Behaviour 2019
Spatial resolution and optical sensitivity of Indian stingless bee, Tetragonula iridipennis
Asmi Jezeera M1, Pierre Tichit2, Balamurali GS1, Emily Baird3, Almut Kelber2, Hema Somanathan1. 1Indian Institute of Science Education and Research Thiruvananthapuram , Thiruvananthapuram, Kerala, India; 2Lund University, Lund, , Sweden; 3Stockholm University, Stockholm, , Sweden

Foraging bees must discern flowers in the backdrop of complex backgrounds. The acuity of vision in the western honeybee, Apis mellifera, and the bumblebee, Bombus terrestris are well studied. Stingless bees are ubiquitous pollinators in the tropics; however, little is known about their vision and visual behavior. T.iridipennis (inter-tegular span (its) = 1.1450.08 mm) is much smaller than honeybees (its > 2mm) and has correspondingly small eyes. We estimated the theoretical spatial resolution and optical sensitivity of the Indian stingless bee, Tetragonula iridipennis using anatomical methods and MicroCT. The acceptance angle was theoretically estimated in T. iridipennis. Further, optical sensitivity and the eye parameter were calculated. We further behaviourally determined the spatial resolution of their vision for single targets in a y-maze apparatus. The detection threshold was estimated for stimuli with only chromatic contrast and for stimuli with both chromatic and achromatic contrast, respectively. Based on estimated values of spatial resolution, optical sensitivity, and eye parameter, we conclude that the eyes of T.iridipennis are optimized for optical sensitivity.