Foraging behavior and pollination efficiency of generalist floral visitors of Leucas aspera (Willd.) link (Lamiaceae)

Abstract

Pollination services from insects are important for the reproductive success of flowering plants. Measuring the effectiveness of floral visitors provide relative contributions of different insect taxa to pollination services. Here, we tested the efficiency of pollinators visiting flowers of Leucas aspera based on single-visit pollen deposition and visitation frequency. We monitored the visitation behaviors of different insects during the peak flowering seasons. We observed a total of 23 insect taxa representing three orders and eight families, among them 18 floral visitors deposited a significant proportion of pollen grains on the stigma. The flower handling time was significantly higher for most butterfly species relative to bees and flies. The number of flowers and inflorescences visited during each foraging bout varied significantly among pollinators. The proportion of conspecific and heterospecific pollen deposited on the stigma varied significantly among floral visitors. L. aspera was not pollen-limited, and the presence of fruit and seed sets in the pollinator exclusion treatments indicated a self-compatible breeding system. Overall, the findings suggested that the different flower visitors of L. aspera provide complementary pollination services and highlight the importance of having diverse communities of pollinators to ensure successful pollination and reproductive success.