Impact of odorants on perception of sweetness by honey bees

• Published in: PloS one Vol. 18; no. 12; p. e0290129
• Main Authors: Pel, Allyson V., Van Nest, Byron N., Hathaway, Stephanie R., Fahrbach, Susan E.
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 27.12.2023
• Subjects: Allelochemicals; Apis mellifera; Aroma compounds; Assaying; Bees; Biology and Life Sciences; Blueberries; Flowering; Flowering plants; Flowers; Flowers & plants; Food; Foraging behavior; Honey; Honeybee; Human subjects; Hypotheses; Laboratory animals; Laboratory tests; Limonene; Linalool; Low concentrations; Nectar; Odorants; Perception; Perceptions; Physical Sciences; Plant nectar; Plants (botany); Pollinators; Proboscis; Properties; Social Sciences; Strawberries; Sucrose; Sugar; Sweetness; Volatiles; United States; North Carolina; St Louis Missouri; United States > US
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0290129

Organic volatiles produced by fruits can result in overestimation of sweetness by humans, but it is unknown if a comparable phenomenon occurs in other species. Honey bees collect nectar of varying sweetness at different flowering plants. Bees discriminate sugar concentration and generally prefer higher concentrations; they encounter floral volatiles as they collect nectar, suggesting that they, like humans, could be susceptible to sweetness enhancement by odorant. In this study, limonene, linalool, geraniol, and 6-methyl-5-hepten-2-ol were tested for their ability to alter behaviors related to perception of sweetness by honey bees. Honey bees were tested in the laboratory using proboscis extension response-based assays and in the field using feeder-based assays. In the laboratory assays, 6-methyl-5-hepten-2-ol and geraniol, but neither linalool nor limonene, significantly increased responses to low concentrations of sucrose compared with no odorant conditions in 15-day and 25-day-old adult worker honey bees, but not in 35-day-old bees. Limonene reduced responding in 15-day-old bees, but not in the older bees. There was no odorant-based difference in performance in field assays comparing geraniol and limonene with a no odorant control. The interaction of the tested plant volatiles with sucrose concentration revealed in laboratory testing is therefore unlikely to be a major determinant of nectar choice by honey bees foraging under natural conditions. Because geraniol is a component of honey bee Nasonov gland pheromone as well as a floral volatile, its impact on responses in the laboratory may reflect conveyance of different information than the other odorants tested.