How to Join a Wave: Decision-Making Processes in Shimmering Behavior of Giant Honeybees (Apis dorsata)

Abstract

Shimmering is a collective defence behaviour in Giant honeybees (Apis dorsata) whereby individual bees flip their abdomen upwards, producing Mexican wave-like patterns on the nest surface. Bucket bridging has been used to explain the spread of information in a chain of members including three testable concepts: first, linearity assumes that individual “agent bees” that participate in the wave will be affected preferentially from the side of wave origin. The directed-trigger hypothesis addresses the coincidence of the individual property of trigger direction with the collective property of wave direction. Second, continuity describes the transfer of information without being stopped, delayed or re-routed. The active-neighbours hypothesis assumes coincidence between the direction of the majority of shimmering-active neighbours and the trigger direction of the agents. Third, the graduality hypothesis refers to the interaction between an agent and her active neighbours, assuming a proportional relationship in the strength of abdomen flipping of the agent and her previously active neighbours. Shimmering waves provoked by dummy wasps were recorded with high-resolution video cameras. Individual bees were identified by 3D-image analysis, and their strength of abdominal flipping was assessed by pixel-based luminance changes in sequential frames. For each agent, the directedness of wave propagation was based on wave direction, trigger direction, and the direction of the majority of shimmering-active neighbours. The data supported the bucket bridging hypothesis, but only for a small proportion of agents: linearity was confirmed for 2.5%, continuity for 11.3% and graduality for 0.4% of surface bees (but in 2.6% of those agents with high wave-strength levels). The complimentary part of 90% of surface bees did not conform to bucket bridging. This fuzziness is discussed in terms of self-organisation and evolutionary adaptedness in Giant honeybee colonies to respond to rapidly changing threats such as predatory wasps scanning in front of the nest.

Agonistic interactions between the honeybee (Apis mellifera ligustica) and the European wasp (Vespula germanica) reveal context-dependent defense strategies

“…This behavior has been observed in the giant honeybee ( Apis dorsata ) [34,35], the dwarf honeybee ( Apis florea ) [5], A . cerana [36], A .…”

Social waves in giant honeybees (Apis dorsata) elicit nest vibrations

“…1; Kastberger et al 2011a, b, 2012, 2013). It was suspended beneath a horizontal wire fixed above the nest attached by a flexible thread, allowing the dummy to swing.…”

“…They nest in the open (Seeley et al 1982) and are, therefore, especially exposed to predators, such as mammals (Kastberger 1999), birds (Seeley et al 1982; Kastberger and Sharma 2000) and wasps (Seeley et al 1982; Kastberger et al 2008, 2010). Their most prominent defensive behaviour against such threats is shimmering, which generates repetitive social waves with anti-predatory impact (Kastberger et al 2008, 2010, 2012, 2013; Weihmann et al 2012). In shimmering, bees at the nest surface, predominantly younger cohorts (Lerchbacher et al, submitted) in the quiescent regions peripheral to the mouth zone (Kastberger et al 2011b), show simultaneous and cascaded actions (Schmelzer and Kastberger 2009) whereby their abdomens are flipped upwards at an angle between 20° and 120° (Kastberger et al 2011a, b).…”

“…However, two mechanistic viewpoints can here be proposed:

First, mechanical cues provoked by shimmering may be important for the rapidness of the wave propagation across the nest. Alternative strategies eventually processed by visual cues among adjacent neighbours, utilising stigmergic (Grasse 1959; Kastberger et al 2013) principles, such as bucket-bridging (Kastberger et al 2012) or eavesdropping (Peake 2005; Jones et al 2011), would be much slower by one or two orders of magnitude than those which are actually observed in shimmering (Kastberger et al 2012, 2013). The saltatoric principle of wave propagation (Kastberger et al 2013), which may speed up the wave from a basically bucket-bridging process by a factor of 3, is supposed to be associated to the visual input of threatening cues and to the mechanical effects of the shimmering waves in the bee curtain.

Second, shimmering could benefit the entirety of the colony by allowing colony-intrinsic propagation of information across the nest via its mechanical expression of wave components (Kastberger et al 2011b).

…”

“…Alternative strategies eventually processed by visual cues among adjacent neighbours, utilising stigmergic (Grasse 1959; Kastberger et al 2013) principles, such as bucket-bridging (Kastberger et al 2012) or eavesdropping (Peake 2005; Jones et al 2011), would be much slower by one or two orders of magnitude than those which are actually observed in shimmering (Kastberger et al 2012, 2013). The saltatoric principle of wave propagation (Kastberger et al 2013), which may speed up the wave from a basically bucket-bridging process by a factor of 3, is supposed to be associated to the visual input of threatening cues and to the mechanical effects of the shimmering waves in the bee curtain.…”