Pine Processionary Research Articles

Testing early detection of pine processionary moth Thaumetopoea pityocampa nests using UAV-based methods

Early detection of insect infestation is a key to the adoption of control measures appropriated to each local condition. The use of remote sensing was recommended for a quick scanning of large areas, although it does not work well with signals bearing low intensity or items that are difficult to detect. Unmanned Aerial Vehicle (UAV, or drone) may help in getting closer to individual trees and detect atypical signals of small dimensions. The larvae of the pine processionary moth (PPM, Thaumetopoea pityocampa (Denis & Schiffermüller, 1775, Lepidoptera, Notodontidae) build conspicuous silk nests on the external parts of the host plants at the beginning of the winter and their early detection may prompt managers to adopt management techniques. This work aims at testing two deep learning methods (Region-based Convolutional Neural Network - R-CNN and You Only Look Once - YOLO) to detect the nests under three different conditions of host plant species and forest stands in southern Europe. YOLO algorithm provided better results and it allowed us to achieve F1-scores as high as 0.826 and 0.696 for the detection of presence / absence and the individual nests, respectively. The detection of all the nests that can be present on a tree is not achievable with either UAV scanning or traditional ground observation, therefore the integration of the methods may allow the complete efficiency of the surveillance. The use of UAV combined with Artificial Intelligence (AI) image analysis is recommended for further use in forest and urban settings for the detection of the PPM nests. The recommended methods can be extended to other pest systems, especially when specific symptoms can be associated with an insect pest species.

Ecological characteristics of pine processionary moth Thaumetopoea pityocampa (Lepidoptera: Notodontidae) larval nests in pine and cedar forests of Algeria

Abstract. Bouzar-Essaidi K, Rahim N, Meftahi B, Benfekih L. 2023. Ecological characteristics of pine processionary moth Thaumetopoea pityocampa (Lepidoptera: Notodontidae) larval nests in pine and cedar forests of Algeria. Biodiversitas 24: 2107-2113. The pine processionary moth Thaumetopoea pityocampa) (Lepidoptera: Notodontidae) is one of the most serious pests of pine and cedar forests in Southern Europe and North Africa. In northern Algeria, outbreaks occur in the Aleppo pine (Pinus halepensis) forest, particularly in the semi-arid area and in the Atlas cedar forest (Cedrus atlantica) in the sub-humid elevation area. Under temperate and mountainous climates, the gregarious larvae of this winter-developing insect progressively build a large white, silky nest as a protective shelter during the winter period. We investigated the presence of nests and the environmental parameters (altitude, exposition) and their role in affecting the T. pityocampa density. Studies on nests of the pine processionary caterpillar were carried out in 2022 in two forest sites, namely Ghilas and El-Mroudj (NW Algeria). The mean (±SD) density of winter nests was higher in the cedar forest of El-Mroudj (1.22±0.26) than the Aleppo pine forest of Ghilas (1.62±0.60). The nest density differed with topographic orientation (F: 96.66, p<0.001). The nests of T. pityocampa caterpillars were directed mostly in the south side (the sunny part) of host trees, accounting for 48.5% and 43.5% of the total number of nests in El-Mroudj and Ghilas, respectively. At both sites, larval nest height was positively correlated with tree height (n = 126, P<0.001).

Basic Larval Structural Composition of Thaumetopoea Pityocampa (Denis & Schiffermüller, 1775) (Lepidoptera:Notodontidae ) During Feeding Inhibition Due to Some Natural Chemicals

