The Africanized Honey Bee (AHB), frequently sensationalized as the “killer bee,” is a hybrid insect whose presence in the Americas is not a result of natural migration but a direct consequence of a specific scientific event. This bee subspecies has become an established part of the ecosystem across much of the Western Hemisphere, rooted in an attempt to improve beekeeping. This article details the intentional importation, the accidental release, and the resulting biological spread of the Africanized Honey Bee.
The Brazilian Experiment
The intentional introduction of African bees to the New World was driven by the poor performance of European honey bees (EHB) in South America’s tropical climate. European subspecies, adapted to temperate zones, struggled to thrive and produce sufficient honey in Brazil’s consistently warm conditions. Their tendency to store large amounts of honey for long winters was a disadvantage where nectar flow was continuous year-round. In 1956, Brazilian geneticist Dr. Warwick Kerr imported African honey bee queens to an agricultural research station near Rio Claro, São Paulo. The goal was to crossbreed the hardy African stock with the more docile European bees already present. The hope was to create a hybrid strain that retained the African bee’s superior foraging traits and resistance to tropical conditions while adopting the European bee’s milder temperament.
The 1957 Escape
The creation of the Africanized Honey Bee began with an unforeseen accident at the experimental apiary in 1957. African queens and their colonies were initially kept in quarantine hives fitted with specialized screens called queen excluders. These excluders were intended to prevent queens and drones from leaving the hive to mate with local European populations, thereby maintaining genetic control over the breeding program. In October 1957, a visiting beekeeper reportedly removed the excluders from the hive entrances, believing they were hindering the worker bees’ movement. This resulted in the accidental release of 26 African swarms into the nearby environment. These escaped bees quickly began to hybridize with the feral European honey bee colonies. The resulting hybrid offspring inherited the highly defensive nature of the African bee, exhibiting a rapid and intense response to disturbances. The aggressive African genetics proved dominant in the wild, establishing a new, rapidly reproducing population. This accidental release in Brazil became the single source population for nearly all Africanized Honey Bees that would eventually colonize the Americas.
Mapping the Spread
Following the 1957 escape, the Africanized population began a relentless northward expansion, successfully colonizing vast areas due to their superior tropical adaptation. They spread at an average rate of 200 to 300 miles per year, facilitated by their tendency to swarm frequently and establish new, smaller colonies. Their ability to out-compete and genetically overwhelm European colonies allowed them to dominate the feral bee population across South America. The bees crossed into Central America by 1982 and reached Mexico by 1985. The first natural colony was officially confirmed in the United States near Hidalgo, Texas, in October 1990. By 1993 and 1994, they had established populations in Arizona and California, respectively, and have since spread across several southern and southwestern states.
Distinguishing Africanized Bees
Visually, Africanized Honey Bees are virtually indistinguishable from European Honey Bees, sharing the same species designation and being only slightly smaller. Reliable differentiation requires laboratory analysis, primarily using morphometrics and DNA testing. Morphometrics involves the precise measurement of various body parts, such as wing length and leg segments, using standardized protocols like the Fast Africanized Bee Identification System (FABIS). This technique calculates the probability of a bee being Africanized based on these measurements. DNA analysis, specifically mitochondrial DNA testing, is used to determine the bee’s maternal lineage, confirming descent from the African subspecies Apis mellifera scutellata. In the field, the most immediate sign of Africanization is behavioral: Africanized bees respond to disturbance with extreme hyper-defensiveness, sending out hundreds of defenders and pursuing a threat over greater distances than their European counterparts.