroterus albipes (Schenck, 1863), N. anthracinus (Curtis, 1838), N. numismalis (Fourcroy, 1785), N. quercusbaccarum (Linnaeus, 1758), etc. The complex of elm gall-forming insects includes 11 species, and in the crowns of these trees gall aphids are more diverse (44%, respectively). The permanent inhabitants of the foliage are: Colopha compressa (Koch, 1856) (Hemiptera, Pemphigidae), Eriosoma lanuginosum (Hartig, 1839), E. ulmi (Linnaeus, 1758) (Hemiptera, Aphididae), Janetiella lemeei (Kieffer, 1904), and Physemocecis ulmi (Kieffer, 1909) (Diptera, Cecidomyiidae). The taxonomic diversity of aphids in the protective forest plantings hover around 24.4% of the total diversity of these pests. The quantitative characteristics of gall-forming agents vary widely across biotopes. Based on the field data, we calculated and analyzed the information characteristics of gall-forming communities trophically related to the main forest-forming species (Ulmus and Quercus). The variability of entropy characteristics will allow to determine the adaptive capabilities of a group of gall-forming insects and predict the dynamics of pest development in plantings of different species composition and design parameters. In the presence of a wide variability in the abundance of galls, the trend of dependence on the number of breeds, the share of the main breed and the row (width) of the forest strip is clearly expressed.

Spruce bud scale Physokermes piceae (Schrank, 1801) is a dangerous pest of natural spruce forests and man-made amenity plantations. In the steppe zone of Ukraine spruce is represented exclusively by introduced species, therefore this bud scale has the status of an invader. From its initial invasion in 1983 until 2020, four increases in abundance of spruce bud scale lasting for 2–3 years have been observed. Despite this, there were no previous studies focused on the biology of this pest in the steppe zone of Ukraine. This work is based on the materials collected in 2018–2020 in 17 model areas of city green spaces in Donbass, located within the steppe zone of Ukraine. The study focused on the number of species of the genus Physokermes in the region, their phenology, trophic preferences, distribution pattern in the food plant crown, and the spread throughout urban plantations. In the researched area the genus Physokermes is represented by one species, namely P. piceae. Biological characteristics of the spruce bud scale in the Ukraine’s steppe is only insignificantly different from the data reported for the forest and forest-steppe zones. This fact is indicative of the naturalization of this phytophagous insect in the researched area. However, a number of differences were noted in the distribution of the spruce bud scale along the host plant. Showing no confinement to the crown layers and expositions, the studied bud scale goes deep into the crown and undergoes transition to feeding on a 3-, 4-, and 5-year growth, which is probably associated with high summer temperatures and low air humidity. In the collection of the Donetsk Botanical Garden, P. piceae damaged Picea abies (L.) H. Karst., P. obovata Ledeb., P. orientalis (L.) Peterm., and P. pungens Engelm with varying intensity. The study has identified a group of unsusceptible species, namely Picea asperata Mast., P. engelmannii Parry ex Engelm., P. koraiensis Nakai., and P. omorika (Pancic) Purk. In Donbass, P. piceae is found in all types of the city green plantings with spruce. Despite the phytophagous insect's population density, we observed no overall decay and loss of ornamental characteristics in spruce in green spaces of the steppe zone of Ukraine.

The paper considers approaches to the use of some additional (hidden) parameters to analyze population dynamics of forest insects. The study presents the analysis of data on the population dynamics of phyllophagous insects of Scots pine obtained during a long-term continuous monitoring (1979–2016) of five phyllophagous species on the territory of the Krasnoturansk pine forest (south of Krasnoyarsk Territory), data on abundance dynamics of insects in forest stands in Switzerland (Oberengadin valley), and data on abundance dynamics of the Siberian silkworm Dendrolimus sibsiricus Tschetv. in the taiga forests of Siberia. To analyze the features of the population dynamics we used the rank distribution of the long-term density of species in a particular habitat, the characteristics of the distribution of individuals on trees, considered from the point of view of the model of second order phase transitions, as well as the parameters of autoregressive equations for the dynamics of the population, with the account of the order of autoregression, the sign of the model coefficients, and the stability margin. It is shown that the indicators of competition between species in a community are weakly related to the changes in population density in the community, and the competition coefficient b can be considered as an independent indicator of the state of the community. The use of the hidden parameter b makes it possible to estimate the competition between species in the insect complex in the Krasnoturansk pine forest and between species in the complex of the species of insects in the larch forests of the Alps. Using a phase transition model of the second kind, it is shown that the dispersal of the species on the accounting units (trees) on the trial plot is of a group nature and, therefore, the pest has an increased effect on some trees. The possibility of using autoregressive equations to describe the dynamics of the populations of certain species is considered. It is shown, that AR-models describe well enough the dynamics of the population size in various natural boundaries. Coefficients of AR-equations and the values of the stability margin of these equations can be considered hidden parameters of dynamics. The «hidden» patterns of the population dynamics characterize the long-term dynamics of the number of forest insect communities. The long-term properties of insect populations are considered with the help of these “hidden” parameters (not directly measured). These parameters must be taken into account when assessing the type of species dynamics. With the help of “hidden” indicators, it is possible to obtain additional information about the properties and dynamics of the studied populations. 