Thaumetopoea pityocampa (Denis & Schiffermüller, 1775) (Lepidoptera:Notodontidae ) is the most important defoliating insect for several pine species and cedars. In this study, body nutrient composition of T. pityocampa larvae were analyzed under feeding inhibition caused by natural chemical agents. In no-choice assays, larvae were fed ponderosa pine needles treated with oleic acid and chlorogenic acid solutions, respectively, at each of four concentrations, 0%, 25%, 50% and 75%. The neetles were as given to separate test groups. At the end of feeding experiments, antifeedant index (AFI) was calculated for each solutions with different concentrations. Then, rates of protein, lipid, glycogen and water of larvae were calculated for control and test groups. It was determined that there had been a strong relation between concentrations of solution and AFI values regarding oleic acid (r= 0.998, P < 0.05). However, there was no significant relationship between concentrations of solution and AFI values regarding chlorogenic acid (r= 0.663, P > 0.5). The most remarkable finding was a sharp decline in the level of larval glycogen during starvation period in accordance with rising concentrations of both oleic and chlorogenic acid in its food. The glycogen level of the larvae was also affected by both chemical applications

Efficacy of Beauveria bassiana and Metarhizium brunneum isolates against the pine processionary moth, Thaumetopoea wilkinsoni Tams, 1926 (Lepidoptera: Notodontidae)

BackgroundThe pine processionary moth Thaumetopoea wilkinsoni Tams, 1926 (Lepidoptera: Notodontidae), causes severe skin reactions to animals and humans. The insect also destroys pine ecosystems by feeding on pine leaves at its larval stage. Instead of chemical control, eco-friendly biological control methods should be preferred to combat this species.ResultsThe purpose of this study was to evaluate the efficacy of Beauveria bassiana isolate (GOPT-331) and Metarhizium brunneum isolates (ORP-13 and ORP-18) against the second and fourth larval instars of T. wilkinsoni under laboratory conditions. T. wilkinsoni eggs were collected from pine trees at Ondokuz Mayıs University in Samsun, Turkey, in 2021, and the second and fourth larval instars were used for the experiment. Two milliliters of a spray of the three fungal isolates was applied to the larvae for each concentration (1 × 105–1 × 108 conidia ml−1). The mortality rates of GOPT-331, ORP-13, and ORP-18 were changed between 91.1 and 100% for the second-instar larvae and between 86.6 and 97.7% for the fourth-instar larvae at 1 × 108 conidia ml−1. The ORP-13 isolate showed the lowest LC50 values.ConclusionIn conclusion, it is suggested that all the three isolates were virulent to T. wilkinsoni and can be used for biological control of this species. The promising results from the study were obtained from trials conducted under controlled laboratory conditions, and it will be critical to explore the potential of these promising entomopathogenic fungi in field conditions.

Occupational Exposure of Forest Workers to the Urticating Setae of the Pine Processionary Moth Thaumetopoea pityocampa.

The larvae of the pine processionary moth are a threat to public health because they produce detachable setae that are about 200 µm long and 6 µm wide, reaching a total number of up to 1 million per mature individual. The setae are intended to be released to protect the larvae from predators but become a public health issue when in contact with humans and warm-blooded animals. Symptoms associated with the setae are typically urticaria and local swelling erythema, although edema of the skin, conjunctivitis or respiratory mucosa may occur. Occupational exposure concerns mainly forest workers but also farmers and gardeners. In the present study, we quantify the exposure to the setae of forest workers in a district of Northern Italy. The pine processionary moth represents a real case of occupational exposure as the urticating setae produced by the larvae caused symptoms in most forest workers directly in contact with the infested trees. In addition, the urticating setae were detected on the body of the chainsaw operators and in the surroundings of the felled trees during the operations. The non-exposed workers of the same agency did not report symptoms, with only one exception, likely linked to a non-occupational exposure. As the risk is not immediately perceived by the workers because direct contact with the larvae is unlikely, a campaign of information to workers and the general population living nearby infested forestry areas about the risk associated with airborne exposure is recommended. This becomes especially important in the areas of recent expansion of the insect, where people are inexperienced.

