Abstract:

Aims: Specialized pollination systems are often perceived as finely tuned interactions between specific plant species and their pollinators. However, empirical evidence suggests that these systems also accommodate visits from non-pollinating species. While previous research has primarily focused on the mutualistic aspects of plants and pollinators in the specialized pollination, the broader impacts of various floral visitors have been overlooked. The intricate pollination dynamics between Alocasia odora and Colocasiomyia species, notably C. alocasia or C. xenalocasiae, exemplify such specialization. Yet, the roles and influences of numerous other floral visitors remain incompletely understood within this pollination system.
Methods: The specialized pollination system of A. odora served as the focal point of this study. Initially, morphological characteristics of the inflorescence were meticulously observed and documented across various stages of flowering. These observations provided essential insights into the positioning and timing of visitor and pollinator activity on the inflorescence. Subsequently, the primary breeding systems of A. odora were elucidated through controlled breeding experiments. By thoroughly monitoring visitor behavior and conducting pollination efficiency experiments, we identified visitor groups with a preference for inflorescence visitation and evaluated their impacts on successful pollination. Finally, we conducted a comprehensive analysis to assess the influence of generalized visitors on the specialized pollination system of A. odora.
Results: Our meticulous visitor exclusion experiments unequivocally confirmed the indispensable pollinating role of specific Colocasiomyia species in the pollination of A. odora. Furthermore, analysis of the plant’s breeding system had revealed self-incompatibility in A. odora, attributed to the spatial and temporal separation of male and female reproductive phases. Remarkably, the inflorescence of A. odora exhibited a significant attraction to a diverse array of visitors, encompassing species from the Nitidulidae, Apidae, Staphylinidae, and Tarsonemidae families, totaling 10 distinct species. Despite their presence, these visitors did not exert a significant influence on pollination successes and fruit set rates. However, their activities, such as foraging on pollen and sterile zones, had the potential to undermine pollen or other rewarding resource utility and initiate resource competition with genuine pollinators.
Conclusion: This study illuminates the specialized pollination mutualism system between A. odora and Colocasiomyia species, characterized by specificity, stability, and high efficiency. A. odora demonstrates self-incompatibility, with cross-pollination serving as the primary mode of reproduction. The success of pollination hinges upon pollinators, particularly C. alocasia or C. xenalocasiae, which form intimate mutualist relationships with A. odora. Moreover, in the Haikou area, A. odora and two species of Colocasiomyia flies engage in a unique “two-on-one” pollination system. Looking ahead, future studies investigating similar specialized pollination systems should adopt a holistic approach, considering both plants and all interflower visitors comprehensively. By doing so, researchers can obtain a more objective and comprehensive perspective and results.

Key words: specialized pollination, breeding system, floral visitor, pollinator, Araceae, Alocasia odora, Colocasiomyia