Removal of clay by stingless bees: load size and moisture selection

Abstract

Some organisms disperse energy, associated with the transportation of resource, which is not necessarily food. Stingless bees of Central Amazonia (Melipona flavolineata and M. lateralis) collect clay in banks along streams for nest building. The moisture of the clay varies along the bank, and bees collect clay from specific location, indicating that there is some sort of preference regarding their selection. This study aims at identifying: if larger bees carry more clay; if there is a preference for moisture of substrates; and if bees are less efficient accumulating and transporting clay when it is wet. In order to do so, I measured the size of the bees and of the pellets of clay found in the corbicula. I set up a field experiment to test substrate preferences. The amount of clay transported, increased exponentially in accordance to the size of the bee, and the preferred substrate was the driest clay. The amount and the efficiency of removal of clay were not affected by the moisture of the substrate. Despite the wet clay being denser, it does not reduce the efficiency of exploitation of the resource, but suggests that bees spend more energy to carry the same quantity of wet clay, which may be the underlying mechanism explaining their preference for removing drier clay.

Foraging pattern and harvesting of resources of subterranean stingless bee Geotrigona subterranea (Friese, 1901) (Hymenoptera: Apidae: Meliponini)

“…The occurrence of this activity only during the afternoon can be explained by the low moisture of the material in the hottest time, allowing that detritus to be more easily transported. Costa-Pereira (2014) found that two species of Melipona collect clay with less moisture to reduce the energy cost during transport.…”