Academic literature on the topic 'Thaumetopoea pityocampa'

Description du sujet. Dans le cadre d’un projet de biocontrôle de la processionnaire du pin, Thaumetopoea pityocampa Denis & Schiffermüller, l’utilisation de parasitoïdes indigènes pour lutter contre ce ravageur a été étudiée au sein du Laboratoire Biocontrôle à l’UEFM (Unité Expérimentale Entomologie et Forêt Méditerranéenne) à l’INRA PACA. Objectifs. Il est nécessaire de rechercher le meilleur hôte de substitution et de mettre au point son élevage. Plus particulièrement, l'espèce Ooencyrtus pityocampae (Mercet) a été étudiée. Méthode. Thaumetopoea pityocampa étant une espèce allergisante, plusieurs hôtes de substitution ont été comparés pour l’élevage des parasitoïdes : Philosamia ricini (Danovan), Nezara viridula (L.) et Halyomorpha halys (Stål). Les caractéristiques biologiques et la fitness des descendants ont été comparées en conditions de laboratoire (25 ± 1 °C, 75 ± 5 % HR, 16L:8D). Résultats. Philosamia ricini est le meilleur hôte de substitution pour l’élevage d’O. pityocampae pour ce qui est de la quantité et de la qualité des individus produits. Conclusions. Cette étude servira de base à une réflexion sur les possibilités d’utiliser ce parasitoïde dans le cadre de la lutte biologique contre certains ravageurs méditerranéens.

The egg parasitoid complex of the pine processionary moth (Thaumetopoea pityocampa) was surveyed for the first time on the Thasos Island, Greece. A total of 96 egg batches containing 20391 eggs were collected between 06 and 10 of September, 2017 from Aleppo pines (Pinus halepensis) at four sites (Skidia, Thimonia, Alyki and Panagia). Four primary parasitoids were identified (Ooencyrtus pityocampae, Baryscapus servadeii, Anastatus bifasciatus and Trichogramma sp.), as well as the hyperparasitoid B. transversalis. Among the parasitoids groups, O. pityocampae was the most common, followed by B. servadeii, whilst the number of other species was low. The highest survival rate was reported for three species: O. pityocampae, B. servadeii and A. bifasciatus, while the highest was the mortality in Trichogramma sp. All emerged adults of O. pityocampae and B. servadeii were female specimens and in A. bifasciatus – males. The number of females of B. transversalis was three times higher than the one of males. Ooencyrtus pityocampae and B. servadeii were the most important parasitoids of T. pityocampa, destroying respectively 27.1% and 9.9% of the host eggs.

Background: Moths of the genus Thaumetopoea are widespread pests in the coniferous and deciduous forests in Bulgaria. Contact with the caterpillars, larval form of different Thaumetopoea species, causes a series of complaints in humans: mainly contact dermatitis (erucism), but also IgE-mediated allergic reactions. The aim of the present pilot study is to investigate the skin reaction after prick tests with allergens from different Thaumetopoea species in a group of people who have frequent contacts with the processionary caterpillars. Material and methods: A group of 42 subjects were surveyed - 37 men and 5 women between the ages of 18 and 87. Specific sensitization to caterpillars of three Thaumetopoea species: Thaumetopoea pityocampa (pine processionary); Thaumetopoea processionea (oak processionary) and Thaumetopoea solitaria (pistachio processionary) was assessed by allergy skin prick tests (SPT) with specially designed caterpillar allergens. Results: Positive allergy skin tests to one or more caterpillar’s allergens were measured in 18 (43%) participants. A simultaneous test with the three allergens from the different Thaumetopoea species showed that in 5 (31%) of the cases, skin hypersensitivity only to allergen from T. pityocampa was present. Monosensitization to T. processionea observed in 2 (12%). The rest 9 (57%) participants with positive skin test show different profiles of polysensitization to Thaumetopoea allergens under study. Conclusions: The evaluation of skin reactivity after SPT with different caterpillar’s allergens outlined the important role of processionary allergens, especially this from T. pityocampa, in the development of IgE-mediated allergic complaints in different groups of forestry professionals. In view of these results, it seems that IgE-mediated hypersensitivity allergic reactions to Thaumetopoea caterpillars are at least as important as those with no allergic mechanism.

A bacterium (strain Tp2T) was isolated from a caterpillar of the pine processionary moth, Thaumetopoea pityocampa (Den. & Schiff.) (Lepidoptera: Thaumetopoeidae), a destructive pine forest pest. The bacterium is a Gram-stain-positive, red-pigmented coccus, oxidase-negative, nitrate-reducing, non-motile and non-spore-forming. Strain Tp2T was subjected to a taxonomic study using polyphasic approach that included morphological and biochemical characterizations, 16S rRNA gene sequence analysis, DNA–DNA hybridization, DNA G+C content analysis, comparative fatty acid profiles, and analyses of quinones and polar lipids. The 16S rRNA gene sequence of strain Tp2T revealed that Arthrobacter agilis DSM 20550T was the closest known strain (98 % 16S rRNA gene sequence similarity). DNA–DNA hybridization of A. agilis DSM 20550T and strain Tp2T resulted in a DNA–DNA relatedness value of 11.9 % (20.2 % reciprocal). The DNA base composition of strain Tp2T was 69.5 mol%, which is consistent with the other recognized members of Actinobacteria that have a high G+C content in their genome. The polar lipid pattern of strain Tp2T consisted of diphosphatidylglycerol (major), phosphatidylglycerol and phosphatidylinositol and unknown glycolipids. The cellular fatty acids were anteiso C15 : 0 and anteiso C17 : 0 and the major menaquinone was MK-9(II-H2). The peptidoglycan type was A3α with an l-Lys–l-Thr–l-Ala3 interpeptide bridge. The above-mentioned characterization qualifies strain Tp2T as genotypically and phenotypically distinct from closely related species of the genus Arthrobacter with validly published names. Strain Tp2T is therefore proposed to represent a novel species of the genus Arthrobacter , described as Arthrobacter pityocampae sp. nov. The type strain is Tp2T ( = DSM 21719T = NCCB 100254T).