A review of Trichogramma Westwood parasitoids on eggs of Thaumetopoea pityocampa (Denis & Schiffermüller) in habitats of the Balkan Peninsula and Asia Minor

Studies on egg parasitoids of the pine processionary moth (Thaumetopoea pityocampa) were conducted during the period 1991-2018 in native localities of the pest on the Balkan Peninsula and in Asia Minor. In Bulgaria the biological material (2510 egg batches and 579273 eggs) was collected in 48 host localities. A number of 650 egg batches and 135611 eggs were studied from the Balkan countries (North Macedonia, Bosnia and Herzegovina, Albania and Greece), and in the Asian part of Turkey (Asia Minor), the biological material was examined from nine habitats. Eight species of egg parasitoids (Ooencyrtus pityocampae, Baryscapus servadeii, B. transversalis, Pediobius bruchicida, Anastatus bifasciatus, Eupelmus vesicularis, E. vladimiri and Trichogramma sp.) were found. The total regulating effect of egg parasitoids in Bulgaria was on average 17.6%, and in the other Balkan countries – 24.9%. Trichogramma sp. was found in 63.1% of the analysed samples in Bulgaria and in 55.6% from the neighboring countries. The percent of parasitism of T. pityocampa eggs by Trichogramma sp. was low - on average 0.39% for Bulgaria and 0.73% for the other Balkan countries. The relative share of the species in the total percentage of parasitised eggs for Bulgaria and the other countries was 2.2% and 2.9%, respectively.  

First penetration of pine processionary moth (Thaumetopoea pityocampa) in North Bulgaria

The pine processionary moth (Thaumetopoea pityocampa) was reported for the first time in North Bul-garia in 2022. Winter nests of the pest were observed in a number of pine plantations in more than 10 sites of four Forest State Enterprises (Troyan, Sevlievo, Gabrovo, Plachkovtsi). The penetration of the pest into the new localities is due to a long-distance dispersion by vehicles. In January 2023, the nests in new localities contained fifth-instar larvae of T. pityocampa. Only about 3% of them were empty as larvae had descended in the soil for pupation. Based on the high population density and presence of old nests in some localities, it was assumed that the pest penetrated into Northern Bulgaria most likely 3-4 years ago. 

First Record of Beauveria varroae, Cordyceps blackwelliae, and Purpureocillium lavendulum from Greece and Their Pathogenicity against Thaumetopoea pityocampa

Entomopathogenic fungi (EPF) consist of a wide range of fungi that can be used as pest control agents, endophytes, and plant growth promoters. In this study of EPF in suburban soils from Achaia, Greece, we used adult beetles as baits for trapping fungal isolates. According to the macroscopic and microscopic traits of the collected isolates, three species corresponded to Beauveria varroae Vuill. (Hypocreales: Cordycipitaceae); Purpureocillium lavendulum Perdomo, Gené, Cano & Guarro (Hypocreales: Ophiocordycipitaceae); and Cordyceps blackwelliae Mongkolsamrit, Noisripoom, Thanakitpipattana, Spatafora & Luangsaard (Hypocreales: Claviceptaceae). Their taxonomic identity was established by ITS-rDNA sequence amplification and sequencing, molecular database comparisons, and phylogenetic analysis. The application of these new EPF species clearly demonstrated remarkable insecticidal action on Thaumetopoea pityocampa (Lepidoptera, Notodontidae) larvae, which increased with the application dose. Our findings are important based on the enhancement of the application of new EPF species as biocontrol agents within the framework of eco-friendly pest management.

