UC San Diego

Genomic admixture, the mixture of two or more distinct gene pools, is a common and widespread biological phenomenon of significant evolutionary importance. The African-hybrid honey bee (AHB) represents one of the most impressive and ecologically successful cases of admixture in a social insect. While honey bees are now a common feature of the American landscape and an indispensable part of commercial agriculture, their origins are rooted in importations from Eurasia and Africa that began in the 1500s. The African-hybrid honey bee (AHB) is a New World amalgamation of several subspecies of the western honey bee (Apis mellifera). Apis mellifera is a taxonomically diverse species, comprised of more than 30 subspecies historically grouped into four major biogeographic lineages: African (A), Western European (M), Eastern European (C), and Eastern Mediterranean (O). In 1956, honey bee biologists in Brazil imported honey bee queens of the African subspecies Apis mellifera scutellata for experimental breeding with pre-existing European stock. Researchers hoped to forge a honey bee that combined the tropical hardiness of A. m. scutellata with the honey production capabilities and gentleness of the popular European subspecies currently in use. In a now infamous incident, these experimental “Africanized” hybrids were accidently released from their research apiaries, initiating a spectacular hybrid species expansion that now extends from northern Argentina to northern California (U.S.A.). The heightened degree of territorial nest defense characteristic of African-hybrid honey bees spurred a large degree of public concern over the expansion and success of this invasive insect—gaining it substantial attention from popular press who dubbed it the “killer bee”. To this end, this dissertation seeks to characterize genomic admixture dynamics and nest defense behavior in the African-hybrid honey bee. I hope my work serves to inform adaptive honey bee breeding practices that will aid in the preservation of a robust population of honey bees for commercial pollination and help combat world-wide honey bee declines.