The recruiter's excitement – features of thoracic vibrations during the honey bee's waggle dance related to food source profitability

Abstract

SUMMARYThe honey beeʼs waggle dance constitutes a remarkable example of an efficient code allowing social exploitation of available feeding sites. In addition to indicating the position (distance, direction) of a food patch, both the occurrence and frequency of the dances depend on the profitability of the exploited resource (sugar concentration, solution flow rate). During the waggle dance, successful foragers generate pulsed thoracic vibrations that putatively serve as a source of different kinds of information for hive bees, who cannot visually decode dances in the darkness of the hive. In the present study, we asked whether these vibrations are a reliable estimator of the excitement of the dancer when food profitability changes in terms of both sugar concentration and solution flow rate. The probability of producing thoracic vibrations as well as several features related to their intensity during the waggle phase (pulse duration, velocity amplitude, duty cycle) increased with both these profitability variables. The number of vibratory pulses, however, was independent of sugar concentration and reward rate exploited. Thus, pulse number could indeed be used by dance followers as reliable information about food source distance, as suggested in previous studies. The variability of the dancerʼs thoracic vibrations in relation to changes in food profitability suggests their role as an indicator of the recruiterʼs motivational state. Hence, the vibrations could make an important contribution to forager reactivation and, consequently, to the organisation of collective foraging processes in honey bees.

Vibratory Communication in Stingless Bees (Meliponini): The Challenge of Interpreting the Signals

“…Thoracic vibrations generated by foragers on their return from a profitable food source are a feature common among eusocial bees, that is the stingless bees (Meliponini), the honeybees (Apini), and the bumblebees (Bombini) (Hrncir et al 2006a(Hrncir et al , 2011. To this day, few species have been studied in some detail.…”

“…To this day, few species have been studied in some detail. Yet, the available data all show that both the occurrence and the temporal pattern of the pulsed vibrations correlate with the profitability of the exploited food source (Meliponini: see above; Apini: A. mellifera ;Esch 1962;Hrncir et al 2011; Bombini: Bombus terrestris; Oeynhausen and Kirchner 2001). So far, it remains an open question whether these similarities in vibratory recruitment communication among eusocial bees derive from a common evolutionary origin or whether they have developed independently in the different bee groups.…”

“…Because in all experimental studies so far sugar solution had been offered ad libitum, this ''excitement threshold'' was determined by the sugar concentration of the collected food. However, the food profitability experienced by a forager and, consequently, her disposition to generate thoracic vibrations, may as well be determined by parameters different from sugar concentration, such as solution flow, handling time, and even the presence of competitors (Hrncir 2009;Hrncir et al 2011) (Fig. 18.4).…”

Standard methods for behavioural studies ofApis mellifera

“…For instance, if the sugar concentration or the solution flow rate (sugar mass per time) change, the dance probability, the dance time and the dance tempo (the number of waggles or reversals per 15 s running on the comb) increase according to the energetic value of the exploited resource (von Frisch, 1967;Farina, 1996;De Marco and Farina, 2001). In the specific case of the waggle dance, the interval between two successive waggle runs (defined as the circle phase) is shorter for higher food source profitability (Seeley et al, 2000;Hrncir et al, 2011). Thus, an enhanced recruitment for higher food source profitability might be explained by a larger number of waggle runs per unit time inside the hive (von Frisch, 1967;Seeley, 1986;Fernández et al, 2003).…”

“…This implies that other stimuli belonging to different sensory modalities are possibly being used. One possible additional source of information used by dance followers are the thoracic vibrations pulsed by the dancer while waggling (frequently referred to as "dance sounds"; Esch, 1961a, b;Wenner, 1962;Hrncir et al, 2011). …”