Generalization of Foraging Experience Biases Bees Toward Flowers With Complex Morphologies

Abstract

The importance of pollinators as selective agents for many floral traits is well established, but understanding their role in the evolution of complex floral shapes remains challenging. This is because pollinators often need much practice to efficiently handle morphologically complex flowers and extract their food rewards. What induces foragers to persistently visit and pollinate complex flowers despite their initial low profitability? We previously found that naive bumblebees, and unsuccessful feeding attempts of experienced ones, contribute to the pollination of complex flowers. Here we tested a complementary hypothesis, positing that successful foraging on flowers of one complex shape prepares pollinators to visit other species of different complex morphologies. We trained bumblebees to computer-controlled artificial flowers that were either simple, complex or both simple and complex. We then recorded their feeding choices and handling times on a second array of simple and complex flowers that had different shapes and required another handling technique. Bees trained on a single flower type (whether simple or complex) preferred flowers of the same type in the testing array. The foragers’ preferences after training on both flower types depended on the reward schedule during training: when both flower types rewarded equally, simple flowers were preferred at the test phase; when complex flowers provided higher reward during training, they became the preferred flower type during testing. These results suggest that successful foraging on complex flowers, especially when highly rewarding, can indeed induce insect pollinators to attempt additional flower species with other complex shapes.

Floral Cues and Flower Handling Tactics Affect Switching Decisions by Nectar-Foraging Bumble Bees

“…Furthermore, similarities in motor routines in co-flowering species, alongside the inherent complexity of each motor routine, might also affect bees’ decisions to switch, as bees can transfer motor routines they have learned from one species to another, reducing the cost of learning (Ishii & Kadoya, 2016; Krishna & Keasar, 2021; Richman et al, 2021).…”

The Role of Similarity of Stimuli and Responses in Learning by Nectar-Foraging Bumble Bees: A Test of Osgood’s Model

“…These include serial reversal learning (Mota & Giurfa, 2010;Strang & Sherry, 2014), navigation (Cheng, 2005;Cheng & Wignall, 2006), learning the cue that indicates nectar (Dukas, 1995), nest (Colborn et al, 1999;Fauria et al, 2002;Worden et al, 2005), or oviposition site (Weiss & Papaj, 2003). Much research on transfer and interference has focused on learning how to handle flowers to get nectar rewards (Chittka & Thomson, 1997;Gegear & Laverty, 1998;Goulson et al, 1997;Krishna & Keasar, 2021;Laverty, 1994aLaverty, , 1994bLewis, 1986;Lichtenberg et al, 2020;Raine & Chittka, 2007;Woodward & Laverty, 1992).…”

“…Bumble bees use a variety of flowers in the wild and associate traits of those flowers (e.g., colour, scent, pattern or shape) with rewards such as nectar (Clarke et al, 2013;Dyer et al, 2006;Giurfa et al, 1996;Gumbert, 2000;Whitney et al, 2009;Wright & Schiestl, 2009). Accessing nectar from flowers require different motor routines depending on flower morphology (Krishna & Keasar, 2021;Laverty, 1994b).…”

“…Bumble bees use a variety of flowers in the wild and associate traits of those flowers (e.g., colour, scent, pattern or shape) with rewards such as nectar (Clarke et al, 2013; Dyer et al, 2006; Giurfa et al, 1996; Gumbert, 2000; Whitney et al, 2009; Wright & Schiestl, 2009). Accessing nectar from flowers require different motor routines depending on flower morphology (Krishna & Keasar, 2021; Laverty, 1994b). Individual bumble bees can learn how to handle more than two types of flowers that require different handling techniques (Chittka & Thomson, 1997; Gegear & Laverty, 1998; Ishii & Kadoya, 2016; Krishna & Keasar, 2019; Woodward & Laverty, 1992).…”

Can sociality facilitate learning of complex tasks? Lessons from bees and flowers

“…Bumblebees show a mild but persistent innate preference for complex flowers over simplified ones in flight-room experiments. Early training on complex artificial flowers, especially if paired with high reward, improves their learning of a second complex morphology that requires a different handling technique [ 29 ]. These findings suggest behavioural mechanisms that help overcome the initial learning costs of handling complex flowers.…”