The cedar processionary moth, Thaumetopoea bonjeani (Lepidoptera: Notodontidae), is a serious pest of the Atlas cedar Cedrus atlantica in north-western Africa and it is involved in the decline of this endangered tree species. Natural enemies of the cedar processionary moth are poorly known, especially for parasitoids, predators and pathogens of the larval-pupal life stages. Mature larvae were collected and examined in 2014 and 2015 in natural stands of Atlas cedar in the Djurdjura (northern Algeria), in occurrence with pine processionary moth Thaumetopoea pityocampa. The overall mortality rate of larvae of Thaumetopoea bonjeani ranged from 26.4% to 31.1%, with generalist predators and parasitoids being more effective than pathogens. Four primary parasitoid species were recorded, of which four tachinid flies and one braconid wasp, as well as four predatory beetles and one fungus. The most important species were the carabid Calosoma sycophanta and the tachinid Compsilura concinnata. The cooccurrence of T. bonjeani and T. pityocampa may offer to generalist natural enemies an extended period of availa- bility of similar preys, as the two processionary moths have different life cycles. The sharing of natural enemies between the two species of Thaumetopoea can mitigate the outbreaks of both species.

This work deals with the taxonomic study of a bacterium, strain Tp12T, isolated from caterpillars of the pine processionary moth (Thaumetopoea pityocampa Denis & Schiffermüller, 1775; Lepidoptera, Thaumetopoeidae). The isolate was assigned to the genus Brevibacterium on the basis of a polyphasic taxonomic study, including morphological and biochemical characteristics, 16S rRNA gene sequence analysis, fatty acid analysis and DNA G+C content. The highest 16S rRNA gene sequence similarity to this isolate was approximately 96 %, with the type strains of Brevibacterium album and Brevibacterium samyangense. Cellular fatty acids of the isolate are of the branched type, with the major components being anteiso-C15 : 0 and anteiso-C17 : 0. The DNA G+C content was 69.8 mol%. Although the strain was related to B. album and B. samyangense according to 16S rRNA gene sequence analysis, it differed from any known species of Brevibacterium. Based on this evidence, the novel species Brevibacterium pityocampae sp. nov. is proposed, with strain Tp12T (=DSM 21720T =NCCB 100255T) as the type strain.

Caterpillars of the pine processionary moths, Thaumetopoea complex, cause serious defoliation to Cedrus, Pinus, and Pseudotsuga trees. Thaumetopoea caterpillars also have fine hairs on their abdominal tergites that contain a protein that can severely irritate and cause dermatitis in humans and domestic animals. The control of the T. pityocampa pine processionary moth has become necessary in many European countries because of the sanitary risks that are related to larval urtication and the defoliation threat to pine forests and plantations. New research activities have been aimed at the development of eco-friendly, innovative technologies for Integrated Pest Management (IPM) of these moths, particularly in urban parks and woodland recreational areas. This paper describes the recent advances in the use of pheromones in monitoring, mass trapping, and mating disruption related to management of processionary moths T. hellenica and T. pityocampa. According to the results, the use of pheromones may provide a practical alternative to insecticide sprays, as they can be safe and simple as compared to other control methods.

SummaryMating disruption (MD) has been a successful approach for pest control of several lepidoptera. Field trials to evaluate the efficacy of communication disruption of low pheromone load formulation on Thaumetopoea pityocampa were carried out in 2010 and 2011 in an urban park. The efficacy of MD was assessed by comparing male T. pityocampa catches in pheromone traps, between MD and Control areas. In the 1st year of the application the percentage of male inhibition ranged from 85 to 100% during the 1st month of the flight period and 95-100% during the whole flight period in the 2nd year. The pheromone remained in the polymeric matrix was almost 30% after 7 weeks under laboratory aging conditions. Combining the pheromone release results with the male disorientation results we can assume that after 7 weeks the remaining pheromone concentration was still sufficient to achieve MD. This study indicates that air permeation with the major sex pheromone component (Z)-13-hexadecen-11-ynyl acetate, at a rate of 20 g/ha for one application per season, can affect the orientation of T. pityocampa males. Since mating disruption is an environmentally safe method for pest control, it could be a valuable tool to control T. pityocampa in urban areas and parks.

