Video analysis as an innovative approach to investigate plant-arthropod interactions in high mountain environments: the case study of Androsace brevis (Primulaceae)

Background and Aims – Little is known about the interactions between arthropods and plants in high altitude environments. However, these interactions are a fundamental component of mountain ecosystems, and may be highly affected by climate change. The use of video observations to investigate arthropod communities is less invasive than manual sampling and allows to study behaviours that may not be identified by field observation. We employed this methodological approach on flower-visiting arthropods of the narrow endemic alpine plant Androsace brevis (Hegetschw.) Ces. as a model of interactions that may be affected by climate change. Methods – We recorded about 87 hours of video in two years during the flowering period of A. brevis (May-June) in two sites of central southern Alps (Lombardy, Italy). During the recording sessions we also registered environmental parameters possibly impacting arthropods’ presence and activity. Subsequently, videos were analysed with a behavioural observation software (BORIS) to investigate the arthropod activity on A. brevis flowers, with a focus on the identification of possible pollinators. Results – The method allowed us to record the activity and time budget of arthropods on flowers. We assessed a high variability in behaviour among taxa, for instance in the mean number of flowers visited, corolla tubes entered, time spent on flowers and in the corolla tube. Moreover, we identified different interactions with the plant. Our results lead us to hypothesize the possible ecological role of flower-visiting arthropods, for instance highlighting the role of Brachycera Diptera and Apoidea Hymenoptera in pollination. Furthermore, we were able to assess correlations between environmental parameters (i.e., temperature, illuminance and wind speed) and arthropods activity in high mountain environments. Conclusions – Our approach has proven to be effective to gain deep insight into the relationships between plants and associated fauna in high mountain ecosystems. In particular, our work represents a contribution towards a better understanding of plant-pollinator interactions in alpine environments.