Acetylcholine and choline in honey bee (Apis mellifera) worker brood food are seasonal and age-dependent

• Published in: Scientific reports Vol. 14; no. 1; pp. 18274 - 12
• Main Authors: Siefert, Paul, Lau, Helene, Leutz, Vivien, Leonhardt, Sara Diana, Schneider, Gaby, Klein, Jochen, Grünewald, Bernd
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 06.08.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 631/136; 631/158; 631/378/3919; 631/443; Acetylcholine; Acetylcholine - analysis; Acetylcholine - metabolism; ACh; Age Factors; Amino acids; Animals; Apis mellifera; Bees; Bees - metabolism; Bees - physiology; Brood food; Choline; Choline - analysis; Choline - metabolism; Colonies; Environmental conditions; Food; Foraging behavior; Honey; Honey - analysis; Humanities and Social Sciences; Insects; Larva - metabolism; Larval development; Liquid chromatography; multidisciplinary; Nursing; Nutrition; Pharmacy; Precipitation; Science; Science (multidisciplinary); Seasonal variations; Seasonality; Seasons; Winter; Nursing; Nutrition; Brood food; Larval development; ACh; Seasonality
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-024-68650-x

Nursing honeybees produce brood food with millimolar concentrations of acetylcholine (ACh), which is synthesized through head gland secretions mixed with honey stomach contents. While we previously demonstrated the necessity of ACh for proper larval development, the dynamics of ACh levels throughout ontogenesis and their seasonal variations have remained unclear until now. Our HPLC analysis reveals dependencies of choline and ACh levels on larval development days (LDDs), influenced by seasonal (April–September) variations. Median ACh concentrations peak on LDD 2, declining significantly toward cell capping, while choline levels are lowest during the initial LDDs, rising markedly toward cell capping. Seasonal patterns show peak ACh levels from April to June and a low in August, paralleling choline's peak in July and low in August. This seasonality holds consistently across multiple years (2020–2022) and colonies, despite potential variations in colony performance and environmental conditions. Our analysis found no correlation between temperature, sunshine, precipitation, or favourable foraging days and ACh/choline levels, suggesting the involvement of additional factors. These findings underscore the seasonal fluctuation of ACh levels and its potential implications for the genetic programs governing winter bee development.