For the first time, a review of gall midges-inquilines, developing together with gallformers, among which gall midges dominate is provided. In the world, 197 species of gall midges of 41 genera have been identified, in the galls of which 177 species of inquiline gall midges from 27 genera have been found. They are found on plants of 243 species of 160 genera of 53 families and 20 orders. The core of the gall-forming fauna is Cecidomyiinae – 118 species (59.9%) from 26 genera (63.4%), and the core of the inquiline fauna is Lasiopterinae: 63 species (32.0%) from 15 genera (36.6%). Ten common genera were identified, in which there are both inquilines and gall-formers. The proportion of inquilines in these genera is more than a third of the species, for Macrolabis – 39.1% (25 out of 64) and Camptoneuromyia – 86.7% (13 out of 15). Gallformers and inquilines are predominantly narrow oligophages, specific in respect to the genus or family of the host plant, predominantly Fabaceae. Among gall-formers, the share of specific genera is 61.0% (25 out of 41), while among inquilines is 37.0% (10 out of 27). Host plants of the Rosids subclass are represented by 124 species (51.0%), 88 genera (55.0%) from 28 families (46.2%), most of which are trees and shrubs. Inquiline gall midges have been found in all zoogeographic regions; however no common species have been found. They dominate in the Palaearctic (118 species, 66.7% of 177) and Neotropical (40 species, 22.6%) regions. In the Nearctic region there are only 15 (8.5%) species. In the Palaearctic, inquiline species have been identified in 19 genera (70.4% of 27), of which 7 are endemic. In the Neotropical region, the inquilines belong to 7 genera (25.9%), with no endemics found. The core of the fauna with an abundance of endemic and widespread genera of inquilines formed in the Palaearctic region. In the gall midges, inquiline gall midges predominate, but inquilines develop from other taxonomic groups : insects (with a predominance of Cynipidae) and fungi. Inquilines present the potential for their gradual transition to gall formation and possible speciation during the assimilation of galls and plants of other species. In the galls of gall midges, inquilines actively influence the formation of galls and the development of the host larvae, contribute to their feeding, inhibit or lead to death.

Development of the first generation of Corythucha arcuata in the climate of the foothills and lowlands of the Northwest Caucasus starts in the early May. With a natural day length and the threshold for post-diapause imago development of 11 oC, it requires 333–404 degree-days and at least 43 days. The death of the overwintered females in this zone is observed by the end of June, coinciding with the reduction of the total portion of females to 2–7%. In the highlands imagoes are dispersing in June as well, surviving until July on willows and birch trees. Peak of the first-generation imago outcome occurs at the end of June. Migration of fertilized females of the first generation to new forage plants is followed by mass egg laying (i.e. beginning of the second generation). During the formation of large nests in the foothills, the flight of bugs is observed even in treeless highlands. Development of the preadult stages of the second generation (without changing feed plants) takes place starting at mid-June. Metamorphosis requires 361–430 degree-days and takes at least 16–23 days. The peak of the emergence of the second generation imagoes at the end of July coincides with their dispersal, which is also dominated by females. The third generation develops in August. It requires 329–350 degree-days and takes 19–28 days. The peak of the emergence of the G3 imagoes falls on the first third of September. It is preceded by an earlier emergence of males, determined by their mass local and regional migrations since the end of August. The fourth generation is obligated and develops (without changing feed plants) from the end of August to the end of September. It requires at least 378 degree-days and takes at least 26 days. Late nymphs resulting from female immigrant of the third generation (on new trees) give imagoes only by mid-October. The last migration of bugs is observed in early to mid-October. Imagoes of the third and fourth generations with the predominance of females hibernate in the oak forests of the foothills and low-mountain. In the midlands they may be accompanied by the overwintering immigrants of the second generation, with the predominance of males, formed in September.

