"The Africanized Honey Bee in the Americas:  A Biological Revolution with Human Cultural Implications"

American Bee Journal (2006), Five Parts, March thru July.

 

This document is an expanded version of  what was  published in the American Bee Journal

 

By

 

Dr. Malcolm T. Sanford

http://apis.shorturl.com

 

 

Introduction: 

 

Too much it seems cannot be said about the Africanized honey bee in the Americas, especially when it is referred to by its more sensationalized names, “abeja asesina” in Spanish or “killer bee” in English.  Unfortunately, these names conjure up an insect that exists on planet earth for one purpose, to kill.  And not only can it kill but in a most horrible and gruesome way via a barbed sting filled with life-destroying venom.  This killer bee image, like that of sharks, tigers and other species known to harm humans, continues to be perpetuated in the mind of the average citizen, who knows little about insects in general and honey bees in particular.  Perhaps the most concrete example of this is the large fiber glass and steel statue of the bee constructed by the citizens of the City of Hidalgo, Texas, where the Africanized bee was first observed to have crossed the border into the United States of America.  This statue was originally mounted on a cart and continues to be trotted out during festivals and other occasions as a way to provide publicity for the town of Hidalgo but, in a real way, continues the myth that somehow the Africanized honey bee is larger than life.¹

 

It’s time to get over this sensationalized image and put a realistic perspective on the Africanized honey bee.  This social insect is nothing more than a honey bee with the same scientific name of all its cousins worldwide, Apis mellifera.  It is virtually indistinguishable at a glance from the other honey bees found in, but not native to, the Americas.  It is the result of only one of literally hundreds of honey bee introductions that have occurred over the last 300 years into the New World. 

 

Although referred to as a particular insect, it may be more relevant to view the Africanized honey bee as an evolutionary “work in progress,” rather than a finished product.  It is the result of a revolution that can occur when any living entity is introduced into a biological system.  The list of such species across the world is very long and each has its own story.  How systems react to these introductions has been dubbed the “Nemesis effect” by Chris Bright in World Watch Magazine, ² who describes the results of this phenomenon as unforseen and destructive.  The Africanized honey bee’s introduction certainly contains many of the characteristics described as part of the “Nemesis effect.”

 

What makes the Africanized honey bee revolution unique is its direct human cultural implications.  For not only is the honey bee of significance to the average citizen because of its biological activity and defensive behavior, it is also the basis for an agricultural industry consisting of products and services this insect provides to humanity.  The purpose of this publication is to describe the history of the Africanized honey bee in the Americas and provide some perspective regarding its present and potential impact on human culture and activity in that part of the globe.

 

History of the Biological Revolution:  Origin of Honey Bees

 

Honey bees are an Old-World species, thought to have originated in Asia.  They are in the genus Apis, which is thought to be based on the Egyptian word for “sacred bull.”  There are seven or so species of Apis bees identified world wide, and, with new taxonomic tools (DNA analysis) available today, more species no doubt can be expected in the future.  A comparison of species coloration is found at Dr. J. Woyke’s World Wide Web page.³  It is thought that bees in Asia such as Apis dorsata, A. florea and others gave rise to both the Eastern honey bee (Apis cerana) and the only species that now has worldwide distribution, Apis mellifera.  This is the western honey bee, sometimes referred to as Apis mellifica in European scientific literature.  The western honey bee is a social insect that lives in relatively large colonies consisting of three morphologically distinct individuals (queen, drone, worker) and has a complex division of labor.  This insect is most known for its production of honey, a sweet that humans have craved over centuries and, thus, when Homo sapiens migrated from the Old to the New World, the honey bee was taken along.  The aborigines in North America called the honey bee “the white man’s fly,” appropriately giving it a deserved human association, although it is not a fly in the insect order Diptera, but in the order Hymenoptera.

 

From now on in this publication, the term honey bee will refer specifically to the Western honey bee (Apis mellifera).  A special quality of the honey bee is that, unlike most solitary or primitively-social insects, it develops a perennial nest that continues year after year.  In addition, the insect has the ability to regulate its colony temperature and, thus, can persist in extremely hot and/or cold environments.  This is the reason that the honey bee can be found almost anywhere on the globe from the tropics to the polar circles.

