Apis mellifera scutellata (Lepeletier)

Africanized honeybees (AHB), Apis mellifera scutellata, are the hybrid offspring resulting from the crossing of domestic or naturalized honeybees (Apis mellifera) of European descent and descendants of the more aggressive African honeybee strain, A. m. scutellata, that was intentionally brought to the New world for cultivation and later accidentally released to the environment. They are sometimes dramatically referred to as "killer bees."African honeybees have bodies that are covered in fuzz with an abdomen that is ringed with black stripes. They are very similar in appearance to European honeybees, although they are slightly smaller (Kaplan 2004, ISSG 2005).

The native range of Apis mellifera scutellata is the eastern and southern portions of Africa. Introduction to the New World began with the intentional importation and subsequent accidental release in Brazil followed, in turn, by spread of the strain through Central- and South America and into the southern U.S. (Sanford and Hall 2005).The known introduced U.S. range now includes portions of California, Nevada, Arizon, New Mexico, Texas, Oklahoma, Arkansas, Louisiana, and Florida. The strain is considered to be officially established in Florida. As of March 2006, Africanizede honeybees had been reported from 14 Florida counties, including the southern three counties (St. Lucie, Martin, Palm Beach) of the India River Lagoon watershed.

It is exceedingly difficult for a non-entomologist to positively distinguish Africanized honeybees from common European honeybees. Aside from genetic analysis, comparison of as many as twenty different body measurements remains the only way to distinguish the strains with certainty (Kaplan 2004).Apis mellifera scutellata are most easily recognized for their behavioral dissimilarities to European honeybees. They respond quickly and aggressively to disturbance, defend hives more intensely than European honeybees and will chase the source of the disturbance for a mile or more (Sanford and Hall 2005).

Apis mellifera scutellata co-occurs with and typically hybridizes or outcompetes the European honeybee strain in Florida.Invasion History: The history of the introduction of Apis mellifera scutellata to the Americas is well-documented. The strain was first domesticated in the scrub desert environment of central South Africa and became known as an aggressive but productive, disease-resistant strain that produced quality honey.Growth of the honey industry in Brazil In the 1950s was tempered by relatively poor performance of imported European honeybees. In 1956 the Brazilian government sent a geneticist named Warwick Kerr to collect African honeybee queens to bring back for experimental breeding. Interbreeding African queens and European drones (via artificial insemination) produced the hybrid strain that came to be known as Africanized honeybees (Kerr 1967, Winston 1992).The accidental release by a Brazilian beekeeper of more than two-dozen AHB queens in 1957 led to widespread hybridization with naturalized European honeybee populations. The reasonable assumption that outcrossing would quickly dilute the aggressive tendencies of the Africanized strain proved to be incorrect as reports of feral bee swarms attacking livestock began to multiply.Africanized honeybees spread rapidly through continued outcrossing with naturalized honeybee populations, from Brazil up though South America and into Central America and Mexico. The strain first arrived in the United States in 1990, when they were identified near Hidalgo, TX (Kaplan 2004).From 1995-2005, A. m. scutellata were captured in bait hives maintained by Florida Department of Agriculture and Consumer Services staff at shipping ports such as Jacksonville, Miami and Tampa. Throughout this period, Africanized bees appeared unable to gain a foothold in the state (Woods 2005).As of 2005, however, established A. m. scutellata populations have been documented in more than a dozen counties in peninsular Florida. The arrival in Florida appears to be disjunct to the spread of A. m. scutellata from Texas. More likely, Florida introductions were human-facilitated as shipping, trucking, and/or rail transport may have accidentally carried undetected Africanized bees into the state. Potential to Compete With Natives: The rapid spread of Apis mellifera scutellata into new areas is largely accomplished through hybridization with naturalized European honeybees. The reproductive advantages enjoyed by A. m. scutellata (see above) typically allow it to eventually dominate areas formerly occupied by naturalized European strain colonies (Kaplan 2004).European honeybee colonies can also be directly taken over by Africanized bees. Takeovers are perpetrated by swarming or absconding queens and a contingent of workers and appear to primarily be a means to gain access to favorable nest sites, food resources, and/or large worker populations (Vergara et al. 1993). Queenless colonies and small or failing colonies are most likely to be taken over but large, strong colonies can be infiltrated as well (Rinderer and Helmich 1991) The actual process of colony takeover is complex and not entirely understood, but it involves the initial acquisition of the resident colony odor by invading Africanized bees prior to hive invasion and killing of resident queens if present (Vergara et al. 1993). Possible Economic Consequences of Invasion: Honeybees may be the most economically important insects in the world. The first European honeybees were brought to the New World perhaps three centuries ago, and the economic benefit of this historic introduction here and elsewhere throughout the world is incalculable. In addition to producing honey and beeswax, honeybees also pollinate a great many agricultural crops. A 2007 New York Times article cited a Cornell University study estimating the annual value of honeybee crop pollination in the U.S. at more than $14 billion.The notion that African honeybees are "killer bees" is largely hyperbole, although a handful of U.S. fatalities (and at least 175 from Mexico since 1985) indicate that Africanize hives should be treated with caution. Although the sting of a single Africanized bee is no worse than that of a single European bee, Africanized bees do swarm more readily and defend the hive more aggressively than European varieties.If the number of Africanized bee colonies continues to expand, takeovers of cultivated European hives by Africanized queens during periods of high swarming could cause considerable problems for Florida beekeepers. Potential economic problems for Florida beekeepers if their stocks became Africanized are probably those relating to the tendencies of A. m. scutellata for producing less stored honey and for excessive swarming and nest abandonment (absconding). None of those attributes are desirable in cultivated honeybee hives.