Pollination in Silene migjornensis, a therophyte endemic to the southern dunes of Mallorca

Abstract

[eng] Silene migjornensis is a plant species restricted to a unique location in the south of Mallorca (Western Mediterranean Basin). Its reproductive biology remains unknown, although its floral syndromes points at nocturnal pollination by lepidopterans. This study aims to present first data regarding to its pollinators such as their taxonomic identification, pollinator efficacy and pollinator fidelity. Also, a literature review of pollination in other species of the genera was performed. Several surveys at night were conducted along the flowering period, and potential pollinators were captured both directly on the flowers and using light traps. Also, pollinator censuses were performed by counting the number and identity of floral visitors in groups of 100 flowers every two hours at nighttime. A total of 92 specimens were captured directly on the flowers and 118 by the light trap, and then the pollen load was analysed to obtain the pollinator efficacy (no. of pollen grains of S. migjornensis) and pollinator fidelity (percentage of pollen grains of S. migjornensis from the total pollen load). Floral visitors of S.migjornensis include moths, spiders, harvestmen, beetles, cockroaches and bugs, though the frequency of visits is generally very low. The harvestmen (Phalangium clavipus) was the most frequent floral visitor in the surveys. However, the efficacy of the pollinators groups is not clear, beetles (Coleoptera) are more effective pollinators than cockroaches (Blattodea) and harvestmen (Opiliones). Overall, the initial hypothesis that S. migjornensis has a pollination specialized towards lepidopterans is not entirely correct, as other pollinators participate to an even greater extent given their visitation rates, a characteristic that others Silene seems to share in the literature review. Finally, this study describes the first case of an endemic harvestman participating in the pollination of a plant species in Mallorca