Insect outbreaks are major biotic disturbances in forest ecosystems. Defoliating insects reduce leaf area, limiting photosynthetic capacity and resource availability for physiological functions and foliage regrowth. This is particularly critical in evergreen conifers that store resources in older foliage and have high leaf construction costs. Understanding structural and physiological adjustments in new foliage following defoliation is essential to assess tree resilience and ecosystem recovery. We examined the effects of pine processionary moth (PPM, Thaumetopoea pityocampa) defoliation on Pinus nigra leaf functional traits in two stands in north-central Spain. In 2023, we collected branches from a total of 38 trees with contrasting degrees of defoliation and measured needle length, width, number of stomatal rows, and stomatal density on needles formed following the defoliation event. We also recorded physiological traits, including the maximum quantum yield of PSII (Fv/Fm; July and September), stomatal conductance (gs) and net photosynthetic assimilation rate (An; September; n=18 trees). Additionally, we measured needle length, width, and Fv/Fm of needles produced prior to the defoliation event (1-year-old needles). Linear mixed models and a structural equation model were employed to analyze both direct and indirect effects of defoliation on structural traits, while general and generalized linear models were used to assess physiological changes. Defoliated trees produced longer new needles, suggesting a strategic allocation of resources toward crown recovery. Stomatal rows and density did not vary with defoliation but were instead related to needle width. Fv/Fm was unaffected by defoliation. Finally, defoliated trees showed higher An values without concomitant changes in gs, indicating a mechanism of photosynthetic upregulation that is not hydraulically mediated but might be driven by greater resource allocation. Together, these results suggest that Pinus nigra can partially compensate for canopy loss through structural and physiological adjustments, although complete defoliation may compromise tree resilience.

Phytochemical composition and larvicidal activities of Artemisia herba-alba, Thymus numidicus and Citrus limon peel essential oils on the pine processionary moth

Effects of tree size and foliage structure on egg-laying patterns of the pine processionary moth in Aleppo pine forests

The essential oils of Cupressus sempervirens L (C. sempervirens) and Mentha pulegium L(M. pulegium), rich in α-ocimene, δ-3-carene (27.43%) and pulegone (72.68%), respectively, were evaluated for their insecticidal activity against Thaumetopoea pityocampa (T. pityocampa ) (Denis and Schiffermüller, 1775). In ingestion bioassays, M. pulegium EO showed the highest efficacy, reaching 100% mortality at 150 µL/mL for L4 and L5 instars, with LC50 values of 38.835 and 33.835 µL/mL.C. sempervirens essential oil exhibited the highest toxicity against third-stage T. pityocampaSchiff larvae, with LC50 values of 13.02 µL/mL (ingestion) and 47.59 µL/mL (contact), and corrected mortality up to 100%. Fumigant bioassays confirmed complete mortality of L4 larvae at 100ul/mL (LC50 = 22.1 µL/mL). In vivo, larval survival dropped from 100% to 0% within 18 days, and biochemical analyses revealed significant depletion of lipid, carbohydrate, and protein reserves.

In this study, we investigated the potential use of housefly Musca domestica (Linnaeus, 1758) (Diptera: Muscidae) larvae as an alternative feed for mass-rearing Calosoma sycophanta (Linnaeus, 1758) (Coleoptera: Carabidae), a species utilized in biological control against forest pests. Our research focused on the egg production efficiency of Calosoma adults when fed housefly larvae and the growth and development of first-instar Calosoma larvae under laboratory conditions. We compared these groups with Calosoma individuals fed on pine processionary moth (PPM), Thaumetopoea wilkinsoni (Tams, 1926) (Lepidoptera: Thaumetopoeidae). The results indicated a significant increase in weight for first-instar C. sycophanta larvae after 16 days: a 52.9-fold increase when fed PPM and a 16-fold increase when fed housefly larvae. In terms of length growth, PPM-fed larvae demonstrated a 4.52-fold increase, whereas housefly-fed larvae showed a 3.06-fold increase. Although the larvae consumed M. domestica larvae, the adult Calosoma did not produce eggs, and the larvae did not pupate. In contrast, Calosoma adults fed with T. wilkinsoni produced eggs, with their larvae successfully maturing to adulthood. Fifty percent of larvae fed with PPM and eighty percent fed with houseflies survived to 16 days. The findings suggest that while Calosoma larvae raised on houseflies are smaller and lighter than those fed with PPM, feeding them houseflies for a minimum of two weeks and subsequently releasing them in their larval stage could aid in the biological control of PPM.

