Relative Contribution of Different Bees in Aster (Callistephus chinensis L.) Pollination

Aims: Many insects visit flowering plants, but it’s important to distinguish between floral visitors and effective pollinators, which is often overlooked. There is no such information available about the pollinators of Aster (Callistephus chinensis), a popular seed-propagated flowering crop in India. This study aims to assess the contribution of different bees to the plant’s reproductive success.

Place and Duration of Study: The study was conducted over two years (2021-22 and 2022-23) at the ICAR-Directorate of Floricultural Research, Pune.

Methodology: Observations were recorded at the 50 per cent flowering stage during peak pollinator activity (11:00-12:00 hrs). To assess the relative significance of frequent bee visitors as pollinators, the pollination importance index (PII) was calculated using four factors: (1) Relative abundance (A), (2) Pollen-carrying capacity (PCC), (3) Host fidelity (F) and (4) Pollinator effectiveness (PE).

Results: The results showed that Apis florea was the predominant pollinator of Aster (57.58%) followed by Apis cerana indica (23.93%). While, the highest pollen-carrying capacity was observed in A. cerana indica (4.68 mg per bee) followed by A. florea (3.88 mg/bee). All species showed complete host fidelity to the aster and observed to contact both the stigma and the anther while foraging on aster. The highest Pollination Importance Value (PIV) and Pollination Importance Index (PII) was recorded for A. florea (223.31, 64.77%, respectively) followed by A. cerana indica (111.92, 32.44%, respectively). While other species show comparatively lesser values.

Conclusion: The PIV and PII indicated that A. florea was the most efficient pollinator of Aster compared to A. cerana indica. Other pollinators also contributed to Aster pollination but in lesser extent. Therefore it is also necessary to conserve other pollinators along with honey bees. These findings provide valuable insights for optimizing pollination management in commercial Aster cultivation, promoting the use of effective pollinator species to improve crop yields.