 

Apis mellifera in the Americas:  The European Honey Bee

 

Many subspecies, often called “races,” of Apis mellifera exist.  In northern Europe, the prevailing subspecies are Apis mellifera mellifera (German or dark bee), Apis mellifera ligustica (Italian bee), Apis mellifera caucasica (Caucasian bee) and Apis mellifera carnica (Carniolan bee).  In Spain is found Apis mellifera iberica (named for the Iberian peninsula).

 

It is important to understand that all subspecies of Apis mellifera readily interbreed, effectively exchanging genetic material.  Thus, the existence of any kind of genetically pure honey bee subspecies is extremely rare.  However, over the centuries certain populations of honey bees with specific adaptations, somewhat isolated from each other over time, called “ecotypes,” have flourished in specialized environments.  Ecotypes have certain behaviors that allow them to persist in specific climatological conditions in conjunction with prevailing plants (flora) of an area.  Two large regions of the earth that have a number of indigenous honey bee races or ecotypes are Europe and Africa.

 

The earliest European honey bee ecotypes brought over by the Spanish and English were probably predominantly Apis mellifera iberica (Iberian peninsula) and Apis mellifera mellifera (north west Europe), respectively, but this is not known for sure.  Others were introduced later, including species from the middle east (Apis mellifera syriaca) and North Africa (Apis mellifera lamarckii).  Perhaps the most common type in North America is the Italian ecotype Apis mellifera ligustica, and is the one predominantly in use by beekeepers.  Like most European honey bees, this race survives in temperate conditions characterized by more or less defined seasons.  It is also adapted to temperate plants that flower based on photoperiod (day length).  Most importantly, it is suited to surviving cold, generally continental climatic conditions.  This means it lays in a large store of surplus honey (usually more than the colony needs).  It is this surplus that the beekeeper harvests, which can be removed without risking the death of a colony due to lack of food (starvation).  The ability to judge how much honey to take while still leaving the colony enough to survive a cold temperate winter is one of the traits of a master beekeeper. 

 

European honey bee ecotypes reproduce by swarming, where replacement queens are reared and a colony splits in half with a new queen heading up the parent colony and the original queen flying off with a complement of bees (swarm) to find another home.  This is similar to vegetative reproduction in plants.  Usually there is a defined swarming season in temperate climates, and colonies usually swarm once or sometimes twice during that time.  European honey bee ecotypes have relatively few enemies and are usually not characterized as “defensive.”  The “gentleness” of managed European honey bees is considered to be the result of many years of selection by human beekeepers.  This does not mean that all European honey bees are gentle.  Certain colonies may even be selected for fierceness to avoid them being vandalized.  Colonies found in the wild may also be more defensive, though not necessarily so.

 

Apis mellifera in the tropics: The African Honey Bee

 

It is thought that over millennia the African and European races of Apis mellifera are the result of groups of honey bees that migrated out of Asia where more primitive races are still found.  Although only a handful are found in Europe, over thirty-five races have been described in Africa; many having developed into ecotypes that survive well in tropical rather than temperate conditions.  In the tropics, rainfall rather than temperature determines the yearly season, and plants depend more on precipitation than photoperiod.  Honey bee reproduction is more important in the tropics than in temperate areas, and so is migration.  Both are accomplished by swarming.  Thus, tropical honey bees swarm more than European honey bees on the average.  There is a relatively greater number of enemies (parasites and predators, including humans) in the tropics, known for its biological diversity, which often produces highly defensive reactions in honey bees.  Ecotypes in the tropics more easily abandon their nest (abscond) when challenged by disease, predation or lack of resources.  Ecotypes in the temperate zone do not abscond as readily.

 

Many of the tropical honey bees of Africa have a relatively larger defensiveness and swarming quotient than their European cousins, along with a greater propensity to abandon the nest (abscond) should resources run low or the nest be overrun by diseases or pests.  And it is behavior, not structure (morphology), that is the greatest difference between the honey bees of the tropics and those inhabiting the temperate zones.

