PLANT-ARTHROPOD INTERACTIONS IN MOUNTAIN ECOSYSTEMS

The present Ph.D. thesis is organized as a collection of research papers published, submitted, and in preparation. Chapter 1. Here is introduced the knowledge about plant and arthropod interactions in mountain ecosystems and the aims of the Ph.D. project followed by an introduction to the two different study cases of my research. A brief overview of the two Ph.D. side projects is also reported in this chapter. Chapter 2, “Plant-arthropod interactions: the case study of Androsace brevis (Hegetschweiler) Cesati (Primulaceae)”. This chapter focuses on the characterization of flower-visiting arthropod community linked to the alpine plant species Androsace brevis, a narrow-endemic plant of Southern-Central Alps (Italy) characterized by a short (about two weeks) and early (May-June) flowering period. This species is particularly threatened by climate warming. The first study (paragraph 2.1) describes the floral and pollen morphology of A. brevis, which were useful in investigating the pollination biology of this species as well as its possible pollination strategies and vectors. The study reported in paragraph 2.2 focuses on the development and subsequent evaluation of two methodological approaches employed for the study of the flower-visiting arthropod communities of A. brevis: manual sampling and video-observations. Subsequently, a detailed characterization of the A. brevis flower-visiting arthropod community in relation with weather conditions, was carried out selecting two A. brevis populations (Cugn Peak, Como, Lepontine Alps, Italy; Benigni Hut, Bergamo, Orobic Alps, Italy) (paragraph 2.3). In paragraph 2.4, the pollen grains retrieved from A. brevis flower-visiting arthropod collected at Benigni Hut for three consecutive years have been analysed from both qualitative and quantitative point of view by light microscopy. Palynological analysis allowed to identify the pollination network that characterize the high-altitude ecosystem during a particular period of the year as the early season (May-June) in alpine environment, when the snow cover still present on the ground and few plants are flowering (work in preparation). Finally, in paragraph 2.5, a specific investigation on the high-altitude communities of Braconidae (Hymenoptera) was carried out for the same two sites previously reported, resulting in the discovery of four new species of Braconidae for the Italian fauna. Additionally, this study reports the first record of the alien species Lysiphlebus testaceipes (Cresson, 1880) in an Alpine context. Chapter 3, “Plant and flower-visiting arthropod communities within the Stelvio National Park”. This study applied the two methodological approaches developed with the previous project to a broader context. The study was conducted in the Martello Valley (Bolzano province, South Tyrol, Italy) within the Stelvio National Park. The effects of the altitudinal gradient (from 900 to 2700 m asl) and the different type of land management (from the natural grasslands to the apple orchards) were investigated on the flower-visiting arthropod abundance and community composition (paragraph 3.1, in preparation). Moreover, a molecular approach (ITS2 metabarcoding) has been developed as an alternative to the traditional palynological analysis conducted by light microscopy (paragraph 3.2, submitted). Chapter 4, “Ph.D. Side projects”. In this chapter, a new plant species (Campanula bergomensis, Campanulaceae) and a new insect species (Oreonebria tresignore, Carabidae) for Orobic Alps (Bergamo, Northen Italy) are characterized both morphologically and genetically (paragraphs 4.1, 4.2). Chapter 5, “Conclusions and future prospects” of the research. Chapter 6, “Ph.D. Activities”. Here is presented the activities carried out during my Ph.D., comprehensive of all the papers published, submitted, in preparation, and future papers on data collected for the Ph.D. project; all the congresses and seminaries; teaching activities and participation in projects.