The Sensory and Cognitive Ecology of Nectar Robbing

Sarah K Richman,Rebecca E Irwin,Daniel R Papaj,Minjung Baek,Judith L Bronstein,Jessica L Barker

doi:10.3389/fevo.2021.698137

Abstract

Animals foraging from flowers must assess their environment and make critical decisions about which patches, plants, and flowers to exploit to obtain limiting resources. The cognitive ecology of plant-pollinator interactions explores not only the complex nature of pollinator foraging behavior and decision making, but also how cognition shapes pollination and plant fitness. Floral visitors sometimes depart from what we think of as typical pollinator behavior and instead exploit floral resources by robbing nectar (bypassing the floral opening and instead consuming nectar through holes or perforations made in floral tissue). The impacts of nectar robbing on plant fitness are well-studied; however, there is considerably less understanding, from the animal’s perspective, about the cognitive processes underlying nectar robbing. Examining nectar robbing from the standpoint of animal cognition is important for understanding the evolution of this behavior and its ecological and evolutionary consequences. In this review, we draw on central concepts of foraging ecology and animal cognition to consider nectar robbing behavior either when individuals use robbing as their only foraging strategy or when they switch between robbing and legitimate foraging. We discuss sensory and cognitive biases, learning, and the role of a variable environment in making decisions about robbing vs. foraging legitimately. We also discuss ways in which an understanding of the cognitive processes involved in nectar robbing can address questions about how plant-robber interactions affect patterns of natural selection and floral evolution. We conclude by highlighting future research directions on the sensory and cognitive ecology of nectar robbing.

Highlights

Plant-pollinator mutualisms involve cooperation by each partner but are rife with conflict as well
Initiating the additional motor action required for primary robbing has been shown to be hastened by exposure to robber holes: in a lab study, primary robbing behavior took less time to initiate for naïve bees that were exposed to artificial holes compared to those that were not, suggesting a role of social transmission in learning nectar robbing motor routines (Leadbeater and Chittka, 2008)
Floral visitors use signals and cues provided by flowers, coupled with information about their foraging environment, to make decisions about which flowers to visit and how to extract their rewards

Summary

Introduction

Plant-pollinator mutualisms involve cooperation by each partner but are rife with conflict as well. If nectar robbing is easier to learn or affected less by working memory capacity than foraging legitimately, robbers will tend to switch more between plant species. It is not currently known whether nectar robbing differs from legitimate visitation in terms of how individuals express innate preferences for floral traits, or whether sensory biases (for color, odor, etc.) drive their foraging behavior in the same way.

Results

Conclusion