Stuck in the Caterpillars’ Web: A Half-Century of Biocontrol Research and Application on Gregarious Lepidopteran Pests in Europe

Unraveling multiple layers of collective behavior outside the well-known isopteran and hymenopteran societies was a tall order for the scientific community, especially in the case of gregarious juveniles in the order Lepidoptera. Often protected with a solid silk shelter, devoid of reproductive division of labor or conventional forms of parental care, caterpillar aggregations have rarely been considered in terms of economic importance. Of over 60 European communal species, 24 can be associated with voracious feeding habits, and thus be irruptive or pestilential, depending on the extent and severity. This review retrieves 59 cases of biocontrol against Hyphantria cunea (Drury), Euproctis chrysorrhoea (L.), Malacosoma neustria (L.), Thaumetopoea pityocampa (Denis and Schiffermüller), T. processionea (L.) and Yponomeuta malinellus (Zeller) and classifies them in predefined research and application subcategories. The percentage-wise distribution of the utilized or explored biocontrol agents was projected at 35.59% in favor of parasitoids and predators. Falling between fundamental and applicative disciplines, biocontrol, especially in its early days, built a global reputation of being underreported. To provide guidance for future research regarding the group, the functional trait-based concept used in this study is complemented with preliminary outcome assessment.

Prevalence and Distribution of Pine Processionary Moth (Thaumetopoea pityocampa) in Shahat’s Aleppo Pine (Pinus halepensis) Plantations, Al-JabalAl-Akhdar, Libya

The current study aims at investigating the spatial distribution of pine processionary moth (PPM) in parts of Al-Jabal Al-Akhdar region in Libya (in Shahat area). Two Pinus halepensis stands in the area (in Al-Mansurra and the ancient city of Cyrene) were chosen for field data collection. Growth parameters for pine trees including; tree height, crown height, diameter at breast height, stand density level, location within the stand, health condition, in addition to the observed number of PPM nests per tree were recorded. Pearson correlation coefficient analysis and variance analysis were applied to assess the relationship between obtained variables, and evaluate growth conditions for both stands. Results revealed relatively better growth conditions at Al-Mansurra site compared to Cyrene site. Moreover, PPM nests occurrence was positively correlated with trees growing isolated or on the stand edge (r = 0.54, P value <.001), and negatively correlated with tree height (r = - 0.4, P value <.001) emphasizing more dispersal rate among young pine trees. Crown height, dbh, and tree’s health condition showed no significant effect on PPM spread in the area. In-depth investigations of the population dynamics of PPM are highly recommended to provide insights into their spatial distribution in the region.

Variables Affecting the Pine Processionary Moth Flight: A Survey in the North-Western Italian Alps

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.

Factors affecting pine processionary moth (Thaumetopoea pityocampa) incidence in Mediterranean pine stands: A multiscale approach

The occurrence of the pine processionary moth (Thaumetopoea pityocampa, hereafter PPM) in Mediterranean pine forests and plantations is of increasing concern as processes such as global warming and forest cover expansion have amplified the frequency and virulence of outbreaks. This study attempts to provide as complete an overview as possible of the different factors involved in pine forest susceptibility to PPM in 98 pine stands in Central Spain. A large study area (∼3,000 km2) was considered, including three different spatial scales (<1 ha, 1 ha, 10 ha) and four different pine tree species (Pinus pinaster, P. nigra, P. sylvestris, P. pinea), monitored over a 4-year period. Models were fitted for each of the three spatial scales, as well as for a combination of them (multiscale model). Pine species had a strong influence on vulnerability to PPM, with higher incidences in stands dominated by P. pinaster and P. nigra and lower for those dominated by P. sylvestris and P. pinea. Grazing pressure, a factor thus far disregarded, was also determining, with a prominent role at both the multiscale and the stand-scale levels. Other variables were highly influential at some of the spatial scales, showing a greater resistance in pine forests or plantations with a higher diversity of pine sizes, greater tree density, and a larger cover of non-host tree species. Open habitats also played a role in PPM incidence: we detected that, both at the locality and the plot scale, the presence of clearings occupied by bushes or rocky outcrops reduced vulnerability to PPM, while the clearings with a more simplified structure produced the opposite effect. We conclude that PPM incidence is greater in structurally simple pine forests, with strong grazing pressure and abundant open spaces without woody vegetation that may favour PPM pupation. To reduce damage by PPM, pine forest and plantations should be managed to avoid oversimplified forest structures. Patches of non-host tree species should be promoted, as well as some presence of shrubs in open areas. This implies avoiding overgrazing and other management models leading to an excessive increase in bare soil. Nevertheless, it should be noted that the implementation of these recommendations should consider the remaining challenges that need to be addressed in the current context of global change, such as the increased risk of wildfires and the emergence of other pests and diseases.