Pine processionary moth (PPM, Thaumetopoea pityocampa) is an active range expanding pest species having significant economic impact in terms of tree growth and public health. A lot is known about its natural history although one important aspect of its life history, diapause, has been so far neglected in spite of its acknowledged importance in pest establishment and dynamics. A few questions related to diapause have been addressed in this PhD project. Although the existence of prolonged diapause (PD) was reported long ago, no study provided its maximum duration. We provide evidence of existence of at least 7 years of PD in one mountain population of PPM, and establish the importance of PD individuals in the sustenance of population density. This study underscores the importance of long-term surveillance of population for understanding the dynamics of PD. Although several studies have been conducted on the incidence of PD in PPM across it natural range, they were often published as forest service or forest health reports and not available to the large public. A collection of these reports, their validation and comparison with data from papers allowed to make a synthesis that included most of the pest range, including the sibling species Thaumetopoea wilkinsoni in the Near East. We suggest that winter conditions at the larval stage influence this decision. Data analysis suggests a strong U-shaped relationship between the incidence of PD and average winter temperature and a linear positive relationship between mortality and proportion of individuals in PD. The result contributes to the advancement of knowledge on the ecology, population dynamics and distribution of the PPM. Previous phenological models of PPM lack the description of dormant prepupal stage and its significance in synchronization of emergence. Besides, no study reported on the occurrence of diapause in PPM in a stage other than pupa. We show how with a weekly sampling during the two-month long procession period of pine processionary prepupae, it was possible to discover that prepupae differentially regulate their development time in such a way that moth emergence of short-lived adults resulted to be concentrated and synchronized in less than one month. Early descending individuals don’t pupate immediately, rather wait as diapausing prepupae for their late counterparts, whereas late-descending prepupae develop into pupae much faster. The finding of prepupal diapause and its significance in synchronization of emergence may improve the existing model of phenology and provide managers with a new tool to handle this pest. Diapause termination mechanism in both univoltine and prolonged diapausing individuals of PPM has been previously hypothesized based on the occurrence of a key period during the pupal stage. By using three proxies of metabolic activity, such as body temperature, O2 consumption, and weight loss, we confirm the hypothesis of existence of a key period (termination) in univoltine and prolonged diapausing individuals of PPM. This finding is a starting point for the study of diapause development in PPM from an ecological point of view. Compared to simple phenomenon of diapause, field of prolonged diapause in insects per se is not vast. A lot of questions regarding the regulation of prolonged diapause are still unresolved. When we consider PPM, the gap of knowledge in this regard is gigantic. Being an important pest of Mediterranean forests, PPM deploys diapause for its success. We know almost nothing about the regulation of diapause in this species. Despite that, this thesis attempted to start the effort of answering a few of thousands of questions on the regulation of diapause in PPM. This project has prepared the ground for several possible future works. Among them, some are: testing the findings in other populations, understanding genetic regulation of diapause and prolonged diapause, understanding the importance of climate change in regulating diapause, improving phenology models and using for predicting the effects of climate change under different scenarios.
La processionaria del pino (PPM, Thaumetopoea pityocampa) è una specie in fase di espansione dell’areale e che causa perdite importanti di crescita degli alberi nonché problemi sanitari all’uoma e altri animali. Nonostante molti studi siano stati condotti su questa specie, alcuni aspetti relativi alla diapausa sono stati finora trascurati anche se riconosciuti come importanti per l’affermazione della specie. Questa tesi si pone l’obiettivo di chiarirne alcuni. La presenza di diapausa prolungata (PD) in Th. pityocampa è nota da tempo ma mancano dati precisi sull’effettiva durata del fenomeno. Con questo studio si è potuto dimostrare che in una valle alpina al limite dell’areale la diapausa si estende fino a 7 anni, con ripercussioni significative sulla dinamica di popolazione. Ciò indica la necessità di una sorveglianza estesa delle popolazioni dell’insetto. Nell’areale della processionaria del pino sono stati svolti vari studi in cui la presenza di diapausa è stata accertata e quantificata, e alcuni di questi sono stati inclusi in rapporti interni di difficile reperibilità. L’accesso a questa informazione e la sua verifica puntuale hanno consentito di produrre una sintesi dei risultati, includendo anche la specie sorella Th. wilkinsoni diffusa in Asia Minore. I risultati mostrano che un fattore importante è rappresentato dalle temperature invernali cui sono esposte le larve. E’ stata infatti trovata una relazione a U tra temperatura invernale e frequenza della diapausa, associata a una maggiore mortalità per gli individui diapausanti. Tale risultato rappresenta un passo in avanti nella documentazione dell’effetto dei fattori ecologici sull’ecologia e sulla dinamica dell’insetto. I modelli di sviluppo disponibili per la processionaria del pino non hanno mai considerato lo stadio di prepupa e l’esistenza di una quiescenza/diapausa che porti a una migliore sincronizzazione degli sfarfallamenti. Grazie a un campionamento settimanale durante il periodo delle processioni di interramento è stato possibile accertare che il periodo di discesa è lungo circa il doppio rispetto allo sfarfallamento, e che le prepupe presentano una diapausa mirata a sincronizzare l’uscita degli adulti e quindi gli accoppiamenti. Il meccanismo si basa su un arresto dello sviluppo nei primi individui che scendono al suolo, che si riduce progressivamente durante il periodo. Queste nuove conoscenze sono di notevole importanza nella definizione di modelli di sviluppo e di previsione delle popolazioni dell’insetto. La conclusione della diapausa pupale in individui univoltini o in diapausa prolungata è stata associata alla presenza di un periodo chiave durante il quale l’individuo decide se proseguire nello sviluppo ad adulto o se rimanere in diapausa. Grazie a misure di alcune variabili non distruttive (temperatura superficiale, consumo di ossigeno, peso corporeo) è stato possibile mettere in evidenza per la prima volta l’esistenza di tale periodo in individui mantenuti a varie condizioni ambientali. Questo risultato rappresenta un enorme passo in avanti nelle conoscenza sulla regolazione della diapausa in questa specie. Nonostante la diapausa degli insetti sia in generale ben nota, le informazioni sulla diapausa prolungata sono scarse e molte domande giacciono irrisolte. Nel caso specifico della processionaria del pino questo ritardo è notevole e allo stesso tempo importante per la regolazione della dinamica di popolazione e quindi dei danni a piante e animali. Questo lavoro contribuisce a chiarire alcune aspetti importanti e apre la strada a studi mirati a conoscere la regolazione genetica della diapausa, gli effetti del cambiamento climatico, e lo sviluppo di modelli in grado di prevedere con affidabilità l’andamento demografico.

In the present work, we studied a common outbreaking Lepidoptera species in Portuguese pine stands – Thaumetopoea pityocampa (Den. & Schiff.) - and one of its potential predators – Parus major (L.). The population dynamics of the immature stages of the Lepidoptera was studied in several types of Pinus pinaster (Aiton) plantations in three different areas: Setúbal Peninsula, Abrantes and National Pine Forest of Leiria. Location and plantation structure was the most important factors determining population density of T. pityocampa. Setubal and Abrantes was highly susceptible to attacks by the Lepidoptera, whereas Leiria had lower densities. Young and homogeneous pine stands was more susceptible to attacks than older and more heterogeneous pines stands. However, a desynchronized population of T. pityocampa, in which the larvae develops during summer instead of during winter, reached high densities also in Leiria. The impact of several mortality factors and climatic conditions on the immature stages of the insect (eggs and larvae), in normal and desynchronized populations are discussed, as well as possible evolutionary implications of the sudden appearance of the new version of T. pityocampa. The break of the pupa diapause and adult emergence times the annual life cycle of this insect. Adults from the desynchronized population emerged earlier than adults from the normal population, which in turn determined the change in the larvae development period. Different factors, potentially affecting the timing of adult emergence in both normal and abnormal populations are also discussed. To study P. Major, nest-boxes were placed in the areas of Setúbal and Leiria and they were monitored during three seasons. The nest-boxes increased the density of breeding and wintering birds in the studied pine plantations, indicating that a lack of natural holes are in fact a limiting factor for this populations. The earliest breeding start for this species was recorded in my study area, indicating that Portuguese coastal pines provide good breeding conditions earlier than in other areas of Europe and North Africa. This leads to an overlap between the end of the larvae stage of T. pityocampa and the beginning of the breeding season of P. major. Key-words: Thaumetopoea pityocampa, Parus major, Pinus pinaster, population dynamics, Portugal.

