The distraction function of extrafloral nectaries: keeping ants away from flowers and preventing interaction with pollinators

Abstract

Ants protect plants from herbivores in exchange for extrafloral nectar, but they can also disrupt pollination by visiting flowers and deterring pollinators, thereby reducing plant fitness. The Distraction Hypothesis suggests that extrafloral nectaries (EFNs) attract ants away from flowers to mitigate pollination disruption. In the present study, we tested this hypothesis by conducting an ant exclusion experiment in Ferocactus recurvus to evaluate the impact of ants on plant fecundity (seed production). Ant presence in flowers was associated with reduced seed production and overall plant fecundity, as flowers visited by ants produced fewer seeds and were smaller in size compared to ant-excluded flowers. According to the hypothesis, an increased number of EFNs was associated with a lower likelihood of ants visiting the flowers. Ferocactus recurvus plants produces EFNs with high-sucrose nectar for plant defense and to reduce conflicts between ants and pollinators. Plant width was positively correlated with the number of EFNs and flowers, and there was an optimal number of EFNs that attracted a higher number of ants, thereby keeping them away from flowers. Overall, our findings highlight the complex and dynamic nature of interactions between plants, ants, and pollinators, and the potential trade-offs that exist between ant protection and pollinator attraction. Our findings suggest that while ants can protect plants, their presence can also negatively impact plant reproduction, and EFNs play a key role in managing this balance by reducing conflicts between ants and pollinators.