Setae from the pine processionary moth (Thaumetopoea pityocampa) contain several relevant allergens

BACKGROUND: Pine processionary larvae produce urticating hairs (setae) that serve for protection against predators. Setae induce cutaneous reactions in animals and humans. The presence of toxic or allergic mechanisms is a matter of debate. OBJECTIVES: To detect the presence of allergens in setae and to characterize them. MATERIALS AND METHODS: Setae extracts were characterized by gel staining and immunoblot, with sera from patients with immediate reactions and positive prick test reactions, as well as a rabbit antiserum raised against setae. Setae proteins were fractionated by high-performance liquid chromatography. The most relevant allergen was analysed by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS), and its sequence was deduced from an expressed sequence tag bank. Results. Setae contained at least seven different allergens. The most intense detection corresponded to a protein of MW ~ 14,000 that was similar to thaumetopoein, a previously described protein with mast cell-degranulating properties. MALDI-MS-based de novo sequencing provided a partial amino acid sequence different from that of the previously described allergen Tha p 1, and it was named Tha p 2. This allergen was detected in 61% of patients, and it is therefore a new major caterpillar allergen. CONCLUSIONS: Penetration of the setae from the pine processionary caterpillar delivers their allergenic content in addition to causing mechanical or toxic injury.This work was supported by URTICLIM, a French project funded by the ‘Agence Nationale de la Recherche’ (ANR 07BDIV 013). Ana I. Rodriguez-Mahillo is a beneficiary of contract CA07/00046 from the Instituto de Salud Carlos III, Ministerio de Ciencia e Innovacion, Spain.S

Stimulation of tree defenses by Ophiostomatoid fungi can explain attack success of bark beetles on conifers

• Our aim is to present why the hypothesis, that Ophiostomatoid fungi play an important role in the establishment of most bark beetle species on living conifers, is valuable. • After summarizing knowledge about the relationships of bark beetles with conifers and fungi, we conclude that controversy results from misinterpretations when using fungal pathogenicity to demonstrate the role of Ophiostomatoid fungi in beetle establishment on host trees. • We demonstrate that fungal pathogenicity is not the right parameter to appreciate the role of fungus in beetle establishment on host trees. We argue that artificial low density inoculations that allow the appreciation of fungus ability to stimulate tree defenses and thus to help beetles in overcoming tree resistance must be used in complement to mass inoculations. In both cases, results must be expressed in terms of tree defense stimulation rather than in terms of tree killing. (i

Observations symptomatologiques et roles possibles d'Ophiostoma minus Hedgc. (Ascomycete : Ophiostomatales) et de Tomicus piniperda L. (Coleoptera : Scolytidae) dans le deperissement du pin sylvestre en foret d'Orleans

Le dépérissement du pin sylvestre en forêt d’Orléans (France) se caractérise par une chute d’écorce, l’existence de granulations noirâtres en surface de l’aubier et un bleuissement en profondeur de celui-ci. Le jaunissement du feuillage est généralement postérieur à la chute d’écorce, mais peut parfois la précéder. Les arbres en situation difficile paraissent préférentiellement atteints, mais de nombreux arbres dominants le sont également. Deux champignons à potentialités pathogènes ont été isolés des arbres malades : Ophiostoma minus (Hedgc.) Syd. et Syd. et Leptographium wingfieldii Morelet. Les relations entre O. minus et le dépérissement ont conduit à formuler l’hypothèse que ce champignon pouvait avoir un rôle dans la maladie, bien que l’on n’ait pu en reconstituer les symptômes par inoculations artificielles localisées. Tomicus piniperda joue très vraisemblablement un rôle dans la dissémination de O. minus d’une parcelle forestière à l’autre. L’association entre les 2 organismes apparaît cependant fortuite et l’on ignore le rôle de T. piniperda dans l’inoculation de O. minus aux arbres sains. Une étude des symptômes précoces et des premières phases du dépérissement s’avère nécessaire.The dieback of Scots pine (Pinus sylvestris L.) in the Orleans Forest (France) are characterized by the fall of the bark, the presence of black granulations on the sapwood surface and with a bluestain inside. The foliage generally turns yellow after the bark has fallen, but sometimes before. The trees located in poor sites seem to be preferentially stuck, but many dominant trees also. Two potentially pathogenic fungi were isolated from the dying trees : Ophiostoma minus (Hedgc.) Syd. et Syd. and Leptographium wingfieldii Morelet. The relationships between O. minus and the dieback lead to hypothesize that this fungus may have a role in the disease, in spite of the failure to reproduce the symptoms by artificial localized inoculations. Tomicus piniperda seems to play a positive role in the dissemination of O. minus from one plot to another in the forest. Nevertheless, the relationships between these 2 organisms seems to be fortuitous and the role of the beetle in introducing the fungus in the healthy trees is unknown. A study of the early symptoms and of the first stages of disease is necessary

Can phloem phenols be used as markers of scots pine resistance to bark beetles?

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Fungal flora associated with Ips typographus: Frequency, virulence and ability to stimulate the host defence reaction in relation to insect population levels.