 

Tropical versus Temperate Honey Bees:  The Basis for Africanization in the Americas

 

The story of the Africanized honey bee, therefore, is firmly rooted in behavioral differences between tropical and temperate honey bees.  The first bees brought to the Americas were European honey bee ecotypes, adapted to the harsh winters and predictable plant phenologies of the temperate zones.  They also reproduced based on fairly predictable climatic cues of predominantly climax vegetation and regular photoperiods.  They were “stay-at-home insects,” swarming infrequently and seldom abandoning their nests in times of stress.  In temperate North America, European honey bees flourished like many introduced species that quickly occupy a new niche or ecological vacuum, and in a way paralleled the westward expansion of their human, European counterparts as they too settled the rich North American continent.  Centuries of human selection also produced gentle (not defensive) European honey bees, such that they might be considered by some as very close to domestic animals.⁴

 

Over time, it became apparent that European honey bees, adapted to temperate zones did not flourish as well in the American tropics.  They were simply not in tune with the environment. A list of the differences between tropical and temperate honey bees is detailed by Dr. Mark Winston.⁵  These include nest characteristics (volume and cell size), individual life span (shorter for Africanized bees), age-based worker behavior, colony growth and reproduction, drone rearing, and seasonal patterns of swarming and absconding.  The latter two qualities (swarming and absconding) are perhaps the most dramatic differences seen between these two kinds of honey bees and have led to the phenomenal migration success of the Africanized honey bee.  Although generally this is the case, it should be stressed that it does not hold across the full extent of the environments in question.  For example, although a large beekeeping industry based on European honey bees never flourished in sub tropical Brazil, it did in the Yucatan of Mexico, which in the 1940s and 50s was the world’s largest honey exporting region.

 

It was in Brazil that one of the seemingly universal behaviors of human behavior occurred setting the stage for the Africanized honey bee story; introduction of genetic material to improve local stock.  Dr. Warwick Estevam Kerr, an eminent Brazilian geneticist, who was travelling to Africa to study native “stingless” bees (not honey bees), was prevailed upon to search out productive tropical honey bees in Africa and bring them back to his country

 

Dr. Kerr’s story is a fascinating one of science mixed with politics.  Perhaps the best treatment is that by Wallace White.⁶  According to Mr. White, Dr. Kerr was originally asked to import queens from Angola, South Africa and Tanzania.  All those from Angola died, but Dr. Kerr arrived in Rio de Janeiro with seventy-five from South Africa.  Dr. Kerr was aware that African honey bees, although productive, were also likely to be fiercely defensive, far more so than the gentle European (Italian) bees then employed in Brazilian apiculture.  Thus, he used precautions by introducing the queens into nuclei (small colonies) of European bees and quarantining the colonies in the Rio Claro area.  The idea was to control the genetics through instrumental insemination or II. 

 

Mr. White reported that after some selection and natural mortality, 28 or 29 nuclei became the basis for the breeding effort by Dr. Kerr.  From these colonies a group of queens were reared and inseminated from sperm of European (Apis mellifera ligustica) drones.  Selection from the first cross, or F1 hybrid, produced daughter queens for subsequent generations.  One queen in particular from Tanzania produced colonies that appeared more productive but, unfortunately,  were extremely defensive as well.  All was progressing well until one day in the fall of 1957 when a visiting beekeeper removed the barriers (queen excluders) keeping the queens from escaping.  Twenty-six of the queens accompanied by swarms of workers left these hives and are considered the origin of the so-called Africanized honey bee.

 

Although there has been much emphasis on the queens’ role in the process, Mr. White reported that Dr. Kerr believed the importance of drones should not be underestimated.  Thus, if each of the daughter queens of the twenty-six swarms (queens) was mated by as many as seventeen drones, this would have fantastically increased the plasticity and viability of the population.  In any case, the hybrids that resulted from these matings began spreading rapidly. 

 

Again, the changes observed in Brazil were due to the shift from European temperate honey bee behavior to that of the African tropical honey bee, as described elsewhere in this publication.  The one that has received the vast majority of the attention, however, and continues to do so today is defensive behavior.  Many wild colonies and, more significantly, managed colonies by beekeepers in Brazil and elsewhere in the American tropics have become much more defensive in the wave of the continent’s shift to Africanized honey bees.  This has led to stinging incidents that have generally been over sensationalized by media outlets.