Biodegradation of Pine Processionary Caterpillar Silk Is Mediated by Elastase- and Subtilisin-like Proteases

Pine processionary caterpillar nests are made from raw silk. Fibroin protein is the main component of silk which, in the case of pine processionary caterpillar, has some unusual properties such as a higher resistance to chemical hydrolysis. Isolation of microorganisms naturally present in silk nests led to identification of Bacillus licheniformis and Pseudomonas aeruginosa strains that in a defined minimal medium were able to carry out extensive silk biodegradation. A LasB elastase-like protein from P. aeruginosa was shown to be involved in silk biodegradation. A recombinant form of this protein expressed in Escherichia coli and purified by affinity chromatography was able to efficiently degrade silk in an in vitro assay. However, silk biodegradation by B. licheniformis strain was mediated by a SubC subtilisin-like protease. Homologous expression of a subtilisin Carlsberg encoding gene (subC) allowed faster degradation compared to the biodegradation kinetics of a wildtype B. licheniformis strain. This work led to the identification of new enzymes involved in biodegradation of silk materials, a finding which could lead to possible applications for controlling this pest and perhaps have importance from sanitary and biotechnological points of view.

Aggregative oviposition varies with density in processionary moths—Implications for insect outbreak propensity

AbstractIn gregarious insects, groups commonly originate from females laying eggs in masses and feeding groups are established as soon as larvae hatch. Some group‐living insect species may aggregate beyond the individual parent level, such that offspring from two or more egg masses develop within a common resource.Here we show that aggregative oviposition can vary with population density at oviposition and possibly be an important factor in outbreak dynamics of phytophagous insects.We analysed density data with respect to egg mass aggregation for two species of pine processionary moths,Thaumetopoea pinivora(in Sweden 2005–2019) andT. pityocampa(in Spain 1973–1991). Both species lay their eggs in egg masses and feed in groups. During the study periods, insect population density for both species varied by at least an order of magnitude.The two species showed strikingly similar patterns of egg mass aggregation. Egg masses were overdispersed at high population density, with few trees showing a high load of egg masses.Our data suggest that aggregative oviposition can be important in explaining the previously documented higher propensity for outbreaks in insects laying eggs in clusters, compared with those laying individual eggs.

Interactive effects of abiotic factors and biotic agents on Scots pine dieback: A multivariate modeling approach in southeast France

Forest dieback is a high risk factor for the sustainability of these ecosystems in the climate change context. Productivity losses and increased defoliation and mortality rates have already been recorded for many tree species worldwide. However, dieback is a process that depends on complex interactions between many biotic and environmental factors acting at different scales, and is thus difficult to address and predict.Our aim was to build tree- and stand-level foliar deficit models integrating biotic and abiotic factors for Scots pine (Pinus sylvestris), a species particularly threatened in Europe, and especially in the southeastern part of France. To this end, we quantified foliar deficit in 1740 trees from 87 plots distributed along an environmental gradient. We also measured tree annual radial growth and the abundance of two parasites: the pine processionary moth (Thaumetopoea pityocampa Den. & Schiff.) and mistletoe (Viscum album L.). Topographic, soil, climate and water balance indices were assessed for each plot, together with the stand dendrometric characteristics. Given the large number of environmental factors and the strong correlations between many of them, models were developed using a partial least squares (PLS) regression approach.All the models pointed to a preponderance of the biotic factors (processionary moth and mistletoe) in explaining the intensity of foliar deficit at both tree- and stand- levels. We also show that strong interactions between climate, soil, water balance and biotic factors help to explain the intensity of dieback. Dieback was thus greater in the driest topoedaphic and climatic conditions where the mistletoe and processionary moth were present.This study highlights the need to account for a wide range of biotic and abiotic factors to explain the complex process of forest dieback, and especially the environmental variables that contribute to the water balance on the local scale. The phenomenological modeling approach presented here can be used in other regions and for other species, after a re-calibration and some adaptations to local constraints considering the limited distribution area of some biotic agents.

