Manual Sampling and Video Observations: An Integrated Approach to Studying Flower-Visiting Arthropods in High-Mountain Environments

SIMPLE SUMMARY: Our study compared two different methods to identify the arthropods visiting the flowers of the vulnerable endemic alpine species Androsace brevis (Primulaceae) and investigate their behavior. Using the traditional method of manual sampling we could taxonomically identify visiting arthropods on a fine scale and determine which taxa carry pollen. Conversely, video observations provided information on arthropod behavior and activity. By integrating the results obtained from these two approaches, we estimated the diversity of A. brevis flower-visiting arthropods and evaluated which taxa could be involved in its pollination. Our results, in addition to providing new insights on flowering plant–arthropod interactions in early season in the Alps, might be useful in developing effective methods of studying the ecological relationships in high-mountain ecosystems. ABSTRACT: Despite the rising interest in biotic interactions in mountain ecosystems, little is known about high-altitude flower-visiting arthropods. In particular, since the research in these environment can be limited or undermined by harsh conditions and logistical difficulties, it is mandatory to develop effective approaches that maximize possibilities to gather high-quality data. Here we compared two different methods, manual sampling and video observations, to investigate the interactions between the high-mountain arthropod community and flowers of Androsace brevis (Primulaceae), a vulnerable endemic alpine species with a short flowering period occurring in early season. We manually sampled flower-visiting arthropods according to the timed-observations method and recorded their activity on video. We assessed differences and effectiveness of the two approaches to estimate flower-visiting arthropod diversity and to identify potential taxa involved in A. brevis pollination. Both methods proved to be effective and comparable in describing the diversity of flower visitors at a high taxonomic level. However, with manual sampling we were able to obtain a fine taxonomic resolution for sampled arthropods and to evaluate which taxa actually carry A. brevis pollen, while video observations were less invasive and allowed us to assess arthropod behavior and to spot rare taxa. By combining the data obtained with these two approaches we could accurately identify flower-visiting arthropods, characterize their behavior, and hypothesize a role of Hymenoptera Apoidea and Diptera Brachycera in A. brevis pollination. Therefore, we propose integrating the two approaches as a powerful instrument to unravel interactions between flowering plants and associated fauna that can provide crucial information for the conservation of vulnerable environments such as high-mountain ecosystems.