Original article Sounds in Melipona costaricensis (Apidae: Meliponini): effect of sugar concentration and nectar source distance Ingrid AGUILAR a *, Daniel BRICEÑO b a Centro de Investigaciones Apícolas Tropicales, Universidad Nacional, PO Box, 475-3000 Heredia, Costa Rica b Escuela de Biología, Universidad de Costa Rica, San José, Costa Rica (Received 7 July 2001; revised 2 January 2002; accepted 13 February 2002) Abstract – The principal finding presented here is that Melipona costaricensis produces sounds that vary sig- nificantly in relation to varying sugar concentrations. Several components of the sounds produced, during the bees’stay inside of the hive, were positively correlated with sugar concentration: song duration, probability of sound production, duration of the long pulses and the relationship between short / long pulsed sound. Number of pulses per song was negatively correlated with sugar concentrations. The duration of all sound pulses was significantly correlated with the distance of the food source. Duration of the short pulses and interpulses were significantly affected by the distance of the food source. Sounds may contribute to the recruitment of nestmates to increasingly rich food supplies during the day. It is clear that aspects of the sound signals are cor- related with profitability of food sources. sound production / sugar concentration / distance / food source /stingless bees 1. INTRODUCTION When a foraging social bee (Apidae: Meliponini) finds food, it returns to the hive and may recruit nestmates to that source. Through recruitment, which implies some mechanism of communication, newly avail- able food sources can be exploited more effi- ciently (von Frisch, 1967). The known mechanisms for recruitment vary considerably between species of Apidae. They include olfac- tory, taste and acoustic cues (Lindauer and Kerr, 1958; Esch et al., 1965). It has been found that honey bees give information about direc- tion and distance of food sources by perform- ing dances on the vertical combs in the hive (von Frisch, 1967). Esch (1964) and Esch et al. (1965) demonstrated that sound signals are also an important element of honey bee dances and apparently they are an adaptation to danc- ing at low light intensities inside the nest (Kirchner et al., 1996). These signals are air- borne sounds of high intensity produced by dorsoventral vibrations of the wings (Michelsen et al., 1987; Kirchner et al., 1988). Their sounds consist of short pulses at a repeti- tion rate of 15 Hz (Kirchner, 1993), they do not have a long continuous pulse sound. The duration of sound pulses during each performance of both the round dance and the waggle dance increases with distance between the hive and the feeder (Esch et al., 1965; Waddington and Kirchner, 1992; Kirchner and Dreller, 1993). Sounds produced during round and waggle dances are necessary for successful communication (Michelsen et al., 1989; 375 * Correspondence and reprints E-mail: iaguilar@una.ac.cr Apidologie 33 (2002) 375–388 © INRA/DIB-AGIB/EDP Sciences, 2002 DOI: 10.1051/apido:2002023