Low Strength Magnetic Fields Serve as a Cue for Foraging Honey Bees but Prior Experience is More Indicative of Choice

Abstract

Species of migrating insects use magnetic fields as a navigational tool that is independent of current weather conditions and non-migrating species have been shown to discriminate anomalies in magnetic field from the earth's baseline. Honey bee discrimination of magnetic field has been studied in the context of associative learning, physiology, and whole hive responses. This article uses a combination of free-flight and laboratory studies to determine how small fluctuations from Earth's magnetic field affect honey bee (Apis mellifera L.) decision-making. Honey bees were tested in three experiments: (i) recruitment to an aqueous sucrose feeder, (ii) an artificial free-flight flower patch with floral color-dependent magnetic field strength, and (iii) a Y-maze with alternating colors on a stronger magnetic field. In free-flying feeder experiments, magnetic field served as a temporary cue, but when offered an equal caloric alternative with lesser magnetic field, the latter was preferred. Flower patch experiments showed initial color biases that were abandoned as a response to magnetic field induction. In laboratory experiments, bees showed a color-dependent behavioral response to the magnetic field. The results of this study indicate that bees may use small fluctuations in magnetic fields as a cue but that it is likely low-value as compared with other stimuli. Bioelectromagnetics. 2020;41:458-470. © 2020 Bioelectromagnetics Society.