 

Defensive versus Aggressive Behavior in Honey Bees

 

Stinging behavior by honey bees has evolved as a strictly defensive measure and is usually confined to protecting the nest or colony.  Honey bees in the field seldom sting and are never “aggressive,” that is, seek out hosts to sting.  However, most writings in the lay press and reports on television about honey bees emphasize the latter term, not the former.  This habit unfortunately has also crept into the scientific and even beekeeping communities.  Thus, honey bees often appear to the sensitized general public as simply “aggressive.”  And because people and animals have been killed by these insects, it probably is inevitable that the term “killer bee” would be coined and continues to be used with reference to honey bees, particularly those found in the tropics usually referred to as “Africanized.”

 

It is emphasized that defensive behavior is a relative term.  Perhaps the most gentle bees this author has observed are those of the Ile d’Yeu off the Northwest Coast of France.⁷  These are considered pure caucasian honey bees (Apis mellifera caucasica).  In comparison, almost all other honey bees might be classified as “over-defensive.”  On the other side of the spectrum, this author has observed honey bees in Costa Rica, Honduras, and Mexico that can only be described as very fierce.  Between the extremely fierce and placidly gentle, however, exist the vast majority of honey bees that are "somewhat" defensive.  These differences can really only be measured on a probabilistic scale.  It is important to realize that the whole range of defensive behavior can also be seen in colonies even within the same bee yard at times.  It is a well-known beekeeping practice, for example, for very defensive colonies to be located in the periphery of a bee yard to deter vandalism or theft.

 

Studies in Africanized honey bee areas indicate that not all colonies of bees become over-defensive, but even a minority of such colonies within an apiary or operation may cause abandonment of apiaries by beekeepers.⁸  Since defensive behavior is really what beekeepers and the general public are concerned about with reference to Africanized bees, one of the more reasonable, but not scientifically acceptable, ways to identify these bees is to provoke an attack (i.e. kick a hive) to see the kind of defensive behavior elicited.  A beekeeper with experience working colonies very quickly can judge a range of defensiveness shown in a colony or apiary and can take appropriate measures from applying more smoke to exiting the apiary to requeening colonies considered over defensive.  Many beekeepers believe that the most defensive colonies are the better honey producers.

 

New research techniques may provide some innovative ways to manage stinging behavior:  Drs. E. Guzman-Novoa and G. Hunt, for example, have developed specific gene markers that are associated with the probability of queen bees having the African version of stinging genes so it will be easier for breeders to avoid using them.  They conclude: "Now that we have the markers we can selectively breed for gentle bees."⁹  The DNA markers are available to other scientists to determine if honey bee populations in their regions have genes for aggressive behavior. This research also could lead to the isolation of genes that influence bee behavior and suggest ways to decrease stinging incidents.

 

Spread of the Africanized Honey Bee in the Americas

 

The Africanized honey bee has truly taken the Americas by storm.  It marched out of Brazil in the late fifties and entered the United States in 1990, taking only a little more than 40 years to make the journey.  This was natural movement; not exacerbated by human introductions of populations, showing that the Africanized honey bee is a migratory insect par excelance.

 

Countries first receiving migrations of Africanized honey bees were Brazil’s neighbors, the Guianas and Venezuela to the north and Paraguay, Uruguay, and Bolivia to the south and west during the 1970s.  Later, the bee arrived in the west-coast countries of Colombia, Ecuador and Peru.  Argentina and Chile were also affected and are special cases, given their temperate climates.  The invasion navigated the Darien peninsula and moved quickly through Central America and Mexico in the 1980s. 

