Plants and flower-visiting arthropods in mountain ecosystems : the case study of the alpine species Androsace brevis (Primulaceae)

Climate change is expected to strongly modify fundamental plant-pollination networks of high-mountain ecosystems, but very little is still known about this topic. We investigated the complex interactions between flower-visiting arthropods and plants on Alps using Androsace brevis as model species, a narrow endemic plant which flowers in early season, immediately after snowmelt, when few trophic resources are available for those few active arthropods. We worked in Lepontine Alps (Como. Italy) and Orobic Alps (Bergamo, Italy) using an integrated approach involving manual sampling and in-field video observations of A. brevis flowers-visiting arthropods. These approaches allowed to obtain both an accurate identification of A. brevis flower-visiting arthropods and a characterization of their behavior, revealing variability among taxa and allowing to hypothesize their ecological roles. In particular, manual sampling method allowed to identify early-season active arthropods at low taxonomic level and to determine which taxa actually can pollinate A. brevis by quali-quantitative palynological analysis of pollen carried by sampled flower-visiting arthropods.In four years of manual sampling, we sampled specimens belonging to 10 orders and to 50 families. Diptera Anthomyiidae and Hymenoptera Apoidea turn out to be the main pollinators of A. brevis as well as the taxa at the base of high-mountain plant-pollinator networks. Our results give insight into early-season plant-pollinator interactions in the Alps, which represent a fundamental component of high-mountain ecosystems, strongly threatened by climate change. Manual sampling, together with videorecording method, could allow to develop conservation plans for ecological networks in high-mountain ecosystems.