Does resin represent a neglected component of bee ecology? A comparison between Old and New World bees

Background/Question/Methods

Worldwide, populations of managed Apis bees face declines, with the underlying reasons still remaining largely unknown. Honeybees have been bred for centuries to increase their economic value as pollinators and honey producers, with a preference for bees that focus on honey and pollen instead of resin collection. The highly social stingless bees (Apidae: Meliponini) are closely related to Apishoneybees. But in contrast to honeybees, they also collect large amounts of plant resins which they use for nest construction, defense and to transfer resin-derived compounds to their body surfaces, thereby increasing the diversity and complexity of their chemical profiles.

Results/Conclusions

We collected stingless bees from three different continents (Asia, Australia and America) and compared their chemical profiles. We found resin-derived compounds to be a predominant characteristic of paleotropical stingless bees, where 73 % of the species had significant amounts of these compounds in their chemical profiles. By contrast, only 56 % of the neotropical species studied enriched their profiles with resinous compounds.

To better understand the role of resin for stingless bees, we compared resin foraging, the prevalence of resin-derived compounds in nest material, and defensive properties of resin and resin-derived compounds on the bees’ body surfaces for two Australian stingless bee species. Australia is unique in comprising stingless bees of two genera with likely different geographic origins: Tetragonula from Southeast Asia and Austroplebeia from Africa/America. Whereas Tetragonula bees have a high proportion of resin-derived compounds in their chemical profiles, Austroplebeia bees are lacking such compounds. We found that species of the two genera strongly differed in their collection behavior and usage of resin, with Austroplebeia bees being more vulnerable to predatory attacks than Tetragonula bees. These results suggest that resin represents a highly important and largely neglected component in the ecology of bees.