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Trabajo presentado en Estocolmo (Suecia) entre el 29 de junio y el 3 de julio de 2015., Only in Sweden 360 million conifer seedlings are planted each year but a substantial proportion of these are killed by pine weevils (Hylobius abietis) and black spruce beetles (Hylastes cunicularius). A high survival rate is essential for a high primary production of forest raw materials and biomass. There is currently no suitable non-insecticide plant protection option for a large part of these seedlings. One option may, however, be to trigger the seedlings´ own induced defense by treating them with a plant activator at the nursery so that they are prepared when they later becomes attacked by pine weevils in the field. The induced defense is under natural conditions generally expressed after damage by, e.g. a pest insect, whereas constitutive defenses are permanently present. Constitutive defenses serves to inhibit an initial attack whereas the induced defense serves to actively and vigorously stop the attack. The induced defense is powerful but the time lag after an initial attack before the induced defenses are fully expressed may be detrimental for a plant when the pest pressure is high. This weakness of the induced defense can be circumvented by applying a plant activator to trigger the induced defense of the plant before it is exposed to attacks. There is a suitable plant activator to trigger the induced defense of conifers available. That is methyl jasmonate which is a substance that also is produced naturally when a plant is attacked. It triggers the production of traumatic resin channels and different types of chemical defense substances. In this talk I will present some recent results related to the potential of this method to protect conifer seedlings against pine weevils.

Comunicación presentada en la Reunión celebrada en la ETSI Montes, Forestal y del Medio Natural de la Universidad Politécnica de Madrid, el día 8 de octubre de 2015. Pine trees are long -lived, widespread organisms that have to cope with multiple biotic stresses during their life cycle. To face against biological aggressions pine trees harbour terpenoids and phenolics as major chemical defences that may avoid or deter the attack providing resistance. Mono and sesquiterpenes, the volatile fraction of oleoresin, have been found to be adaptive resistance traits and to differ between and within species. However much less attention has been paid to sources of phenotypic variation in diterpenes, the non- volatile fraction of oleoresin that seals the stem wounds after oxidization. We examined the induced defensive responses of the diterpene fraction in two pine species, one native (Maritime pine) and one exotic (Monterey pine) to Europe, against two native insect herbivores, the bark chewing pine weevil and the pine processionary caterpillar; and explored the association between the induced chemical profile of diterpenes in each species and the subsequent damage. We found that the two pine species showed different constitutive and induced diterpene concentration in stem and needles. Whereas Pinus pinaster increased total di terpene concentration only in the stem against the two herbivores, P. radiata diterpene defences were locally induced in the damaged tissue due to herbivore feeding activity. Regarding to the chemical diterpene profile, the native P. pinaster produced a ge neral induced response increasing diterpene concentration against the two herbivores in the stem, whereas the exotic P. radiata showed a weevil -induced increase and a caterpillar -induced decrease in the most abundant diterpenes in the needles.

Póster presentado en Estocolmo (Suecia) entre el 29 de junio y el 3 de julio de 2015. Following an herbivore attack plants can reduce damage by inducing a wide variety of highly specific chemical and physical defences. Plants are able to recognize, integrate and respond accordingly in a specific manner to the biotic stimuli provoked by different herbivore species. This specificity of induced defences is particularly important for long-lived plants (e.g. pines) which have to face against multiple biological aggressions during their life cycle. In this sense, it has been recently documented that induction of mono- and sesquiterpenes (the volatile fraction of oleoresin) in pine trees is specific to plant species, herbivore identity and plant tissue. However, much less attention has been paid to understand the sources of phenotypic variation of diterpenes, the non-volatile fraction of oleoresin that seals the wounds after oxidization.