Assessment of the genetic diversity of natural and managed populations of the native stingless bee Melipona rufiventris and of the anthropogenic movement of its colonies outside of their natural range (The Rufi Project)

Brazil has a great diversity of native stingless bees. In recent decades, numerous stingless bee species started to be breed, mainly for commercial purposes, which the activity received the name of meliponiculture. The high commercial value of their colonies and derived products has led to an intense removal of colonies from nature, which along with deforestation, forest fire and pesticide intoxication have caused a significant reduction in the wild populations and threatened with extinction the species: Melipona rufiventris, M. scutellaris and M. capixaba (Portaria MMA Number 148/2022). In addition to those threats, there are environmental risks of the colonies translocation and breeding outside of the species natural range, which have become quite common in the country. Among the stingless bee species most often traded outside of their natural ranges are the sister species: M. rufiventris, endemic of the Cerrado biome, M. flavolineata, endemic of the Caatinga biome, and M. mondury, endemic of the Atlantic Forest biome. The current federal regulations governing the use and management of stingless bees restrict breeding to the species natural geographic regions, defined by States in the National Catalog of Native Stingless Bees (Portaria ICMBio Number 665/2021), and only allow colonies exchange or swap for non-commercial purposes for breeders with up to 49 colonies within the same biome. So far, only some Brazilian States have regulations on the movement and breeding of the stingless bee colonies, and their regulations are in agreement with the federal restriction regarding introduction into non-endemic areas. The failure to comply with the governmental regulations is based on conflicts of interests, lack of information or misinformation about environmental risks, but also to the incompleteness of the regulations for breeding and commercialization. Many bee breeders (known as meliponists or meliponicultors) are unaware that the restriction on the movement and breeding of the stingless bee species outside of their areas of natural range is supported by scientific evidence, especially regarding the inter- and intraspecific introgressive hybridization. Without the reproductive isolation provided mainly by the geographic distances among the stingless bee species natural ranges, the mating between sister species is facilitated and may generate hybrids, which the repeated backcrossing with non-endemic species may lead to the complete loss of the species genetic identity by replacing their genomes by the genome of the introduced non-endemic species. A well documented example is the near extinction in Europe of the native subspecies Apis mellifera mellifera due to the intense introduction into its natural range of colonies of the non-endemic subspecies A. m. ligustica and A. m. carnica, due to the high and undiscriminated commercialization of their colonies as they are less defensive, swarm less and produce more honey. Similarly, in intraspecific introgressive hybridization, hybrid descendants can lose alleles that confer important local adaptations (allelic erosion), compromising the survival of the endemic wild populations (ecotypes). In Brazil, documented cases of interspecific hybridization are between M. scutellaris and M. capixaba, and between Tetragonisca angustula and T. fiebrigi. Therefore, the risk of the sister species M. rufiventris, M. flavolineata and M. mondury conceive interspecies hybrids is plausible. Our project (The Rufi Project) conducted an extensive genetic and taxonomic study of the natural and managed populations of the M. rufiventris, M. flavolineata and M. mondury, sampled in several regions in Brazil, to asses the genetic risks of their colonies movement and breeding outside the natural ranges, and the associated potential impact on their species conservation.