 

There are studies of the Africanization process in several of these countries.  Perhaps it is best documented in French Guiana, Venezuela and Peru in the 1970s and Costa Rica in the 1980s.  The Venezuelan experience was seminal in that it was studied intensively by several research groups and produced many students who are today actively involved in honey bee research and educational activities.  Of special significance were those mentored by Dr. Orley (Chip) Taylor¹⁰ University of Kansas and Dr. Thomas Rinderer of the USDA’s Baton Rouge Lab (Honey Bee Breeding, Genetics and Physiology Research Laboratory.¹¹ 

 

Venezuela was colonized in the mid 1970s by Africanized honey bees migrating from the Guianas and Brazil.  Mirroring their migration in most other areas of the tropics, they moved 300-400 kilometers a year and finally entered Colombia in 1981.  Reports of the bee’s impact on beekeeping in the country became the reference point for much of the subsequent sensationalized press coverage in both beekeeping and lay publications.  This included a drastic decline in honey production, average colony yields dropping from 75 to 125 kg/year to as low as 25 or less.  The total crop also reflected these numbers; Venezuela produced only 78 metric tons of honey in 1981 and no longer had any surplus for export¹².  Venezuela suffered more than other countries subsequently invaded by the bee due to lack of information about how to manage the insect in either an apicultural or public health context at the time.

 

The Costa Rican experience was studied extensively by Dr. Marla Spivak.¹³  She looked at different aspects of the migration based on elevation and found what was later to be recognized in many zones of active Africanization, that altitude made a difference in the process.  Thus, in the hot, tropical lowlands there was rapid establishment of migratory swarms and abrupt changes in local bee populations.  At higher elevations, the Africanization process did not occur so quickly.  The final distribution of Africanized traits also appears to mirror this, as anecdotal evidence, from Peru to Mexico.  There is some controversy about the altitude at which tropically adapted Africanized bees can be found.  Research on certain colonies shows that they can persist at fairly cold temperatures.¹⁴

 

The question is not whether Africanized honey bee colonies survive, however, but if a viable population with strongly Africanized characteristics can establish itself at high altitudes.  Peru, for example, has areas where the Africanized bee has not persisted.  As expected, the Africanized honey bee quickly colonized the Peruvian lowlands east of the Andes but took some time the breach this formidable mountain range.  Once it appeared on the western side (Tumbes and Piura provinces), however, in the late 1970’s, it quickly migrated to the south toward Lima and north into Ecuador.  Nevertheless, the bee did not establish populations above 1,500 feet despite these being very close to lowland areas, which are highly saturated.¹⁵  Anecdotal information also suggests that Africanized honey bees in the highlands are not as defensively or otherwise behaviorally extreme as in the lowland tropics.

 

For those in temperate North America, the Argentine experience may be most representative.  It is known that two distinct populations of honey bees exist in that country, and there is also a hybrid transition zone between them.  In the more tropical northern regions, the honey bee population is highly Africanized.  As one moves south into the humid pampa, however, the European bee predominates.  Studies have shown that Africanized honey bees are as able to survive under as cold conditions as Europeans.  However, it is suggested that other environmental conditions including nest site availability, water and food sources, influenced by weather conditions, may be contributing if not major factors involved.¹⁶  This author’s experience in both Uruguay and Brazil reveals that beekeepers generally prefer European honey bees in the more temperate latitudes.  European bees appear to be more productive in spite of the fact that Africanized honey bees are more pest and predator tolerant.

 

Controversy over cold hardiness is the basis for very different maps drawn concerning the eventual distribution of the Africanized honey bee in North America.  One is by Drs. O. Taylor and M. Spivak. ¹⁷ Another map was developed by Dr. Alfred Dietz ¹⁸. 

 

Although the Africanized honey bee is not expected to become established in high latitude, temperate climates, the Canadian border remains closed to honey bee shipments, principally because of the presence of the bee in the neighboring southern United States.

 

It was thought that much of the riddle about where the Africanized honey bee would take up residence would be answered when the bees entered the United States.  However, it continues to take researchers and beekeepers by surprise.  The Africanized honey bee spread westward from Texas into the arid environments of southern New Mexico, Arizona and California fairly rapidly but has yet to inhabit most of the humid Gulf of Mexico coastline in the United States.  It is instructive to monitor the latest information from California showing that sightings are continuing to increase.¹⁹

 

The Africanized honey bee has not moved east and, over a decade after its arrival, a population has not been reported in Louisiana, Mississippi, Alabama nor Florida, where it was thought it might establish its highest concentration.  A provocative hypothesis is that an entrenched population of Varroa mites somehow has derailed the migration in North American humid environments.²⁰ 

 