Microorganisms associated with plants, including conifers, play an important role in their life, forming microbial communities of the phyllosphere, rhizoplane, and rhizosphere. Conventionally, the composition of such complexes can be divided into pathogenic and saprotrophic parts. For specialists involved in reforestation, the knowledge of the species diversity of pathogens that cause diseases of seedlings of conifers is essential for correcting agrotechnical measures and controlling the quality of planting material. The goal of this research is to study the species diversity of pathogenic micromycetes of conifers in the Middle Siberia territory, both in artificial and natural plantings. Such long-term studies found representatives of 36 genera belonging to different taxonomic groups: Lophodermium Chevall., Lophodermella Höhn., Cyclaneusma DiCosmo, Peredo et Minte, Gremmenia Korf., Hypodermella Tubeuf, Lirula Darker, Sarea Fr., Herpotrichia Fucke, Gremmeniella M. Morelet, Coleosporium Lév., Chrysomyxa Unger, Melampsora Castagne, Melampsorella J. Schröt., Pucciniastrum G.H. Otth., Cronartium Fr., Typhula (Pers.) Fr., Mucor Fresen., Rhizosphaera L. Mangin et Har, Pestalotia De Not., Sclerophoma Höhn. (teleomorph – Sydowia Bres.), Stagonospora (Sacc.) Sacc. (= Hendersonia Berk.), Lecanosticta Syd., Dothistroma Hulbary, Meria Vuill.( teleomorph – Rhabdocline Syd.), Phoma Sacc., Didymella Sacc., Alternaria Nees, Cladosporium Link, Rhizoctonia DC., Botrytis P. Micheli ex Pers., Septorioides Quaedvl., Verkley et Crous, Epicoccum Link, Trichothecium Link., Cylindrocarpon Wollenw. (teleomorph – Neonectria Wollenw). The identified pathogens cause premature death of the assimilation apparatus, disrupt the activity of the root and vascular systems, and reduce the quality of coniferous plants seeds.

The general weakening and drying out of trees in the green stands of St. Petersburg in recent years has raised serious concerns. The majority of old-growth trees in particular has mechanical damages to the trunks and roots that are the gateways for the phytopathogen infection. The most common are wood-destroying fungi that cause stem and root rot, which leads to a decrease in the mechanical strength of wood that results in the occurrence of windblow and windbreak when the affected trees become a threat to visitors and the property. The greatest harm in stands is caused by the honey agarics, a collective fungi group belonging to agaricomycetes. The goal of the study is to examine the causes of tree damage by the honey agarics in the stands of Elagin Island, identification of the influence of the hydrological regime on the  development of the pathogen, and development of proposals for the improvement of standing timbers. To detect foci of the honey agarics and the degree of its influence on the condition of trees, exploratory and detailed surveys were carried out. Particular attention was paid to the compilation and analysis of the cartographic material on the location of the main foci of the pathogen. The occurrence of the honey agarics was recorded in the areas with different levels of ground water. It was found that development of the root rot also depends on the flooding of the trees' roots due to water regime deterioration in the soils of Elagin Island. The foci are located in the areas of excessive soil moisture and coastal zones. The reasons for the water stagnation on the island have been clarified. The proposed measures to improve the stands of the island should include not only phytosanitary measures but also efforts to improve the growing conditions of trees without changing the historical appearance of the park.

The goal of the research was to reveal the features of the spread of the emerald ash borer (EAB) in the stands of the Luhansk region during the first year after its detection. The stands with the presence of the common ash (Fraxinus excelsior) and the green ash (F. pennsylvanica) in the forest fund of Starobelskoe, Belokurakinskoe, and Svatovskoe Forest and Hunting Enterprises, located to the west of the points of the first detection of EAB in the Luhansk region, were examined. The EAB was found in almost all stands with the presence of green ash in the composition, which comprises 11.1% of the forested area. During 2020, the EAB spread over a distance of 32–52 km from the first detection point. The southernmost point where it was registered is near Melovatka, and the westernmost – is near Dontsovka. Taking into account the tendency of EAB to spread in the southwestern direction, we can expect its invasion to the Kharkiv and Donetsk regions. EAB inhabits mainly green ash, and in common ash it prefers sprouts, trees in the stands with low relative stocking density, and trees at the edges and along the perimeter of small forests or forest belts. The mean density (±S.E.) of EAB larvae in populated branches does not differ significantly for green ash and common ash (0.6±0.07 and 0.7±0.09 larvae/dm2, respectively). However, the proportion of EAB colonized branches of green ash (91.4±3.12%; n = 45) is significantly higher than that of common ash (76.1±6.29%; n = 82). The exit holes of EAB in the trees of common ash were not found. Maturation feeding of EAB was registered only in the trees of green ash. The presence of EAB galleries and larvae in the trees of the 1st and the 2nd categories of health condition (healthy-looking and weakened trees according to the Sanitary Rules in the Forests of Ukraine) indicates the aggressiveness of EAB. The dynamics of the health condition of EAB colonized trees, as well as the survival of its larvae are to be investigated further, especially for the common ash, which proportion in the stands of the region is about 36.9% of forest-covered area.

