Propolis collection and colony health in the stingless bee Scaptotrigona mexicana

Stingless bees (Meliponini) have been managed by indigenous and land-based communities throughout the world for millennia. Now, the threat of stingless bee decline necessitates a careful assessment of the ways in which evolving management practices could affect stingless bee health and social immunity behaviors. In honey bees (Apis mellifera), the collection of antimicrobial resins, called propolis, contributes to social immunity. Although propolis is extremely abundant in many stingless bee nests, its impact on stingless bee health is poorly understood. We set up multiple experiments in Chiapas, Mexico to examine propolis use by the stingless bee Scaptotrigona mexicana. We monitored propolis collection by colonies housed in three different hive types over the course of one year and observed seasonal increases in propolis collection in rough box colonies, compared to colonies housed in conventional smooth wood boxes. We also manipulated propolis stores to create high-propolis and low-propolis nest environments and observed a trend toward increased colony size in high-propolis colonies. These results represent critical steps towards understanding the importance of propolis to stingless bee social immunity, and could help inform management practices that support the natural defenses stingless bees use to bolster colony health.