Dissertação de Mestrado Integrado em Medicina Veterinária
A Thaumetopoea pityocampa, vulgarmente conhecida por processionária, é endémica no sul da Europa. A exposição aos pêlos urticantes, que surgem a partir da 3ª fase larvar, provoca dermatite e urticária de contacto em humanos e nos animais domésticos, constituindo um problema de saúde pública. Em Medicina Veterinária não existe, até à data, nenhum trabalho sobre os seus efeitos na espécie felina. Este estudo retrospectivo relata 6 casos clínicos de felinos que contactaram com a processionária na Península de Setúbal. Tem como principal objectivo a caracterização do quadro clínico, medidas terapêuticas e evolução. Todos os animais foram presentes à consulta nos meses de Fevereiro e Março, altura em que as larvas descem dos pinheiros e formam as típicas procissões, no período decorrido entre 2007 e 2012. A amostra incluiu 3 fêmeas e 3 machos, todos da raça Doméstico de pêlo curto e com idades compreendidas entre 5 meses e 8 anos. O período de tempo decorrido desde o contacto até à consulta variou desde 1 hora a mais de 2 dias. Os sinais clínicos ocorreram de forma aguda com carácter evolutivo. Ao exame clínico observou-se: prurido facial (6/6), ptialismo (5/6), eritema facial (4/6), queilite (3/6), edema facial (3/6), edema lingual ou sub-lingual (3/6), glossite ulcerativa (3/6), anorexia (3/6), lesões ulcerativas orofaciais (2/6), disfagia (2/6), edema submandibular (1/6), vómito (1/6) e edema das extremidades dos membros anteriores (1/6). Foi instituída terapêutica de suporte e sintomática e todos os animais recuperaram completamente. A maioria dos gatos afectados tinha uma idade inferior a 10 meses, o que sugere que os animais jovens correm maior risco de exposição. A cabeça foi a região mais atingida, destacando-se a face e a cavidade oral. Embora alguns gatos tenham apresentado glossite e lesões ulcerativas, nunca se constatou uma evolução necrosante. O contacto com T. pityocampa em felinos é um problema subestimado, tanto na literatura científica como na prática clínica, tornando-se importante sensibilizar os clínicos para esta causa de urticária e dermatite de contacto.
ABSTRACT - EFFECTS OF EXPOSURE TO THAUMETOPOEA PITYOCAMPA IN CATS : REPORT OF 6 CLINICAL CASES - The larval form of Thaumetopoea pityocampa, commonly known as pine processionary caterpillar, is endemic in southern Europe. Exposure to its urticant hairs, which appear from the third larval stage (L5) onwards, induces dermatitis and contact urticaria in humans and animals. Most of the clinicians in small animal veterinary practice are familiar with this threat, however few studies have been published and up to date there are no works concerning its effects in cats. Based on 6 cases, the aim of this retrospective study was to evaluate the evolution of the clinical manifestations of lepidopterism and therapeutic measures that should be implemented. The cases here described were observed from 2007 to 2012, during the months of February and March in the peninsula of Setúbal. The sample included 3 males and 3 females, with ages ranging from 5 months to 8 years and all animals were DSH. The period of time elapsed from exposure and consultation extended from less than 1 hour to more than 2 days. The disease course and progression of clinical signs were acute in all cases. Physical examination findings comprised: facial pruritus (6/6), ptyalism (5/6), facial erythema (4/6), facial oedema (3/6), cheilitis (3/6), lingual or sub-lingual oedema (3/6), ulcerative glossitis (3/6), anorexia (3/6), orofacial ulcerative lesions (2/6), dysphagia (2/6), submandibular oedema (1/6), vomit (1/6) and distal forelimbs oedema (1/6). The medical approach consisted primarily of supportive and symptomatic treatment. All cats recovered completely. All cases occurred in the period of greatest risk of contact. This time coincides with the last larval stage (L5), when the abundance of urticating hairs is the highest and the caterpillars abandon the trees forming a typical procession in order to pupate in the soil. Most of the affected cats were less than 10 months old, suggesting that young animals may be particularly susceptible. The head was the most affected region of the body, especially the face and oral cavity. Although some cats presented glossitis and ulcerative lesions, none progressed to necrosis. To the best of our knowledge, this is the first study reporting several adverse reactions caused by pine processionary caterpillar contact in cats. This problem is underestimated in scientific literature and in clinical practice. It is important to raise awareness among small animal veterinarians to this cause of urticaria and contact dermatitis in cats in endemic areas.

Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia
Thaumetopoea pityocampa is a major pine defoliatior over the Mediterranean Basin. An atypical population with a shifted phenology, ongoing an allochronic differentiation process, was recently discovered in Mata Nacional Leiria, Portugal. The shifted population reproduces in spring achieving its larval development during summer (SP), whereas the sympatric typical population reproduces in summer and has winter larval development (WP). They are reproductively isolated through time, although sharing the same space and host species. General objectives of this work were to characterize the current and potential distribution range of this population, its spatial/temporal genetic and demographic patterns, and ecological adaptations. Field monitoring of presence/absence of SP nests throughout Leiria showed that it is expanding to North and South. Current distribution is restricted to coastal areas, along ca. 120 x 20 km area. Distribution models predict that its distribution will be restricted to coastal areas, due to unsuitable climate inland, being the maximal temperatures of the summer months the main constraint. A phylogeographic study confirmed high SP differentiation from other Portuguese populations. A spatio-temporal sampling along two geographic transects in Leiria zone revealed high stability in time of the genetic composition and structure. A striking demographic result showed that SP tends to apparently displace the WP from the coastal zones suggesting a possible competition phenomenon. Gene flow between the two populations was shown to remain low, even if some SP males actually emerge late. Ecological differentiation was assessed at egg and larval stages. The effect of a wide range of high temperatures on egg survival and development showed higher performances of the SP. Furthermore, SP larvae showed a better ability to cope with host plant water stress, evidencing adaptation to summer feeding activity. This study highlights intra-specific variations on the response of this insect to environmental constraints evidencing ecological adaptation following allochronic differentiation
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Parmi les perturbations attendues des écosystèmes forestiers dans le cadre du changement climatique, les dégâts causés par les insectes ravageurs devraient augmenter en raison notamment de la hausse des températures. Ces dommages devraient réduire la capacité des forêts à stocker du carbone, et donc à atténuer les causes du changement climatique. Plus spécifiquement, il est prédit que l’augmentation des pullulations d’insectes défoliateurs conduise à une diminution importante de la productivité des forêts mais leur impact réel est difficile à quantifier et à comprendre. L’objectif général de ce travail a donc été d’améliorer nos connaissances sur l’impact d’une défoliation sur la croissance d’arbres d’âges contrastés et soumis à différentes contraintes environnementales. Dans un premier temps, ce travail a permis de quantifier la relation entre l’intensité de défoliation de la processionnaire du pin et la perte de production du pin maritime. Une méta-analyse nous a permis de synthétiser les résultats de l’ensemble des 45 études publiées à ce jour sur le sujet. Par la suite, profitant d’une pullulation exceptionnelle de processionnaire du pin pendant l’hiver 2009-2010, nous avons expérimentalement testé l’effet de défoliations variant de 25 à 100% en interaction avec l’âge des peuplements de pin maritime. Nous concluons que les pertes de production sont proportionnelles à l’intensité de défoliation et augmentent avec l’âge de l’arbre.L’évolution du climat étant susceptible de favoriser la combinaison de différents stress, nous nous sommes également intéressés aux effets cumulés de la défoliation et du stress hydrique sur la croissance de l’arbre. Notre étude révèle que la défoliation et le stress hydrique ont des effets additifs sur la croissance du pin maritime. Nos résultats confirment la complexité de la réponse éco-physiologique de l’arbre à la défoliation. L’étude des réserves carbonées et azotées nous a permis d’explorer les possibles mécanismes sous-jacents à l’effet d’une défoliation. Plus qu’une simple diminution de la fixation carbonée par altération de l’appareil photosynthétique, nous proposons que la défoliation affecte la croissance via des processus de limitation en ressources carbonées et azotées. Les réserves carbonées n’étant affectées qu’en début de saison, nous émettons l’hypothèse d’une limitation azotée de l’arbre après défoliation. Ainsi, la défoliation et le stress hydrique pourraient diminuer conjointement la disponibilité en eau et en ressources minérales, ce qui expliquerait leurs effets additifs sur la croissance de l’arbre
In the context of climate change, forest pest outbreaks, among other biotic disturbances, are expected to be more frequent in response to increasing temperatures. The resulting damage is likely to adversely affect forests net primary production and their contribution to climate mitigation via carbon sequestration. More specifically, insect defoliators are to predicted to be more prevalent in the future but their real impact on forest productivity is difficult to evaluate and interpret. Our main objective was then to improve our understanding of insect defoliation impact on tree growth at different tree ages and under various climatic conditions.First, we assessed the relationship between the intensity of pine processionary moth defoliation and maritime pine growth loss. We carried out a meta-analysis to summarize the outcomes of the 45 published studies that addressed this issue. Then, we took advantage of a severe pine processionary moth outbreak to set up a large field experiment where we controlled for both the age (from 3 to 40 years old) and the defoliation rate (from 25 to 100%) of Pinus pinaster trees. We showed that radial growth losses were proportional to defoliation intensity and more important in older trees.As the combination of several disturbances is likely to be more frequent under climate change, we developed a manipulative experiment to quantify the cumulative impact of water stress and defoliation on maritime pine tree growth. We found additive detrimental effects of water stress and defoliation on maritime pine tree growth.Our results confirm that tree response to defoliation, including various eco-physiological processes, is complex. To decipher the underlying mechanisms we analyzed the dynamics of nutrient and carbohydrates pools in defoliated trees during the growing season. Our findings suggest that defoliation affect tree growth through resource limitation rather than via a reduction of carbon fixation due to altered photosynthesis. Since carbohydrates pools were only affected early in the season, our results support the hypothesis of a nitrogen limitation in trees following defoliation. Additive effects of defoliation and water stress may then be explained by similar adverse consequences on water flow and nitrogen uptake

L’évaluation de la santé des écosystèmes forestiers nécessite la mise en place de stratégies de surveillance au sol applicables sur le long terme et selon un continuum d’échelles spatiales. Entre les réseaux de placettes permanentes élaborés de façon empirique à l'échelle européenne et les protocoles d’observation à portée très locale, peu de stratégies d’échantillonnage des dommages forestiers ont été validés à l'échelle du paysage (de quelques centaines à plusieurs milliers d’hectares), qui est pourtant celle de l'aménagement forestier. Pour optimiser les performances de l’échantillonnage des dommages forestiers trois critères ont été envisagés : les caractéristiques du paysage, la variabilité des estimations à différentes échelles spatiales et le coût des observations et des déplacements. Pour cela, deux paysages de forêt cultivée de pin maritime ont été suivi de façon intensive. L’usage de statistiques non-paramétriques (bootstrap, simulations géostatistiques) et des statistiques spatiales a été privilégié pour optimiser la répartition de l’effort d’observation au sein de plans d’échantillonnage emboîtés. Dans un premier temps, l’optimisation des réseaux systématiques d’observations actuels (Réseau Européen – ICP Forest level I, Inventaire Forestier National) à été envisagé dans le cadre d’une stratégie de suivi simultané de l’ensemble des dommages forestiers (biotiques ou abiotiques). Puis, des stratégies d’échantillonnage spécifiques ont été envisagées pour deux insectes ravageurs (la chenille processionnaire du pin Thaumetopoea pityocampa et le scolyte Ips sexdentatus) afin de prendre en compte de façon explicite la distribution spatiale de leurs dommages dans l’échantillonnage. Les résultats montrent qu’il est envisageable d’assoir un protocole d’inventaire des dommages forestiers sur les réseaux d’observations existant à l’échelle nationale à condition de porter la densité d’échantillonnage à environ 1 placette pour 700 ha. La configuration optimale des placettes réside alors dans l’observation de 25 arbres, sélectionnés sans discrimination de statut social et intégrant pour partie les arbres en lisières de peuplement (20%). Seules les populations de T. pityocampa ont montré une structure spatiale sur plusieurs dizaines de kilomètres. Un plan d’échantillonnage systématique, d’une maille carrée comprise entre 2 km et 3km, semble un bon compromis pour l’estimation et la cartographie des densités de population de cette chenille défoliatrice. En revanche, les réseaux systématiques d’observations s'avèrent inadaptés pour l’évaluation de dégâts de très faible intensité et/ou agrégés dans l’espace comme ceux des scolytes. Ainsi l’étude rétrospective de dégâts post-tempête 1999 de I. sexdentatus a montré l'intérêt d’une stratégie d’échantillonnage par cheminement adaptatif le long des pistes forestières. L’utilisation des lisières forestières en tant qu’«arbres sentinelles» apparaît prometteuse et ses applications pratiques sont proposées pour la surveillance sanitaire à l’échelle du paysage
Forest ecosystem health assessment relies on long-term and multiple scales sampling strategies. Neither European networks of permanent plots developed empirically, nor local observation protocols can produce reliable estimates of forest damages over areas ranging from a few hundred to several thousands of hectares. Little attention has been paid to the development of robust sampling designs at the landscape scale, which is however the operational one for forest management. Three criteria were considered to optimize the performance of forest damage sampling: landscape features, variability estimates at different spatial scales and logistics costs of observations. Intensive monitoring was performed on two landscapes of maritime pine plantation forests. Nonparametric statistics (bootstrap, geostatistical simulations) and spatial statistics were used to optimize allocation of sampling effort within nested sampling designs. Firstly, the monitoring of all types of forest damage (biotic or abiotic) was investigated through the optimization of sampling schemes currently applied at the national scale (European Network - ICP forest level I and National Forest Inventory). Then, specific sampling strategies were developed for two insect pests (the defoliator Thaumetopoea pityocampa and the bark beetle Ips sexdentatus), taking into account the spatial distribution of their damage. Increasing the sampling density of national plot networks up to 1/700 ha would be necessary for forest damage survey at the landscape scale. The optimal configuration of inventory plots lies in the observation of about 25 trees, selected without discrimination of social status and partly integrating trees at stand edges (20%). At a large scale, only populations of T. pityocampa showed a spatial structure over several kilometers. A systematic sampling plan, with a square grid between 2 km and 3 km, seems to be a good compromise for estimation and mapping of its nest density. However, systematic plot networks are inadequate for assessing rare and spatially clustered phenomenon such as damage caused by bark beetles damages. A retrospective post-storm 1999 survey of I.sexdentatus damages emphasizes the effectiveness of an adaptive roadside sampling method to monitor this type of damage. The use of forest edges as "sentinel trees" seems promising and its practical applications are proposed for forest health monitoring at the landscape scale