Although a permanent population has not developed along the coast of the Gulf of Mexico, there continue to be isolated introductions of Africanized honey bees in that area.  These mostly are from ships.  In Florida, where extensive monitoring is occurring both at ports and along the border with Alabama (Perdido River), so far only one colony has been captured outside a port area.²¹  A record of sightings and other reports in the United States can be seen on the National Agricultural Pest Information System web site.²²

 

Managing the Africanized Honey Bee in the Americas:  Unpredictability

 

All countries invaded by the Africanized honey bee have gone through more or less a similar history to that of Brazil, related elsewhere in this publication.  Dr. Spivak concludes from the Costa Rican experience:

 

 “In all regions, there were beekeepers who were unwilling to modify their practices to adapt to new circumstances.  They soon experienced extreme stinging responses and high incidences of swarming and absconding.  Ultimately, these beekeepers abandoned their colonies.  Based on these occurrences, the idea was erroneously perpetuated that the entire population displayed uniform characteristics and that all bees were both dangerous to the public and undesirable from a management standpoint.

 

“When swarms and colonies from all areas were observed and assessed on an individual basis, however, they clearly displayed a wide range of behavioral characteristics.  It was the minority of colonies which were consistently unmanageable and extremely defensive.  Those beekeepers who were willing to requeen or kill such colonies and modify their management practices were able to work Africanized colonies profitably and with minimal danger to the beekeeper or public." ²³

 

Looking at the manageability of the Africanized honey bee in all environments it occupies, suggests that there is often no pattern that can be logically discerned among colonies.  Even the same colony can be highly manageable on one occasion, yet completely out of control the next.  Management of any system requires some degree of predictability.  That certainly is the case for European honey bees.  In the vast majority of cases, these insects can be counted on to take advantage of the same nectar resources, build their population numbers in regular fashion and otherwise behave in a consistent manner.  This is especially important not only for honey production, but commercial pollination and the one behavior beekeepers and the general public are most concerned about, defensive response. 

 

Adding to the general phenomena of unpredictability in managing Africanized bee colonies is the fact that swarms (reproductive and migratory) are completely different in temperament than established colonies.  Many novice beekeepers have gotten into trouble when they hived a swarm with low defensive behavior and later mistakenly thought they could also manipulate an established colony of the same bees using similar techniques. 

 

The general unpredictability of the Africanized honey bee leads to all kinds of management concerns.  Dr. Eric Mussen perhaps reported it best, quoting southern Texas beekeeper Bill Vanderput, "...25 percent more stings, 25 percent more work and 25 percent more sweat”. ²⁴

 

Since both Mexico and the United States were among the last countries in the Americas to experience the Africanized honey bee, they benefited enormously from information developed elsewhere as the migration advanced.   Mexico in particular has been extremely successful in providing information about the bee and preparing citizens for its arrival.  That country now has advanced bee breeding programs to help improve beekeeping conditions,²⁵ and sponsors a seminar each year attended by the beekeeping community.  This author was privileged to attend several, including the last in the City of Tepic, State of Nayarit.²⁶

 

With reference to productivity, there can also be unpredictability.  One problem is the paucity of studies.  How productive so-called “hybrids” between European and Africanized honey bees are continues to be controversial.  Drs. H.G. Hall and J. F. Harrison have provided the first (and so far only) solid data to show that African-European hybrids are at a disadvantage in their struggle for survival.  They measured the in-flight carbon dioxide output of 15 colonies of hybrids that Dr. Hall had established in Honduras with colleagues at the Escuela Agricola Panamericana. They also tested the Africanized and European parent colonies for comparison.

 

The results, as reported in the Apis newsletter²⁷ taken from May 20th issue of the international journal, Nature, show that Africanized bees are "souped up," they have higher metabolic capacities than European bees as predicted and observed.  However, the hybrids' energy-producing capacities were not intermediate, as originally thought, but only equivalent to or lower than those of Europeans.  The hybrids' lower metabolic rate may result in inferior flight performance or in other ways make them less adaptive in the tropics.  Certain enzymes in the mitochondria, where the oxygen is used and energy produced, require mitochondrial genes that come just from the mother, as well as nuclear genes that come from both the mother and the father.  Hall hypothesized that because Africanized and European bees have been separated for many thousands of years, the components of these enzymes may not be perfectly compatible. 

