Specific wavelengths of light modulate honey bee locomotor activity

Light plays a crucial role in honey bee (Apis mellifera) behavior by influencing foraging, navigation, and locomotor activity (LMA). While the effects of light on LMA have been previously documented, the specific roles of different wavelengths have remained unknown. In this study, we investigated how exposure to specific infrared (IR, 849 nm), green (528 nm), blue (447 nm), and ultraviolet (UV, 372 nm) wavelengths, as well as their combinations, affected LMA. Specifically, using a custom-built illumination setup and the Api-TRACE video tracking system, we monitored and analyzed bee movement in a homogeneously illuminated environment. Our analysis revealed significant differences in LMA depending on the wavelength to which the bees were exposed. This study demonstrated that the green light promoted LMA. On the other hand, UV light suppressed the LMA of honey bees. The suppression was even greater when the UV light was combined with the blue light. Additionally, similarities in activity patterns were examined, and it was found that only-green, only-blue and only-IR conditions produced highly similar daily activity patterns, whereas UV-enriched spectra, particularly blue–UV and blue–green–UV, generated the most distinct temporal profiles. That information can be applied to experimental standardization, the design of flight-room environments, and the management of colonies under artificial illumination.