Les peuplements forestiers mélangés subissent moins de dégâts d’insectes herbivores que les peuplements purs, du fait d’une diminution de l’accessibilité à la ressource ou/et d’une amélioration des conditions de survie de leurs ennemis naturels. Pour vérifier ces hypothèses, nous avons étudié un insecte ravageur, la processionnaire du pin (Thaumetopoea pityocampa), et ses insectes parasitoïdes dans le contexte de monoculture de pin maritime (Pinus pinaster) de la forêt des Landes de Gascogne, où persistent localement des zones de milieu ouvert (parefeux, coupes rases) et des boisements d’essences feuillues (haies en bordure de peuplement de pin, ripisylves, îlots). Nous avons pu démontrer que :(1) La colonisation des parcelles de pin par la processionnaire est limitée parla présence de haies de feuillus en lisière de parcelle. En effet, les feuillus jouent un rôle de barrière physique, entravant la détection visuelle des pins par la femelle de processionnaire lorsqu’elle recherche un site d’oviposition.(2) La longévité des principaux parasitoïdes, spécialiste et généraliste, des oeufs de processionnaire est favorisée par la consommation de miel lat produit pardes pucerons du chêne. Cela permet notamment à l’espèce généraliste, qui émergedeux mois avant la processionnaire, de prolonger sa présence dans le milieu et doncd’augmenter sa probabilité de parasiter des pontes de processionnaire.(3) Les chrysalides de processionnaire du pin survivent mieux dans le sol desmilieux ouverts que sous couvert forestier (de pin ou de feuillus), du fait d’unetempérature et d’une humidité plus élevées. L’association de pins et de milieuxouverts favorise la processionnaire par complémentation des habitats, tandis que laprésence de feuillus peut représenter un piège écologique pour les chenilles aumoment de l’enfouissement.(4) À l’échelle du paysage, les peuplements de pin maritime au centre depaysages hétérogènes sont moins infestés que dans les paysages de monoculture.De plus, les niveaux d’infestation de la processionnaire diminuent lorsque laproportion de feuillus dans le paysage environnant augmente.Ces résultats sont interprétés en fonction des mécanismes écologiquesexpliquant la relation entre diversité et herbivorie. Des possibilités de transfert vers lagestion forestière de la forêt des Landes de Gascogne sont proposées, ainsi que desperspectives en termes de recherche scientifique
Mixed forests are less prone to insect damage than pure forests because ofreduced host accessibility and/or improved control by natural enemies. To test thesehypotheses, we have studied the ecology of the pine processionary moth (PPM)(Thaumetopoea pityocampa) and its parasitoid, in a monoculture of maritime pine(Pinus pinaster) plantations, the Landes de Gascogne forest. There, open areas(firebreaks, clear cuts) and patches of broadleaved woodlands (hedgerows, riparianforest, natural forest remnants) still persist locally. In this study we have shown that:(1) Pine stand colonization by PPM was limited by the presence ofbroadleaved hedgerows at stand edge. Broadleaved trees formed physical barriersdisrupting the visual detection of pine trees by PPM females when searching for anoviposition site.(2) The longevity of the two main PPM egg parasitoids increased whenspecimen were fed with honeydew produced by oak aphids. The generalist species,which emerges two months before PPM, could benefit from this longer lifespan tooverlap its host emergence.(3) PPM pupae survived better in the soil of open areas than under forestcovers (pine or broadleaved trees), because of higher temperature and humidity. Theassociation between pine stands and open areas benefits PPM through habitatcomplementation, whereas the presence of broadleaved trees may act as anecological trap for PPM caterpillars.(4) Maritime pine stands within heterogeneous landscapes exhibited lowerPPM infestations than similar stands within pine monocultures. PPM infestation levelsdecreased with increasing percent broadleaved area in the surrounding landscape.These results are discussed according to the ecological mechanisms whichmay explain the relationship between insect herbivory and tree species diversity.Perspectives for improved PPM management in the Landes de Gascogne forest, andfor further scientific research are proposed

