Chemical ecology of a host-parasite system in Neotropical stingless bees

Abstract

The most abundant bees in the tropics are the stingless bees or Meliponini (~600 eusocial, honey-producing species). They represent ~50% of all flower-visiting bees in tropical habitats. The species richness of meliponine bees is reflected in their diverse behaviours, morphologies and ecological niches, much of which remains undescribed. One stingless bee group that has received little attention despite their potential ecological importance are parasitic robber bees of the genera Cleptotrigona in Africa and Lestrimelitta in the Americas (~24 species ranging from Mexico in the north to Argentina in the south). Unusually, robber bees do not visit flowers to collect nectar and pollen, but instead, they invade other bee nests to steal their resources, such as pollen, honey, brood food and nesting material. Chemical analyses of the cuticular hydrocarbon (CHC) profiles of two Lestrimelitta robber bee species in Mexico suggest that robber bee scouts use chemical mimicry to pass guards and spy on potential target nests before initiating a full attack. However, this "chemical mimicry hypothesis" has only been tested in Mexican robber bee species. To test whether chemical mimicry by scouts represents a more common strategy used by robber bees, we propose to analyse the cuticular hydrocarbon (CHC) profiles of the commonBrazilian robber bee Lestrimelitta limao in São Paulo state, and compare them to known victimspecies (Frieseomelitta varia, Plebeia droryana, Tetragonisca angustula, Nannotrigonatestaceicornis) as well as species that are not commonly attacked by robber bees in the studylocation (e.g. Partamona helleri, Scaptotrigona depilis, Tetragona elongata, Trigona recursa).Bee attacks appear to be non-random in both spaceand time (C. Grüter, pers. obs.). Therefore, our second aim (Aim 2) is to survey the scoutingactivity of robber bees in different locations and explore if it is linked to climatic conditions.If the "chemical mimicry hypothesis" is correct, we predict that the CHC profiles of L. limao aremore similar to victim species than to non-victim species. In addition, we predict that the scouting activity of robber bees depends on climatic conditions and is clustered in the study location. (AU)