Occupational contact urticaria (OCU) is an immediate-type skin reaction triggered by chemicals or proteins encountered in the workplace. It is classified as either nonimmunologic (irritant) or immunologic (IgE-mediated), which differ in pathogenesis, diagnostic approach, and clinical severity. Immunologic OCU may present with generalized urticaria and even anaphylaxis. We conducted a systematic narrative review to provide an updated overview of OCU, integrating findings from a structured literature search (2017-2025) with expert clinical interpretation. This review synthesizes knowledge on causative agents, diagnostic strategies, and management approaches, with a focus on emerging occupational exposures. The spectrum of occupational allergens continues to expand, with new reports implicating Cannabis sativa , arthropods (e.g., Anisakis simplex , pine processionary caterpillar), mask materials such as polypropylene, disinfectants (e.g., chloramine-T), antiseptics (e.g., chlorhexidine), cosmetic ingredients (e.g., henna, indigo, and hydrolyzed wheat protein), and enzymes (e.g., alpha-amylase, cellulase, papain, protease, and xylanase). Despite novel exposures, traditional culprits like natural rubber latex, ammonium persulfate, and animal-and plant-derived foods remain prevalent. Early recognition, diagnostic testing, and prevention are essential to reduce systemic involvement and occupational disability. Strengthening workplace awareness, surveillance programs, and systematic occupational health, safety, and environmental management remains essential to reducing this preventable condition.

In Algeria, two Thaumetopoea species (Lepidoptera: Notodontidae), Thaumetopoea bonjeani (cedar processionary moth, CPM) and Thaumetopoea pityocampa (pine processionary moth, PPM), coexist in Cedrus atlantica forests causing significant tree damage and posing health risks to humans. This study investigates key bioecological differences between these species, which share similar environmental conditions, by comparing their reproductive potential, with a focus on fecundity, egg batch characteristics, and mortality factors. A total of 125 egg batches were collected from C. atlantica in two cedar forests: 75 batches of T. pityocampa were collected from Chréa forest and 50 batches of T. bonjeani from Tala-Guilef forest. The PPM showed significantly higher fecundity, with an average of 222.68 eggs per egg batch, compared with 135.84 eggs for CPM. Although mean egg batch lengths were similar (~25 mm), PPM females preferred larger branches (2–10 mm diameter) than CPM (2–7 mm). The average number of egg rows per batch was greater in PPM (10.77) than CPM (5.56). Regression analysis revealed positive correlations between egg batch length, egg count, and row number in both species, although branch diameter was significantly correlated only in CPM. Hatching rates were higher for PPM (90.6%) compared to CPM (60.4%), with predation being the primary mortality factor for CPM eggs (17.1%) compared to 1.1% in PPM. Egg parasitism also differed significantly between the species, with Ooencyrtus pityocampae dominating CPM parasitism and Baryscapus servadeii and Trichogramma sp. predominating in PPM. These findings enhance our understanding of species-specific life-history strategies and offer important implications for the development of targeted and ecologically informed pest management approaches in Mediterranean forest ecosystems.

ABSTRACTAllochronic divergence is a key evolutionary mechanism that can frequently lead to incipient speciation. Although theoretical models suggest that such divergence is notably facilitated by small population size and genetic polymorphisms influencing reproductive timing, though constrained by genetic load, empirical validation remains limited. We investigated these predictions by re‐analysing a case of allochronic differentiation between two sympatric populations of pine processionary moth (Thaumetopoea pityocampa) in Portugal, using whole genome resequencing (IndSeq and PoolSeq) of those two populations and eight allopatric ones. We inferred the demographic history of those populations, assessed their genetic load and searched for genomic regions associated with life cycle differences. Our analyses revealed a recent split between the sympatric allochronic populations, accompanied by a strong reduction in gene flow, bottlenecks, inbreeding and accumulation of deleterious variants. Genome scans identified several loci associated with life cycle variation, including genes putatively involved in circadian rhythm regulation, predominantly located on the Z chromosome. We discuss how these empirical genomic findings support theoretical expectations that assortative mating driven by differences in reproductive timing, underpinned by polymorphisms in circadian genes, along with genetic drift and purge of genetic load at high‐impact sites, can promote the onset and persistence of allochronic divergence.

