A Novel Behavioral Assay to Investigate Gustatory Responses of Individual, Freely-moving Bumble Bees (<em>Bombus terrestris</em>)

Abstract

Generalist pollinators like the buff-tailed bumble bee, Bombus terrestris, encounter both nutrients and toxins in the floral nectar they collect from flowering plants. Only a few studies have described the gustatory responses of bees toward toxins in food, and these experiments have mainly used the proboscis extension response on restrained honey bees. Here, a new behavioral assay is presented for measuring the feeding responses of freely-moving, individual worker bumble bees to nutrients and toxins. This assay measures the amount of solution ingested by each bumble bee and identifies how tastants in food influence the microstructure of the feeding behavior.The solutions are presented in a microcapillary tube to individual bumble bees that have been previously starved for 2-4 hr. The behavior is captured on digital video. The fine structure of the feeding behavior is analyzed by continuously scoring the position of the proboscis (mouthparts) from video recordings using event logging software. The position of the proboscis is defined by three different behavioral categories: (1) proboscis is extended and in contact with the solution, (2) proboscis is extended but not in contact with the solution and (3) proboscis is stowed under the head. Furthermore the speed of the proboscis retracting away from the solution is also estimated.In the present assay the volume of solution consumed, the number of feeding bouts, the duration of the feeding bouts and the speed of the proboscis retraction after the first contact is used to evaluate the phagostimulatory or the deterrent activity of the compounds tested.This new taste assay will allow researchers to measure how compounds found in nectar influence the feeding behavior of bees and will also be useful to pollination biologists, toxicologists and neuroethologists studying the bumble bee's taste system.

Use of theAplysiafeeding network to study repetition priming of an episodic behavior

“…In some species the term "microstructure" has been used to describe the patterning of ingestive responses (Fig. 2) (Bowdan 1988;Davis and Smith 1992;Itskov et al 2014;Ma et al 2016;Mendez et al 2016;Stellar and Shrager 1985). For example, when Drosophila feed, what are known as "sips" are organized into "bursts" (Itskov et al 2014).…”

Ovary activation does not correlate with pollen and nectar foraging specialization in the bumblebeeBombus impatiens

“…We used PER here to be consistent with previous studies of A. melifera , but the assay simply does not have the power to detect sensory sensitivity differences in bumblebees that it does in honeybees, where subtle differences in stimuli can be assayed (e.g., Page et al, 2006 ). Our results suggest that there may be differences in sensory sensitivity between pollen specialists and generalist foragers, but other PER methods may better test this hypothesis (e.g., Ma et al, 2016 ; Muth et al, 2017 ; Kapheim & Johnson, 2017 ). Perhaps more direct measures, such as electrophysiological recordings of antennal stimulation, or foraging choice experiments at a range of feeders, could provide a more powerful measure of sensory sensitivity variation in bumblebees.…”

A novel protocol for studying bee cognition in the wild

“…Or, field‐based differential conditioning by FMPER might help ecologists investigate putative cases of floral mimicry, by establishing whether a bee can or cannot discriminate between floral stimuli of interest. Besides basic work on comparative cognition, FMPER's potential for assessing gustatory responsiveness (similar to Ma, Kessler, Simpson, & Wright, ) is relevant to many aspects of bee biology (Scheiner et al., ), including tests of hypotheses relating to the evolution of sociality (e.g. the reproductive ground plan hypothesis: Kapheim & Johnson, ).…”