Differences in the resource intake of two sympatric Australian stingless bee species

Tetragonula carbonaria and Austroplebeia australis are two species of eusocial stingless bees with phylogeographically different origins that can occur sympatrically on the Australian east coast. We studied their foraging activity and resource intake and found pronounced differences between species. Tetragonula carbonaria showed consistently higher flight activity (resulting in a higher sugar intake per minute) and thus likely collected more resin and more pollen from a broader plant spectrum than A. australis. In contrast, the smaller A. australis colonies tended to collect a narrower resource spectrum and focused on high-quality resources (i.e., nectar of significantly higher sugar concentrations). Tetragonula carbonaria colonies also gained more weight over the study period than A. australis colonies, but colony growth may nevertheless be similar between the two species, albeit resulting from differences in resource allocation and exploitation as well as worker lifespan. Given their overlapping geographic ranges, T. carbonaria and A. australis may have evolved different patterns with regard to the use of resources to avoid exploitative competition between species or due to constraints imposed by their different phylogeographic origins.