This study aims to develop susceptibility maps for the Pine Processionary Moth (PPM) via multi-criteria decision-making methodologies. This study utilized data on forest stands affected by PPM damage within the Nurdağı Forest Planning Unit in Gaziantep province from 2018 to 2024. Parameters including stand structure, crown closure, development stage, elevation, slope, aspect, annual mean temperature, solar radiation, and annual mean precipitation parameters were used to create the PPM susceptibility maps according to the Analytical Hierarchy Process (AHP) and the Frequency Ratio Method (FRM). Their precision was evaluated by Relative Operating Characteristic (ROC) analysis. The AHP model indicates that 73% of the forest stands with PPM damage fall into the high and extreme susceptibility groups, whereas the FRM model shows that 68% of such forest stands are similarly categorized. The AUC values for the FRM and AHP models were determined to be 0.830 and 0.835, respectively. The results reveal that the PPM susceptibility maps generated using the AHP and FRM models are reliable.

This paper presents research conducted to determine the most important ecological conditions that influence the onset and course of the flight of male pine processionary moths (Thaumetopoea pityocampa Schiff.) in the Orjen Mountain area, which belongs to Bosnia and Herzegovina.The ecological conditions monitored in the study area were air temperature and relative humidity, which are correlated with the flight of the imago of this harmful species.The onset of adult emergence and the duration of the flight period were determined using pheromone traps with lures and by counting the captured male pine processionary moths.The research showed that higher average daily temperatures led to a much more intense male flight activity in this area.The most intense flight, with the highest number of captured adults (1,336), was recorded on August 22, i.e., during the period from July 31 to August 22, when the average daily temperature was 23 C.Based on the determined values of ecological conditions and the bionomy of the imago, the pine processionary moth population in this area is characterized as a winter population, i.e., an early type of pine processionary moth.

Induced defense in trees refers to the increased production of specific substances in response to herbivore attacks, which negatively affects the herbivore. This type of resistance can contribute to the sustainable management of herbivorous insect problems in forest ecosystems. The Aleppo pine, a drought-resistant forest tree species, holds great ecological and socioeconomic importance. One of its predators is the Pine Processionary Moth (PPM) Thaumetopoea pityocampa. This study explores the impact of new foliage that emerges following severe defoliation caused by the PPM on the subsequent year’s larval performance. Moreover, we investigate whether there is a difference in the chemical composition of the foliage of defoliated and undefoliated trees in terms of terpenes (monoterpenes, sesquiterpenes, and diterpenes), total phenols, nitrogen (N), carbon (C), and the C/N ratio. The aim is to determine whether these components act as an induced defense mechanism. The results indicate that the performance of L1 larvae was negatively affected by new foliage after defoliation. Larvae feeding on new foliage experienced high mortality rates and were significantly shorter than those that fed on the foliage of undefoliated trees. The chemical composition analysis revealed that only the new foliage after defoliation contained bornyl acetate (monoterpene), and the concentration of p-cymene (another monoterpene) was higher in this new foliage compared to that of undefoliated trees. Furthermore, two diterpenes, methyl dehydroabietate and dehydroabietal, showed a stronger correlation with defoliation. These compounds have demonstrated insecticidal activity against other insects and could potentially serve as starting components for a bio-insecticide against the PPM. These findings suggest the presence of an induced defense in Aleppo pine, as the tree produces foliage containing specific terpenes that are unfavorable to larvae. This is one of the factors contributing to the reduction of the PPM population. However, due to the current climate change situation, further research is necessary to better understand how these conditions impact the susceptibility of trees to defoliation.

