Dominance of African racial ancestry in honey bee colonies of Mexico 30 years after the migration of hybrids from South America

The Africanized honey bee, a hybrid of Apis mellifera scutellata from Africa with European subspecies, has been considered an invasive species and a problem for beekeeping. Africanized bees arrived in Mexico in 1986, 30 years after their accidental release in Brazil. Although government programs were implemented for its eradication, Africanized populations persist in Mexico, but precise information on the patterns of genetic introgression and racial ancestry is scarce. We determined maternal and parental racial ancestry of managed and feral honey bees across the five beekeeping regions of Mexico, using mitochondrial (mtDNA, COI-COII intergenic region) and nuclear markers (94 ancestrally informative SNPs), to assess the relationship between beekeeping management, beekeeping region, altitude, and latitude with the distribution of maternal and parental racial ancestry. Results revealed a predominantly African ancestry in the Mexican honey bees, but the proportion varied according to management, beekeeping regions, and latitude. The Mexican honey bees showed 31 haplotypes of four evolutionary lineages (A, M, C, and O). Managed honey bees had mitochondrial and nuclear higher proportions of European ancestry than feral honey bees, which had a higher proportion of African ancestry. Beekeeping regions of lower latitudes had higher proportions of African nuclear ancestry. Managed and feral honey bees showed differences in the proportion of maternal and nuclear racial ancestry. Managed honey bees from the Yucatan Peninsula and feral honey bees had a higher mtDNA than nuclear proportions of African ancestry. Managed honey bees, except those on the Yucatan Peninsula, had a higher nuclear than mtDNA proportion of African ancestry. Our study demonstrates that Africanized honey bee populations are genetically diverse and well established in Mexico, which highlights the limitations of management and government programs to contain the Africanization process and demands the incorporation of this lineage in any breeding program for sustainable beekeeping.