La processionnaire du pin, thaumetopoea pityocampa (den. Et schiff. ) (lep. , thaumetopoeidae), defoliateur des essences resineuses est en phase de culmination permanente dans les reboisements a pinus halepensis mill. Du barrage vert en algerie. Le rythme d'emergence et d'activite des adultes, la distribution spatiale des pontes, le rythme des eclosions, la phenologie larvaire et notamment les departs en processions de nymphose, ont ete analyses a l'aide de dispositifs experimentaux, tant dans la nature qu'au laboratoire. Les especes clefs du complexe des parasitoides ont ete retrouvees a djelfa ; leur efficacite s'est montree dependante de la densite de l'hote et des possibilites de coincidence phenologique avec ce dernier. Les effectifs des ooparasitoides sont limites par une mortalite des populations diapausantes decoulant d'une chute des pontes au sol resultant elle-meme du comportement alimentaire des chenilles nouveau-nees, qui se nourrissent des aiguilles porteuses. Les parasitoides larvo-nymphaux, erigorgus femorator (hym. , ichneumonidae), peu abondant en regle generale dans l'aire de repartition du ravageur, a ete constamment observe. Son action a ete dans certains cas plus importante que celle de phryxe caudata (dipt. , tachinidae). Les possibilites de coincidence de villa brunnea (dipt. , bombyliidae), parasitoide nymphal, avec son hote ont ete evaluees en fonction de la nature des sites potentiels d'enfouissement des chenilles. La mortalite des chenilles est importante avant la saison hivernale. La contrainte trophique, lors de la recuperation des arbres apres une defoliation, engendre une mortalite et des perturbations physiologiques des chenilles, des chrysalides et des papillons. L'aptitude a une diapause nymphale a caractere biennal chez une proportion non negligeable de la population est susceptible d'expliquer le maintien du ravageur, dans les reboisements de djelfa malgre les fortes pressions selectives de la region subsaharienne.

The chemical elicitor methyl jasmonate (MeJA) could replace insecticides in Europe and Asia for protection of young conifers against the pine weevil (Hylobius abietis). This thesis mainly focuses on the effects of MeJA treatment on chemical defenses of conifers from seedling batches with documented field resistance. Tissues of three pine species and one spruce species, with various treatments, were here extracted in hexane, whereafter volatile contents of tissues were separated and analyzed by 2D GC-MS. Induced responses of seedlings of Maritime pine (Pinus pinaster) and Monterey pine (Pinus radiata) to the folivore pine processionary (Thaumetopoea pityocampa), and the phloem-feeder H. abietis, have been studied. Amounts of mono- and sesqui-terpenes (and also non-volatile resin) in conifer tissues (needles and phloem) were less induced by T. pityocampa than by H. abietis. The MeJA-treated seedlings of Scots pine (Pinus sylvestris) changed their composition of phloem monoterpenes (induction of (-)-β-pinene), and were better protected in field than the seedlings of Norway spruce (Picea abies), which increased their total amounts of monoterpenes. Orientation bioassays with H. abietis showed deterrent effects of (-)-β-pinene, (+)-3-carene, (-)-bornyl acetate and 1,8-cineole. Conversely, (-)-α-pinene (induced in P. abies but not in P. sylvestris) was non-deterrent. MeJA-treated seedlings fed on by H. abietis contained higher amounts of the H. abietis antifeedant 2-phenylethanol, in tissues and emissions. Phloem of control seedlings instead induced the (+)-α-pinene, which is one of the enantiomers of the H. abietis attractant α-pinene. In response to MeJA treatment, the relative amounts of the (+)-α-pinene increased in the phloem of  P. radiata, while it decreased in P. pinaster phloem. The preference of H. abietis in the field for P. radiata before P. pinaster may be explained by these changes in enantiomers of the H. abietis attractant α-pinene.
Barrträd är viktiga för skogsindustrin. I Sverige består 57% av ytan av produktiv skogsmark, och av dessa träd utgörs 80% av gran och tall. Som försvar mot insekter och sjukdomar, producerar barrträden kådämnen. För unga barrträd i Europa och Asien är snytbaggen (Hylobius abietis) en allvarlig skadegörare, som orsakar skogsnäringen stora kostnader. För att skydda små gran- och tallplantor före utplanteringen, skulle växthormonet metyljasmonat (MeJA) kunna användas. I denna avhandling har effekter av MeJA-behandling och insektsangrepp undersökts på de två viktigaste barrträden i Sverige, tall och gran (Pinus sylvestris och Picea abies) och på två arter i medelhavsområdet (Pinus radiata och Pinus pinaster). De kemiska försvarsämnena i barrträd har analyserats för att utvärdera effekterna av MeJA-behandling. Vävnader från barrträd med olika behandling har extraherats i organiska lösningsmedel och dofterna från plantorna har insamlats genom fastfas-mikroextraktion. De flyktiga ämnena har separerats och identifierats med hjälp av gaskromatografi och masspektrometri (GC-MS). Dessutom har optiskt aktiva doftämnen separerats med hjälp av en tvådimensionell GC-MS. Plantornas olika försvarsreaktioner har studerats vid angrepp av snytbaggen, som är en floemätare, och av tallfjärilslarv (Thaumetopoea pityocampa), som huvudsakligen äter barr. De lättflyktiga ämnena (mono- och seskviterpener) och de icke-flyktiga ämnena (kådsyror) ökade mer i stam och barr från angrepp av H. abietis än av T. pityocampa. Sammansättning av monoterpener ändrades i de MeJA-behandlade tallplantorna i Sverige, specifikt ökade (-)-β-pinene i stamfloemet. Tallplantorna var bättre skyddade i fält än granplantorna, där den totala mängden monoterpener ökade. (-)-β-Pinene, (+)-3-carene, (-)-bornyl acetate och 1,8-cineole visade sig ha en negativ effekt på snytbaggens orientering mot talldoft i orienteringstester. En av monoterpenerna, (-)-α-pinene, som av MeJA-behandlingen inducerats i granen, men inte i tallen, hade ingen negativ effekt på snytbaggen. MeJA-behandlade tallplantor som angripits av snytbaggen, innehöll större mängder av snytbagge-äthämmaren 2-fenyletanol, både i vävnader och i emissioner. Stam från kontrollplantor inducerade istället (+)-α-pinene, vilken är en av de optiska isomererna av snytbagge-attrahenten α-pinene. För de spanska arterna, som svar på MeJA-behandling, ökade de lättflyktigaste terpenerna i barren hos P. radiata men inte hos P. pinaster, vilken redan innehöll en hög terpenhalt. De relativa mängderna av (+)-α-pinene ökade också i stammen hos P. radiata, medan de minskade i P. pinaster. I fält väljer snytbaggen att gå till P. radiata- framför P. pinaster-plantor, vilket kan vara kopplat till de skillnader i α-pinene-isomerer, vilka här har observerats.