A Selection of Experiments for Understanding the Strengths of Time Series SAR Data Analysis for Finding the Drivers Causing Phenological Changes in Paphos Forest, Cyprus

Observing phenological changes are important for evaluating the natural regeneration process of forests, especially in Mediterranean areas where the regeneration of coniferous forests depends on seeds and the changes in blossoming time are influenced by climate change. The high temporal resolution of Sentinel-1 data allows the time series analysis of synthetic aperture radar (SAR) data, but it is still unknown how these data could be utilised for better understanding forest phenology and climate-related alternations. This study investigates the phenological cycle of Paphos forest, Cyprus using SAR data from 1992 to 2021, acquired by ERS-1/2, Envisat and Sentinel-1. An average phenological diagram was created for each space mission and a more detailed analysis was performed from October 2014 to November 2021, using the higher temporal resolution of Sentinel-1 data. Meteorological data were used to better understand the drivers of blooming alternations. Using the interquartile range (IQR), outliers were detected and replaced using the Kalman filter imputation. Forecasting trend lines were used to estimate the amplitude of the summer peaks and the annual mean. The observation of the average phenology from each satellite mission showed that there were two main blooming peaks each year: the winter and the summer peak. We argue that the winter peak relates to increased foliage, water content and/or increased soil moisture. The winter peak was followed by a fall in February reaching the lower point around March, due to the act of pine processionary (Thaumetopoea pityocampa). The summer peak should relate to the annual regeneration of needles and the drop of the old ones. A delay in the summer peak—in August 2018—was associated with increased high temperatures in May 2018. Simultaneously, the appearance of one peak instead of two in the σVH time series during the period November 2014–October 2015 may be linked to a reduced act of the pine processionary associated with low November temperatures. Furthermore, there was an outlier in February 2016 with very low backscattering coefficients and it was associated with a drought year. Finally, predicting the amplitude of July 2020 returned high relevant Root Mean Square Error (rRMSE). Seven years of time series data are limiting for predicting using trend lines and many parameters need to be taken into consideration, including the increased rainfall between November 2018 and March 2020.

A glance at mathematical modeling from an ecological perspective: the problem of “Pine Processionary Caterpillar Invasion”

The purpose of this paper is to integrate mathematical modeling and ecology by presenting an activity involving an authentic environmental problem, which is called “Pine Processionary Caterpillars Invasion.” Adopting Mathematical Modeling and Education for Climate Action (EfCA) approaches, it was aimed to encourage pre-service teachers (PSTs) to use the power of mathematical modeling processes to make inferences from data and evidence and make informed decisions by producing action plans to solve an ecological problem caused by climate change. The study was conducted with eight pre-service mathematics teachers and eight pre-service science teachers in a public university in Turkey. All PSTs worked as groups so that their mastery and thinking styles enriched each other. At the end of the activity, we noticed that some of the pre-service teachers confronted difficulties such as coming up with a working mathematical model, collecting real-world data from the pine forests, and efficiently computing steps of mathematical modeling without any errors. However, pre-service teachers could make use of the views of their working partners having different disciplines and appreciated the usefulness of mathematical modeling to solve an ecological problem. They also realized the interconnectedness of species and developed empathy for the welfare of society and nature.

