In Giant Honey Bees, abdomen flipping happens in a variety of contexts. It can be either synchronous or cascaded, such as in the collective defense traits of shimmering and rearing-up, or it can happen as single-agent behavior. Abdomen flipping is also involved in flickering behavior, which occurs regularly under quiescent colony state displaying singular or collective traits, with stochastic, and (semi-) synchronized properties. It presumably acts via visual, mechanoceptive, and pheromonal pathways and its goals are still unknown. This study questions whether flickering is preliminary to shimmering which is subject of the fs (flickering-shimmering)-transition hypothesis? We tested the respective prediction that trigger sites (ts) at the nest surface (where shimmering waves had been generated) show higher flickering activity than the alternative non-trigger sites (nts). We measured the flickering activity of ts- and nts-surface bees from two experimental nests, before and after the colony had been aroused by a dummy wasp. Arousal increased rate and intensity of the flickering activity of both ts- and nts cohorts (P < 0.05), whereby the flickering intensity of ts-bees were higher than that of nts-bees (P < 0.05). Under arousal, the colonies also increased the number of flickering-active ts- and nts-cohorts (P < 0.05). This provides evidence that cohorts which are specialist at launching shimmering waves are found across the quiescent nest zone. It also proves that arousal may reinforce the responsiveness of quiescent curtain bees for participating in shimmering, practically by recruiting additional trigger site bees for expanding repetition of rate and intensity of shimmering waves. This finding confirms the fs-transition hypothesis and constitutes evidence that flickering is part of a basal colony-intrinsic information system. Furthermore, the findings disprove that the muscle activity associated with flickering would heat up the surface bees. Hence, surface bees are not actively contributing to thermoregulation.
Keywords: Apis dorsata; Giant Honey Bee; communication; flickering behavior; flickering-shimmering transition hypothesis; recruitment for defense; social insects.