Defense mechanisms were studied for Pinus brutia, a cornerstone Turkish forest tree, against pine processionary moth damage by Thaumetopoea pityocampa (Den. & Schiff.) and Thaumetopoea wilkinsoni Tams 1926 moth species. This research addressed the significance of Pinus brutia in afforestation and breeding. The expression of enzymatic antioxidants (SOD, POD, CAT, APX) and photosynthetic pigments (chlorophylls and carotenoids) at a clonal level in response to insect damage was assessed. Approximately 84 needle samples from 28 Pinus brutia clones from the Antalya Düzlerçamı Brutian Pine Seed Orchard were studied. Samples were collected in February and August 2021 to capture responses during key insect activity periods. These samples were then analyzed for pigment concentrations and antioxidant activities. Statistical analysis revealed that sampling period and clone significantly affected chlorophyll and carotenoid levels. The POD and SOD activities were primarily influenced by the sampling period. However, CAT activity was affected by the number of insect pouches, the period, and the clone. APX activity was significantly impacted by both pouch number and sampling period. These findings offer insights into how seasonal changes and genetic variations modulate P. brutia clones’ defense mechanisms against pine processionary moth infestations, informing future forest management.

Mixed forests exhibit greater resistance to pests compared to monospecific forests. However, stand-level diversification is challenging for managers. An alternative approach is to enhance tree diversity at the landscape scale. Building on the agricultural landscapes with hedgerows, we hypothesized that in a pine plantation landscape broadleaved hedgerows along pine stands locally increase tree diversity, while broadleaved stands increase landscape level diversity. According to the associational resistance concept, both methods should reduce pest damage. We tested these hypotheses in a pine plantation landscape (dominated by Pinus pinaster), by counting nests of the pine processionary moth (Thaumetopoea pityocampa, hereafter “PPM”) along 36 pine edges adjacent or not to broadleaved hedgerows, in landscapes with low or high broadleaved cover. PPM bird and bat predators activities were assessed using acoustic devices. At the local level, PPM nests were 42% less abundant in pine edges adjacent to taller hedgerows. This reduction was attributed to the ability of hedgerow to disrupt PPM host tree location and to the predation by great tit (Parus major), which was more active in pine edges adjacent to hedgerows. At the landscape level, higher broadleaved cover resulted in 72% reduction of PPM infestation. Although broadleaved cover did not significantly affect the activity of PPM predators along pine edges, PPM nest abundance decreased with increasing species richness of bird predators consistently with the natural enemies hypothesis. Planting broadleaved hedgerows, combined with the conservation of broadleaved remnants, represents an effective management strategy for mitigating PPM infestation in pine plantation landscapes.

The pine processionary moth, Thaumetopoea pityocampa (Denis & Schiffermüller, 1775), is a significant pest of pine and cedar forests in Southern Europe and North Africa. This study aimed to assess pupal mortality of this pest on two host species, Cedrus atlantica and Pinus halepensis, in northern Algeria. A total of 1,382 mature larvae were collected in the field and allowed to pupate under laboratory conditions. Mortality caused by parasitism and entomopathogenic fungi was then assessed. Overall mortality ranged from 13.7 % to 31.1 %, with parasitism contributing 7.0 % - 11.9 % and fungal infections 2.7 % - 6.3 %. Three Diptera parasitoid species were identified: Exorista segregata (Rondani, 1859), Phryxe caudata (Rondani, 1859) (Diptera, Tachinidae), and Hemipenthes sp. (Diptera, Bombyliidae), the latter being recorded for the first time in Algeria. Exorista segregata was the most abundant species, accounting for nearly 65 % of emerging parasitoids. Additionally, the entomopathogenic fungus Beauveria bassiana (Deuteromycotina, Zygomycetes) was identified, indicating potential for biological control despite its low incidence. Key words: Thaumetopoea pityocampa, Pupal mortality, Parasitoid, Entomopathogenic fungus, Biological control, Algeria

Assessing the species ecological responses to ongoing climate change is a critical challenge in environmental science. Rising temperatures, particularly in winter, are altering the distribution patterns of many species, including the pine processionary moth (PPM), Thaumetopoea pityocampa (Denis & Schiffermüller, 1775). This Mediterranean species, a significant defoliator of conifers, is expanding its range northward as winter temperatures increase. The larvae of PPM also pose serious public health risks due to their ability to induce allergic reactions in humans, pets, and livestock. To better understand these ecological shifts, we calibrated three distribution models (Bayesian Additive Regression Trees, Boosted Regression Trees, and Random Forest) based on historical and modern occurrence data compiling of 1769 points, and assessed climate suitability under historical, current and future conditions. Our results show that winter minimum temperatures, summer maximum temperatures, and solar radiation significantly influence the life cycle, and shape the geographical distribution of PPM. Under current conditions, PPM could extend its range further north, but its limited flight capabilities hinder its ability to keep up with the pace of climate change. Future projections suggest continued northward expansion, although solar radiation is expected to limit the northernmost range of PPM. Certain host tree species of PPM are frequently used as ornamental plants, particularly in urban areas, which makes the careful selection of these species a potentially valuable tool for management. Our findings identify regions that are likely to become suitable for PPM colonization, where proactive measures could be implemented.

