Fatal attraction - the predation of pollinators leads to reproductive conflict in pollen limited populations of Drosera hookeri (Droseraceae) - Dataset

Abstract

Pollinator-prey conflict in carnivorous plants occurs when plants that benefit from pollinators are pollen-limited and pollinators are snared by trap-leaves. To date a strong pollinator-prey conflict has not been found and is attributed to spatial and/or cue differences between flowers and traps abating conflict. Here we test whether pollinator-prey conflict occurs for Drosera hookeri (Droseraceae), which produces entomophilous flowers adjacent to leaf-traps. We also test the hypothesis that flowers have a dual role of pollinator attraction and deception by tumbling pollinators and other floral visitors into leaf-traps. From 2007-2021, in a drought-prone habitat in eastern Australia, pollinator diversity and visitation rates were scored at flowers using camcorders while pan-traps provided an estimate of pollinator abundance in the community. Hand-pollination experiments were used to determine pollinator dependence and pollen limitation. We also measured arthropod abundance in trap-leaves before, during and after flowering. In a paired experiment we compared leaf captures between plants with and without flowers to determine if flowers are complicit in the leaf captures of pollinators. Although self-compatible, with a delayed selfing-mechanism, outcrossed flowers produced more seed than self-pollinated flowers, indicating that pollinators are beneficial. Plants were pollen-limited in both years tested. Flies (non-pollinating and pollinating) were the most common prey with the greatest numbers during peak flowering. Pollinators, predominantly Melangyna virdiceps (Syriphidae, Diptera), contributed c. 57% of prey captures, and experimentally we show that they are not attracted to plants without flowers. Pollinators are often deposited into trap-leaves from flowers, which tip under their weight, to nearby leaf traps. A strong pollinator-prey conflict was detected with an overlap in prey and pollinators in a pollen and pollinator-limited system. Flowers attract pollinators and non-pollinators to plants. Leaf entrapment for pollinators occurs as a mishap in foraging rather than attraction to trap-leaves. The flowers in D. hookeri have the dual role of pollination and prey provision.