Genetic structure of the commercial stingless bee Heterotrigona itama (Apidae: Meliponini) in Thailand.

Stingless beekeeping, also known as meliponiculture, has gained increasing popularity in many tropical and subtropical countries for its use in commercial pollination and high-value honey and propolis production. However, this rising interest in stingless beekeeping has led to significant geographical displacements of bee colonies by beekeepers, occasionally surpassing their native ranges. Consequently, this affects local bee populations by disrupting gene flow across unnaturally large geographic scales. For Heterotrigona itama, one of the most common stingless bee species in Southeast Asian countries, including Thailand, there is concern that large-scale artificial propagation by beekeepers utilizing a limited number of bee colonies will lead to inbreeding. This practice leads to increased inbreeding within managed populations and introgression into wild populations. These concerns highlight the need for careful management practices in stingless beekeeping to mitigate potential adverse effects. To assess the genetic structure of H. itama in Thailand, 70 colonies were sampled, and partially sequenced cytochrome c oxidase subunit 1 (COI) gene, large ribosomal subunit rRNA gene (16S rRNA), and 28S large ribosomal subunit rDNA gene (28S rRNA) were analyzed. Our results showed slightly lower nuclear genetic variability, but higher mitochondrial genetic variability, which can be attributed to gene flow, colony transport, and nest division. We suggest that increasing the number of colonies maintained through nest division does not negatively affect genetic variability, as it is maintained by small-scale male dispersal and human-mediated nest transport. However, caution should be exercised when transporting nests from distant localities, considering the high genetic differentiation observed between samples from Narathiwat and those from Krabi and Nakhon Si Thammarat provinces, which might indicate local adaptation.