This study was aimed at determining the composition of Ips typographus L. (Coleoptera: Scolytidae) associated fungal flora in France, its virulence, and its ability to stimulate host defence reactions. The relationship between these parameters and the beetle population levels was also considered. The study was conducted in 2001, 2002, and 2003 in Norway spruce (Picea abies (L.) Karst.) stands, with different bark beetle damage levels. In each stand, the frequency of association between fungi and I. typographus was determined. The virulence of the most frequent species was assessed through mass inoculations on living spruce trees. The ability to stimulate the host defence reactions was estimated with low-density inoculations. The most frequent species, Ophiostoma bicolor Davids. & Wells, Ophiostoma piceaperdum Rumbold, and Ophiostoma tetropii Mathiesen, were all pathogenic. Ophiostoma piceaperdum also induced intense defence reaction zones, suggesting that it could play a role in I. typographus population establishment on living trees. However, significant correlations between fungal frequencies and damage of the current year were observed only with O. tetropii or O. bicolor, and no relationships between damage of the previous year and fungal frequencies were found. The effects of some fungal species on beetle population dynamics was suggested, but selection of species during epidemic condition was not confirmed.La composition de la flore fongique associée à Ips typographus L. (Coleoptera : Scolytidae), sa virulence et son aptitude à stimuler les défenses de l'hôte, ainsi que les relations entre ces paramètres et les niveaux de population de l'insecte, ont été étudiés en France. L'étude a été menée en 2001, 2002 et 2003 dans des peuplements d'épicéa (Picea abies (L.) Karst.) où les niveaux de dégâts dus aux insectes différaient. Les fréquences d'association entre les champignons et I. typographus y ont été estimées. La virulence des espèces majoritaires a été évaluée avec des inoculations massives sur des arbres vivants et leur aptitude à stimuler les réactions de défense, avec des inoculations ponctuelles. Les espèces majoritaires, Ophiostoma piceaperdum Rumbold, Ophiostoma bicolor Davids. & Wells et Ophiostoma tetropii Mathiesen, se sont toutes révélées pathogènes. Ophiostoma piceaperdum a aussi induit des réactions de défense importantes et pourrait ainsi participer à l'établissement des insectes sur les arbres vivants. Néanmoins, seules les fréquences d'O. tetropii et O. bicolor ont été corrélées avec les dommages de l'année en cours et aucune relation n'a été observée entre les fréquences d'association et les dommages antérieurs. Nos résultats suggèrent l'implication d'espèces fongiques dans la dynamique des populations d'insectes mais ne confirment pas la sélection d'espèces au cours d'une épidémie

Could phenols of the phloem be used as markers of conifer resistance to bark beetles ?

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The virulence of phytopathogenic fungi associated with the bark beetles Tomicus piniperda and Orthotomicus erosus in Tunisia

International audiencePhytopathogenic fungi associated with the bark beetles Tomicus piniperda and Orthotomicus erosus were isolated in various pine forests of Tunisia. Tomicus piniperda and its galleries yielded Leptographium wingfieldii, Ophiostoma minus, and Ophiostoma ips. Ophiostoma minus was the most frequent species associated with T. piniperda, in both the attacking and the emerging beetles. It was collected from most investigated forests, whereas O. ips and L. wingfieldii were obtained only from forests located in Central and Northern Tunisia. Frequencies of association with T. piniperda were always low, reaching 11.1% only once, for O. ips. Ophiostoma ips was the only blue stain fungus associated with O. erosus and its galleries. It was found in all the localities, but at a low and variable frequency, exceeding 15% very rarely. The virulence of 16 fungal isolates was tested by single inoculations into Pinus halepensis (Aleppo pine) at two localities. Differences were detected among species; L. wingfieldii was the most virulent and O. minus the least virulent species in terms of phloem reaction zone formation and fungal growth in the phloem. In a separate experiment, mass inoculations (400 and 800 inoculations per m2 of bole on 1-m high belts) were performed with two isolates of L. wingfieldii on Aleppo pine and on Pinus brutia (Brutia pine). Three months later, measurements of sapwood status (% of conductive transversal section) and of its specific hydraulic conductivity, as well as of the phloem reaction zone lengths, did not show any isolate or density effect. At these experimental sites, Brutia pines appeared significantly more susceptible than Aleppo pines

Sentinel trees as a tool to forecast invasions of alien plant pathogens.

Recent disease outbreaks caused by alien invasive pathogens into European forests posed a serious threat to forest sustainability with relevant environmental and economic effects. Many of the alien tree pathogens recently introduced into Europe were not previously included on any quarantine lists, thus they were not subject to phytosanitary inspections. The identification and description of alien fungi potentially pathogenic to native European flora before their introduction in Europe, is a paramount need in order to limit the risk of invasion and the impact to forest ecosystems. To determine the potential invasive fungi, a sentinel trees plot was established in Fuyang, China, using healthy seedlings of European tree species including Quercus petreae, Q. suber, and Q. ilex. The fungal assemblage associated with symptomatic specimens was studied using the tag-encoded 454 pyrosequencing of the nuclear ribosomal internal transcribed spacer-1 (ITS 1). Taxa with probable Asiatic origin were identified and included plant pathogenic genera. These results indicate that sentinel plants may be a strategic tool to improve the prevention of bioinvasions

Changes in phenolic metabolites of scots-pine phloem induced by Ophiostoma brunneo-ciliatum, a bark-beetle-associated fungus

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