ABSTRACT Baryscapus servadeii and Ooencyrtus pityocampae are considered the main factors contributing to the mortality of Thaumetopoea pityocampa during the embryonic stage. However, the emergence of these parasitoids is affected by various biotic and abiotic parameters. It is well known that temperatures can limit the emergence and activities of egg parasitoids. O. pityocampae cannot emerge when temperatures exceed 30°C while B. servadeii is more resistant to high temperatures. This difference in thermal tolerance may shape their seasonal activity patterns. Egg parasitoids can adjust their performance and selectivity based on the structure of their host; both O. pityocampae and B. servadeii prefer unscaled eggs or those covered by small scales. Adult egg parasitoids can assess and select their host before parasitizing, showing a preference for eggs located at the ends of batches that are protected. The behavioural strategies of these two egg parasitoids are highly influenced by the morphological traits of their host which can pose obstacles to parasitism. Their preference for eggs positioned at the ends of egg batches suggests a strategy to maximise reproductive success. The emergence dynamics and host selectivity of these parasitoids are shaped by both their intrinsic behavioural adaptations and external environmental conditions and quality of the covering scales.

The pine processionary moth (PPM) causes damage by eating the needles of trees. It was determined that the normal increment and growth decreased in trees affected by this insect depending on the severity of the epidemic. The aim of this study is to determine the diameter and volume increment losses caused by the PPM in trees in the Crimean pine forests of Bartın province. The research material was obtained from nine temporary trial areas determined in the natural Crimean pine forests of Bartın province. Diameter and height measurements were made on all trees in the trial areas and increment cores were taken from a total of 346 trees. The annual diameter and volume increment values were determined for the period 2010-2021. The period 2015-2017 was determined as loss years. Three classes were created as control, moderate, and high harmful, according to the three-year total diameter increment in the damage years. The differences between the diameter and volume increments of the three classes were checked by the ANOVA and the Duncan test. The effect of climate variables on these differences was examined by the Standardized Precipitation Index and the Erinç Precipitation Efficiency Index. It was understood that increment losses are not affected by the amount of precipitation and temperature. It was determined that there was a 29.89% diameter and 26.72% volume increment loss in the moderate harmful group, and a 40.22% diameter and 35.09% volume increment loss in the high harmful group. Since diameter and volume increment losses have a negative impact on tree wealth and business income, some suggestions were developed to reduce insect damage and ensure sustainable forest management.

Abstract This study contributes to the understanding of the insecticidal activity of diatomaceous earth against pine processionary caterpillars in the Thniet El Had National Park, Tissemsilt, Algeria. A number of factors influenced this decision, including the fact that it is a dangerous bug of the Aleppo pine that slows tree growth and poses a health risk to the general people. The microscopic structure of diatomaceous earth revealed a porous structure, demonstrating its water absorption capacity. We tested the effectiveness of diatomaceous earth against caterpillars in petri dishes in the laboratory, and we tested the effectiveness of our diatomaceous earth trap in the field. For the results in the laboratory, the insecticidal activity of diatomaceous earth on caterpillars showed highly significant results, with a lethal concentration 50 of 11.14 mg/cm² and lethal concentration 90 of 14.23 mg/cm². The study of the average mortality of caterpillars showed an increase according to the doses of diatomaceous earth used, as shown by an ascending curve to give the maximum mortality value (10 individuals per repetition) for the dose of 15 mg/cm² after 120 hours of exposure to diatomaceous earth. The application of the diatomaceous earth trap on the field resulted in a mortality rate of 50% of caterpillars, 42.86% of living caterpillars, and 7.14% of pupae. These results indicate that the tested diatomaceous earth can be a solution against this pest, and the diatomaceous earth eco-trap (collar) for pine and cedar processionary caterpillars is considered an excellent integrated pest management tool, non-toxic and environmentally friendly.