QC 20160304

This thesis describes the effect of elevation on the abundance of forest insects along steep mountain slopes, to be used as a spatial analogue of climate change. The elevational gradients in different places in Europe were used as a proxy for the temperature change, using the lapse rate of 0.6 °C every 100 m. Elevational gradients provide an optimal experimental setting to test the relationship between temperature variation and herbivory. Direct and indirect (through the host plant and by the natural enemies) effects of the temperature were checked. The tree quality was measured by leaf toughness, leaf size, C/N ratio, tree diameter and height and, for cone and seed insects, by the length of cones. Insect herbivores were taken into account because they are amongst the most important primary consumers of forest ecosystem, even when they are studied at endemic density as in the present study. The response to the changing temperature was checked for insects guilds (leaf sap feeder, chewers, gall makers, miners) in the Chapter 2, for selected insect species like pine processionary moth (Thaumetopoea pityocampa) in Chapter 3, and also for cone and seed insects of Norway spruce (Cydia strobilella, Dioryctria abietella, Ernobius abietis, Strobilomyia anthracina) in Chapter 4. We concentrated on four main European tree species (Fagus sylvatica, Larix decidua, Picea abies, Pinus sylvestris) because they are the most important trees regarding their abundance and economy value. In the Chapter 1 we used a large data set where we measured leaf herbivory and leaf traits along steep elevational gradients in different biogeographical regions of Europe. We found either neutral or positive effect of increasing temperatures on herbivory while no clear effect of biotic interactions emerged. Among guilds, chewers and leaf miners responded more often than sap feeders and gall makers to temperature. The response to temperature of different host species varied strongly, with conifers more sensitive than broadleaves (Fagus sylvatica). There was a clear elevational pattern of toughness and leaf size (except for Larix decidua) but leaf traits were almost never related with changes in herbivory. There was not interaction between the herbivory guilds except for the miners and chewers of Larix decidua. This community approach (like dividing the insect species into the guilds) is, however, crucial to help understanding the ecosystem level response of insect herbivory to temperature. In the Chapter 3 the abundance of the nests of pine processionary moth (Thaumetopoea pityocampa) along two elevational gradients in southern Spain (Sierra Nevada mountains) was considered. The number of nests increased with elevation, which is opposite to what was expected. Possible explanatory factors were searched in stand conditions (tree density, host percentage), tree quality (tree height, needle toughness, C/N ratio, needle length), egg parasitoids, and possible competitors (leaf sap feeders and chewers). Winter temperature did not explain moth abundance, which was in turn explained by tree height, leaf C/N, but mainly by a higher realized fecundity at high elevation, likely linked to better growth conditions, and by higher egg parasitism at lower elevation. In Chapter 4 the colonization of Norway spruce mature cones by cone and seed insects was analyzed along four alpine elevational gradients (three in Italy, one in France). Specialised insects feeding on seeds (Cydia strobilella and Strobilomyia antracina) did not respond to temperature whereas generalits species feeding on cone tissues did (Dioryctria abietella and Ernobius abietis). There was also a significant interaction, as the seed feeder Cydia strobilella affected positively the generalists Dioryctria abietella and Ernobius abietis. Generally, all chapters based on the elevational gradient approach provided results useful to better understand the effect of future climate change on insect herbivores, although many of the interactions among elevation, host plant, and insects are still to unveil
In questa tesi vengono presentati i risultati di uno studio svolto lungo gradienti altitudinali per verificare la risposta di insetti forestali alla temperatura. A questo scopo sono stati scelti vari siti in Europa, in modo da coprire varie situazioni climatiche e considerando in ciascuno di essi il gradiente altitudinale come analogo spaziale del cambiamento climatico, in relazione al tasso di riduzione della temperatura di 0.6°C ogni 100 m di quota. Sono stati considerati gli effetti diretti e indiretti della temperatura sulle principali categorie funzionali di insetti, considerati a livelli endemici di densità. La qualità della pianta è stata considerata mediante indicatori come la durezza delle foglie, il rapporto C/N, le caratteristiche dimensionali degli alberi. L’effetto della quota sulla fitofagia è stato positivo o indifferente in relazione alle categorie funzionali e alle piante ospiti. Insetti masticatori e minatori fogliari hanno risposto in un maggiore numero di casi rispetto a fitomizi e galligeni, mentre le conifere (abete rosso, larice, pino silvestre) hanno presentato risposte più chiare rispetto alle latifoglie (faggio). Sono stati messi in evidenza effetti positivi della quota su dimensione e durezza delle foglie (eccetto il larice) pur non trovando un legame significativo con la performance degli insetti. Non sono stati inoltre evidenziati fenomeni di competizione e facilitazione tra categorie ecologiche, con l’unica eccezione del larice. Uno studio specifico ha riguardato l’analisi dell’abbondanza dei nidi di processionaria del pino lungo gradienti altitudinali nella Sierra Nevada in Spagna meridionale. È stato osservato che i nidi aumentano con la quota, fatto che contrasta con i modelli previsionali esistenti per questa specie. Sono stati quindi analizzati alcuni dei potenziali fattori esplicativi quali le caratteristiche del popolamento, la qualità degli aghi, la parassitizzazione delle uova e l’azione dei competitori. La temperatura invernale non spiega la distribuzione altitudinale dei nidi, che invece risponde ad alcune caratteristiche della pianta ma soprattutto alla fecondità, che aumenta con l’altitudine, e al parassitismo, che diminuisce decisamente con l’aumentare della quota. In un ulteriore studio specialistico sono stati considerati alcuni insetti dei coni dell’abete rosso le cui tracce erano reperibili in coni maturi caduti al suolo lungo 4 gradienti altitudinali alpini, in Italia e in Francia. Gli insetti specializzati nel nutrirsi di seme (Cydia strobilella e Strobilomyia anthracina) non hanno risposto alla variazione di altitudine mentre gli insetti generalisti consumatori dei tessuti del cono (Dioryctria abietella e Ernobius abietis) hanno risposto in modo negativo all’aumentare della quota. E’ stato anche possibile mettere in evidenza una interazione positiva tra lo specialista C. strobilella e le due specie generaliste. Complessivamente gli studi svolti nell’ambito della presente tesi hanno fornito risultati utili a comprendere gli effetti del cambiamento climatico sull’attività trofica di alcuni insetti forestali, tuttavia si ritiene che sussista ancora dell’incertezza sulle previsioni da svolgere in merito. Si auspica che per la continuazione degli studi vengano prese in maggiore considerazione le interazioni tra altitudine, pianta ospite e insetti