Since one of the main goals of pheromone monitoring of forest insects is monitoring of the population density of the target species, correlations between catch efficiency of pheromone traps and population density began to be analyzed immediately after their widespread use in the forest protection practice. The absolute majority of authors that carried out such analysis, noted the absence of a direct correlation between population density and the results of pheromone monitoring of the gypsy moth Lymantria dispar (L.). In the mountainous conditions of Southern Kyrgyzstan, during the many years of pheromone monitoring (2001–2007), a high catch rate of males in traps was recorded, regardless of the population density. The goal of this study was to determine the effect of the trap layout and the distance between them on the results of pheromone monitoring. Three groups of trap lines were set up with a distance of 200– 250 m between the traps in a group. The first line of traps was set up in the belt of the pistachio light forest (800–1200 m above sea level), the second line was set up in the zone of mixed stands (1200–1600 m above sea level), and the third line was set up in the walnut belt (1600–2000 m above sea level). The elevation difference between the lowest and the highest trap was more than 700 m, and the distance between these extreme traps was more than 10 km. The results of this monitoring show that with stable air flows, males in the mass can travel up to two kilometers to a point source of the pheromone. Some males can travel up to 4 km. Males are capable of traveling long way, as indicated by the appearance of males in the uppermost traps of the upper zone during the beginning of their summer flight at the lower zone. The results of this study confirm our earlier conclusion about the significant influence of stable air flows on the results of pheromone monitoring. Under these conditions the distance of 2 km or less between traps leads to significant decrease in the objectivity of monitoring results.

Developing sustainable forest management strategy targeted to preserve biodiversity and forest ecosystem functions in managed forests requires knowledge of the characteristics of coarse woody debris in primeval (reference) forests. Natural disturbances such as fires, windthrows, and insect outbreaks cause significant tree stand mortality and consequently lead to the high input of coarse woody debris (CWD) [in primeval forests]. The study was carried out in 2020 in the «Vepssky Forest» reserve, which is situated in the eastern part of Leningrad region, Russia. The data were collected from 74 permanent circular sample plots (0.1 ha each). The tree stands were variable in terms of tree age structure, species composition, site type, and stage of successional dynamics. The stocks and diversity of CWD were evaluated in primeval forest ecosystems of the «Vepssky Forest» reserve. The volume of CWD varied from 30 to 532 m3ha–1, and averaged 195 m3ha–1. The highest amounts of CWD were found in the forest stands of Myrtillosum type (mean 231 m3ha–1). Norway spruce (Picea abies) CWD in the second and third decay classes had the highest share of all CWD volume.

The optimized monitoring system of the Siberian moth Dendrolimus sibiricus Tchetverikov (Lepidoptera: Lasiocampidae) was developed during the implementation of the Forest Resources and Technologies (FOREST) international project funded by the United States Agency for International Development (USAID) in 2001–2005. It includes successive stages of forest pathology zoning of the subjects of the Russian Federation, individual forestry enterprises, organization of pheromone monitoring of sparse Siberian moth populations and, only when the population growth is recorded by the means of traps (above 100 male moths / trap / season) – transition to caterpillar sampling. In the course of the project, the technology for pheromone monitoring of the pest was developed for the first time (a pheromone analogue was synthesized, a dispenser, trap and fixing insecticidal strip were created, a methodology of accounting and a decision-making algorithm was recommended). The project financed the creation of a three-volume handbook "Diseases and Pests in Russian Forests", subsequently published by the Forestry Agency of Russian Federation. The monitoring system tested and implemented in the course of the project in the Tomsk, Irkutsk, and Sakhalin Districts, Krasnoyarsk, Khabarovsk, Primorskiy krays and the Republic of Buryatia serves as a vivid example of fruitful cooperation between scientists of the Russian Academy of Sciences and forestry universities with forestry practitioners.