Abstract Several species of Lepidoptera with caterpillars bearing urticating hairs are increasing their range in metropolitan France from year to year, such as the pine processionary (Thaumetopoea pityocampa Denis et Schiffermüller 1775) whose presence was historically limited to the south of France, and which is gradually being observed in the north and at higher altitudes. The procession period also seems to be appearing earlier. Climate change could have an impact on the range and phenology of this species, as well as other species of Lepidoptera with caterpillar bearing urticating hairs. Urticating caterpillars, which can trigger diffuse urticariform papules and allergic reactions for human people through contact with the skin, mucous membranes or inhalation, represent a health issue. These caterpillars also cause a health risk for animals and can have an impact on plants due to the resulting defoliation. This risk assessment therefore focused on the risk posed by these urticating caterpillars in areas where they have been established for a long time as well as in areas where they currently do not occur but could be colonized in the short or medium terms. One of the outputs of the evaluation consisted in identifying 55 different species of Lepidoptera with urticating caterpillars, for metropolitan France, but also for the overseas regions, based on the review by Kawamoto and Kumada (1984) and the GBIF database. In addition, detailed sheets for the well‐known species were drawn up, describing in particular their range, their phenology and the period when the urticating stages occur. A literature review as well as data from poison control centres and the analysis of the results of two surveys (of three associations of dermatologists/allergists and of occupational populations at risk) allowed to characterize the contexts of exposure and the human populations at risk. Concerning animal health, in addition to an epidemioclinical description based on the literature, data from veterinary poison control centres were analyzed in the specific case of dog exposure to the pine processionary between 1999 and 2021 in metropolitan french territory. Given the impact of these species of Lepidoptera on ecosystems, due to the defoliation they induce, this scientific opinion investigated the impact of these species on ecosystem services. The socio‐economic impacts of defoliations and risk management measures implemented in the event of an outbreak were studied based on a literature review and simulations for forest recreation. To represent risk for the whole metropolitan France territory, three risk maps of the human population exposure to the pine processionary, the oak processionary and the brown‐tail moth were designed at municipality level. A multi‐criteria analysis was undertaken to characterize danger (urticating caterpillars) and vulnerability of human populations. Then, the municipalities were ranked according to their level of danger and vulnerability. As a result, municipalities have been classified into 5 danger classes and 5 vulnerability classes. Based on a risk matrix with levels of hazard (abscissa axis) and levels of vulnerability (ordinate axis), 5 levels of risk were finally defined and the 34,816 municipalities of metropolitan France were classified according to their level of risk.

Pine processionary moths Thaumetopoea pityocampa and Thaumetopoea wilkinsoni are among the most harmful insects that cause severe damage to pine forests in many countries, including Türkiye. The aim of this study was to evaluate the efficacy of entomopathogenic fungi (EPF) isolates of Beauveria bassiana (PA-4 and KTU-24), Metarhizium anisopliae (KTU-51), and M. floviridae (AS-2) against the 2nd instar larvae of T. pityocampa and T. wilkinsoni under laboratory conditions. T. wilkinsoni eggs were collected from pine trees at Ondokuz Mayıs University Kurupelit Campus in Samsun, Türkiye, in 2021, while T. pityocampa eggs were collected from Kahramanmaraş province, Türkiye, in 2021, and the 2nd instar larvae were used for the experiment. Four fungal isolates were sprayed on the larvae at 2 mL for each concentration (1 × 105 - 1 × 108 conidia mL-1). At a concentration of 1 × 108 conidia mL-1, mortality rates for T. pityocampa larvae were 55.6-100%, while mortality rates for T. wilkinsoni larvae were 56.8-100%. It was found that two isolates of B. bassiana were virulent for both T. pityocampa and T. wilkinsoni, and the KTU-24 isolate was the most virulent isolate, causing the lowest LC50 values ​​​​(2.2 × 105 for T. pityocampa and 4.3 × 105 for T. wilkinsoni) and the shortest mean survival time for both larval species. It is suggested that the KTU-24 isolate can be used in the biological control of pine processionary moth species.