The mite Varroa destructor is one of the most dangerous parasites of the Western honeybee (Apis mellifera) causing enormous colony losses worldwide. Various chemical treatments for the control of the Varroa mite are currently in use, which, however, lead to residues in bee products and often to resistance in mites. This facilitated the exploration of alternative treatment methods and breeding for mite resistant honeybees has been in focus for breeders in many parts of the world with variable results.

Sex determination is one of the major developmental events in higher metazoans, where complex molecular mechanisms define two physiologically and behaviorally distinct organisms still genetically compatible. In honey bees, the sex determination cascade is initiated by the allelic composition of complementary sex determiner (csd ) gene: males develop from hemi or homozygous embryos, whereas females develop from heterozygous embryos. In females, different alleles of csd lead to the formation of female-specific variants of feminizer (fem ) and doublesex (dsx ). In males, male-specific variants of fem and dsx are formed by default. In this paper, we investigated the genes of sex determination in the stingless bees Melipona quadrifasciata , Scaptotrigona postica , and Frieseomelitta varia . Our results revealed that the architecture of fem and dsx transcripts is highly conserved among the three stingless bee species, and also with honey bees. stingless bees / sex determination / Melipona quadrifasciata / Scaptotrigona postica / Frieseomelitta varia