Efficacy of Diptera-targeted Bacillus thuringiensis var. israelensis against the pine processionary moth, Thaumetopoea wilkinsoni (Lepidoptera: Notodontidae)

The pine processionary moth Thaumetopoea wilkinsoni (Tams, 1926) (Lepidoptera: Notodontidae) is one of the most harmful species that destroys to the pine ecosystem and causes severe skin reactions in humans and animals due to its urticating setae. The aim of this study is to evaluate the efficacy of the hypertoxic strain of Diptera-targeted Bacillus thuringiensis var. israelensis against the second instar larvae of T. wilkinsoni under laboratory conditions. A total of 5 mL of bacterial strain spray was applied to 30 larvae at concentrations of 101, 103, 105, 107, and 109 cfu/mL. As a result of the study, it was determined that the survival rate of the larvae exposed to Bti pHTppk decreased with increasing bacterial concentration, and the survival rate of the 109 cfu/mL concentration group was 33.3%. It is suggested that Bti pHTppk is virulent for T. wilkinsoni larvae and that this strain can be used in the biological control of this species.

Even the current climate change winners could end up being losers

A recommendation of: Asma Bourougaaoui, Christelle Robinet, Mohamed Lahbib Ben Jamâa, Mathieu Laparie Effects of climate warming on the pine processionary moth at the southern edge of its range: a retrospective analysis on egg survival in Tunisia https://doi.org/10.1101/2021.08.17.456665

Application of Remote Sensing Data for Assessment of Bark Beetle Attacks in Pine Plantations in Kirkovo Region, the Eastern Rhodopes

Intensive forest afforestation with native pine species was developed in the 1960s on degraded and deforested lands in the region of the Eastern Rhodopes (south-eastern Bulgaria). Severe damage by wet snow was registered in the coniferous forests of the Rhodopes in March 2015. In the following years, bark beetle attacks were registered on the broken and felled fresh wood. As a result, bark beetle infestation spots appeared in the pine plantations. In the period 2019–2021, damage caused by bark beetles was assessed in the region of State Forestry Kirkovo (the Eastern Rhodopes, south-eastern Bulgaria). An integrated approach using the data of the information system of the Executive Forest Agency (ISEFA), remote sensing data obtained by an “eBee SQ” unmanned aerial vehicle (UAV) equipped with a “Parrot Sequoia” multispectral camera, and subsequent terrestrial observations, was applied. ISEFA data showed that there was no serious damage caused by abiotic and biotic factors in the pine forests of SF Kirkovo until 2014. Snow damage in 2015 affected 513 ha of pine plantations, and bark beetle infestations reached up to 1316 ha in 2016. In 2019, a total of 226.87 ha of pine plantations were captured in three localities—Fotinovo, Kirkovo, and Kremen. The relative share of damage caused by bark beetles was greater in P. sylvestris plantations (15.3–23.0%), compared to damage in P. nigra (2.3%). Four different categories of normalised difference vegetation index (NDVI) were separated in bark beetle infestation spots—living trees, dead trees, grass and shrub vegetation, stones and rocks. The NDVI values in locations with living trees varied between 0.500 (spaces between tree crowns) and 0.700 (central part of the crown projection) (an average of 0.617). In the locations with dead trees, the average values of NDVI of lying trees was 0.273, and in standing trees, NDVI varied between 0.275 (central part of crown projections) and 0.424 (spaces between tree crowns). In the locations with grass and shrub vegetation, stones and rocks, the average NDVI was 0.436 and 0.329, respectively. In the field study, average defoliation of 31.2–32.3% was registered in P. sylvestris plantations, and 47.4% in P. nigra plantations. Defoliations mainly were caused by pine processionary moth (Thaumetopoea pityocampa) and fungal pathogens (Dothistroma septosporum and Lecanosticta acicola). The damage was caused by Ips acuminatus (in P. sylvestris only), and I. sexdentatus, Tomicus piniperda and T. minor (in P. sylvestris and P. nigra). Infestations by other xylophages, such as Phaenops cyanea, Rhagium inquisitor, and Pissodes spp., were also found on pine stems.