Dim-light colour vision in the facultatively nocturnal Asian giant honeybee, Apis dorsata

Abstract

We discovered nocturnal colour vision in the Asian giant honeybee Apis dorsata— a facultatively nocturnal species — at mesopic light intensities, down to half-moon light levels (approx. 10 −2 cd m −2 ). The visual threshold of nocturnality aligns with their reported nocturnal activity down to the same light levels. Nocturnal colour vision in A. dorsata is interesting because, despite being primarily diurnal, its colour vision capabilities extend into dim light, while the ‘model’ European honeybee Apis mellifera is reported to be colour-blind at twilight. By employing behavioural experiments with naturally nesting A. dorsata colonies, we show discrimination of the trained colour from other stimuli during the day, and significantly, even at night. Nocturnal colour vision in bees has so far only been reported in the obligately nocturnal carpenter bee Xylocopa tranquebarica. The discovery of colour vision in these two bee species, despite differences in the extent of their nocturnality and the limitations of their apposition compound eye optics, opens avenues for future studies on visual adaptations for dim-light colour vision, their role in pollination of flowers at night, and the effect of light pollution on nocturnal activity in A. dorsata, a ubiquitous pollinator in natural, agricultural and urban habitats in the Asian tropics and sub-tropics.

MoonShine: A software‐hardware system for simulating moonlight ground illuminance and re‐creating artificial moonlight cycles in a laboratory environment

“…Most nocturnally active animals are currently thought to have achromatic vision mediated by a single rod opsin with a peak absorbance near 500 nm, similar to the spectral sensitivity of human scotopic vision (Cronin et al, 2014;Hauser & Chang, 2017). Nonetheless, dim-light nocturnal colour vision has been reported in some nocturnal hawkmoth species and two bee species, as well as in a species of frog, toad, and gecko (Kelber & Roth, 2006;Vijayan et al, 2023;Warrant & Somanathan, 2022). These discoveries suggest that colour vision in nocturnal animals may be more widespread than previously assumed, especially in insects.…”

Looking across the gap: Understanding the evolution of eyes and vision among insects

“…Indeed, some insects such as giant hawkmoths (reviewed in ref. [60]) and the Asian giant honeybee Apis dorsata [65] even have color vision at night. The broad patterns of the evolution of the major insect eye types and how they impact vision and may underlie adaptations are reasonably well understood.…”