UC San Diego

Social bees can deposit specialized glandular secretions, or signals, that allow foragers to revisit rewarding and to avoid unrewarding food sources. However, it is not known if bees can orient towards olfactory cues such as excreta deposited near food sources. We report that Melipona mandacaia foragers (stingless bees) deposit an odor cue, anal droplets, and a previously undescribed ventro-abdominal odor on food sources. Surprisingly, foragers deposited attractive odor marks on good food sources to which they recruited and on poor food sources to which they did not recruit. Foragers left the most anal droplets on dilute food sources to which they did not recruit (1.25-M sucrose solution), yet returning foragers were attracted to anal droplets obtained on poor food sources and presented in bioassays. Foragers were attracted to ventro-abdominal odors obtained on good food sources (2.5-M sucrose solution). Chemical extractions suggest that odor marks contain attractive polar compounds. We also provide the first detailed description of forager waggling and spinning behavior on poor and good food sources. Waggling may be a method of dispersing anal droplets and spinning may help foragers learn local landmarks.