Assessment of pollen rewards by foraging bees

Abstract

Summary1. The removal of pollen by flower-visiting insects is costly to plants, not only in terms of production, but also via lost reproductive potential. Modern angiosperms have evolved various reward strategies to limit these costs, yet many plant species still offer pollen as a sole or major reward for pollinating insects. 2. The benefits plants gain by offering pollen as a reward for pollinating are defined by the behaviour of their pollinators, some of which feed on the pollen at the flower, while others collect pollen to provision offspring. 3. We explore how pollen impacts on the behaviour and foraging decisions of pollen-collecting bees, drawing comparisons with what is known for nectar rewards. This question is of particular interest since foraging bees typically do not eat pollen during collection, meaning the sensory pathways involved in evaluating this resource are not immediately obvious. 4. Previous research has focussed on whether foraging bees can determine the quality of pollen sources offered by different plant species, and attempted to infer the mechanisms underpinning such evaluations, mainly through observations of collection preferences in the field 5. More recently experimental research has started to ask whether pollen itself can mediate the detection of, and learning about, pollen sources and associated floral cues. 6. We review advancements in the understanding of how bees forage for pollen and respond to variation in pollen quality, and discuss future directions for studying how this ancestral floral food reward shapes the behaviour of pollinating insects.

Movers and shakers: Bumble bee foraging behavior shapes the dispersal of microbes among and within flowers

“…However, bees foraged much more vigorously within flowers for pollen than for nectar (A. Russell, personal observation), likely explaining differences in dispersal. Thus, additional to the cost of offering their gametes (pollen) as a reward (Hargreaves et al 2009, Nicholls andHempel de Ibarra 2016), our results suggest that flowering plants offering mainly pollen to pollinators may typically ❖ www.esajournals.org contend with more (or more diverse) epiphytic microbes than plants that offer mainly nectar. Consistent with this, for several dioecious species, male flowers had more (or more diverse) microbes than female flowers (which have no pollen to offer to pollinators; Tsuji andFukami 2018, Wei andAshman 2018).…”

How a generalist bee achieves high efficiency of pollen collection on diverse floral resources

“…Bees probably also use appetitive learning in response to pollen guides, analogous to the role of learning in nectar guide use (Leonard and Papaj 2011), as well as other floral features such as color, pattern and scent. However, studies on instrumental and appetitive learning in pollen foraging are rare, compared to studies of these processes in nectar foraging (Muth et al 2015;Muth et al 2016;Nicholls and Hempel de Ibarra 2016;Russell, Golden, et al 2016;.…”

Moral decisionism and its discontents

“…Or, which is roughly the same, explicit decisionists argue that X is adequately, correctly, or profitably understood and represented using decision/choice concepts; these concepts apply to X . For example, a decisionist tells you how bees “decide which patches of flowers to visit” and “decide whether to dance,” whereas an explicit decisionist tells you why there's nothing wrong with speaking of bees' decisions (Nicholls & de Ibarra, , p. 82; Zhang, Si, & Pahl, , p. 1). A decisionist about morality talks about trolley problems in her presentations, books, and blog posts; an explicit moral decisionist argues that trolley problems are key devices and get to the core of ethics .…”