Behaviour 2019
Black on white: an exploration of the visual factors influencing the shimmering response in Apis dorsata
Sajesh Vijayan, Hema Somanathan. IISER Thiruvananthapuram, Thiruvananthapuram, Kerala, India

Due to the absence of physical barriers, open nesting species of honey bees such as Apis dorsata and Apis florea require specialised defence mechanisms against predators. Shimmering response is one such behaviour and is characterised by a travelling wave on the bee curtain. Shimmering is generated by bees flipping their abdomen in a coordinated manner, and previous studies have shown that predators and intruders such as hornets can induce shimmering, which in turn affects the flight trajectory of the intruding organisms and prevent them from approaching too close to the bee curtain. Studies have also shown that during shimmering, the comb itself vibrates, and there is an increased production of Nasonov pheromone by the surface bees. In this study, we explore the effect of contrast of an object with respect to the background as well as the size of the stimulus on initiating a shimmering response. We found that A. dorsata only responded to the darkest stimuli against a light background and the largest stimulus also elicited the strongest response from the honey bees. We discuss the potential reasons behind this conditional response to moving objects by the giant honey bees.