Florivory and pollinator visitation: a cautionary tale.

Kaoru Tsuji,Carolyn P Rice,Tadashi Fukami,Manpreet K Dhami,David J.R Cross,Nic H Romano

doi:10.1093/aobpla/plw036

Abstract

Florivory, or damage to flowers by herbivores, can make flowers less attractive to pollinators, potentially resulting in reduced plant fitness. However, not many studies have combined observations with experiments to assess the causal link between florivory and pollination. We conducted field observations at eight sites in northern California, combined with field experiments that involved artificial floral damage, to study the effect of florivory on pollination in the hummingbird-pollinated sticky monkeyflower, Mimulus aurantiacus We used two indicators of pollinator visitation, stigma closure and the presence of microorganisms in floral nectar. The field observations revealed that stigma closure was less frequent in damaged flowers than in intact flowers. In the experiments, however, floral damage did not decrease stigma closure or microbial detection in nectar. Instead, neighbouring flowers were similar for both indicators. These results suggest that the observed negative association between florivory and pollination is not causal and that the location of flowers is more important to pollinator visitation than florivory in these populations of M. aurantiacus.

Highlights

Floral herbivory can be as widespread as foliar herbivory, but its potential effects on plant fitness have only recently begun to be investigated (McCall and Irwin 2006; Maldonado et al 2015)
We recorded the extent of floral damage for each flower we observed, but we did not find any significant effect of the floral damage extent on pollination, so we focused on the presence or the absence of damage in the analyses presented in this paper
In M. aurantiacus, we have previously found that yeasts appeared more dependent on hummingbirds for nectar colonization than bacteria (Belisle et al 2012)

Summary

Introduction

Floral herbivory can be as widespread as foliar herbivory, but its potential effects on plant fitness have only recently begun to be investigated (McCall and Irwin 2006; Maldonado et al 2015). An increasing number of studies suggest that floral damage can decrease pollinator visitation Resulting in reduced pollination and plant fitness Studies on florivory have often used either field observations or experiments, not both (but see examples of using both in McCall 2008, 2010).

Methods

Results

Discussion

Conclusion