 

This information further confirms the prediction and subsequent observations that two distinct populations of bees exist in areas being colonized by Africanized bees.  The population of European managed bees is constantly under threat of being Africanized by the other, consisting of many wild Africanized colonies.  Because the Africanized mother lines are intact, however, the reverse is not true; very few European queens manage to produce drones which will hybridize with Africanized queens.  Finally, this suggests that hybrids produced in the wild are at an extreme disadvantage and their survival is questionable.

 

From a practical standpoint this means that to continue managing European stock in tropical areas, beekeepers must consistently requeen with European queens which must come from outside the area under siege by African bees.  To keep things in perspective, however, Dr. Hall suggests that some hybrids, which are managed properly by beekeepers, may actually be superior producers in certain situations.  This may be analagous to the current situation where those investigating mite resistance in various strains of bees suggest that some tradeoff may be necessary to keep a balance, in effect substituting superior honey production for less vulnerability to parasitic mites.

 

Identification of Africanized Honey Bees:  What’s in a Name?

 

The Africanized honey bee has been called many names during it’s occupation of the Americas.  Dr. Mark Winston has declared it the "pop insect" of the twentieth century with the name most people know as the “killer bee.”²⁸  The name “Brazilian bee” was given it first by a cadre of entomologists who authored a document entitled Final Report: Committee on the African Honey Bee:  “Since the strain of honey bee now spreading widely in South America is not pure Apis mellifera adansonii, but the result of greater or lesser hybridization followed by natural selection, it seems appropriate to call it the Brazilian honey bee.  The term African honey bee, as used in this report, refers to Apis mellifera adansonii as it occurs in Africa."²⁹   It is ironic given the amount of information that was to be acquired about this insect after the document was published that this report should be characterized as “final.”  In reality, it was only the beginning step in a remarkable and controversial scientific investigation that continues to this day.

 

Given the insect’s reputation, the term “Brazilian Bee” did not sit well with many in the country.  Brazilians were also upset about the conclusions in the report, believing that they did not reflect what was happening in the country at the time³⁰.  The name was also not accurate taxonomically speaking and has given way to either “African” or “Africanized” in the ensuing years.  Although originally thought to be a derivative of Apis mellifera adansonii from central Africa, as depicted in the “Final Report”, it is now recognized that the subspecies associated with the Africanized honey bee is the more southerly Apis mellifera scutellata. 

 

The naming problem exists to this day in scientific circles with some insisting that the best term for neotropical honey bees is “African” rather than “Africanized” and vice versa.  According to M. Winston, important biological implications result from such a nomenclatural dispute, with far-reaching applications in both management and control.  Two critical issues are: (1) how similar are bees in the Americas to African stock originally introduced into Brazil, and (2) how and to what extent has the Africanization of European bees occurred in Latin America?

 

Addressing the above questions, Dr. Winston says, is deceptively complex.  This well characterizes the conundrum beekeepers, regulators and others face in trying to identify the insect.  That’s because the behavior of Africanized honey bees is easy to distinguish from its European sisters.  Unfortunately, naming according to such a “subjective taxonomy” gives little information about how “European” or “African” a colony might be.³¹

 

The first effort to identify Africanized honey bees, and the one still in place for “official” diagnosis, is the classical one used in most biological classification (taxonomy), morphometrics.  This refers to measurements of body parts.  Two subclasses are univariate and multivariate analyses.  The former type has quickly given way to the latter, which is considered more accurate. 

 

A comprehensive publication on morphometrics and honey bees is by F. Ruttner.³²  Morphometric multivariate analysis for honey bees was further pioneered by H.  Daly and colleagues.  “When Africanized and European bees are compared on the basis of single characters, the variation in characters usually overlaps between groups.  An intermediate specimen or sample from a colony, therefore, cannot be identified at a high level of probability by a single character.” ³³

 

The method developed by Daly and colleagues employs twenty-five separate measurements.  These include “four linear measurements and ten angles between veins of the fore wing, number of hamuli (hooks that attach fore and hind wings), two linear measurements of the hind wing, four linear measurements of the hind leg, and four of the third sternum.”³⁴  Taken together these measurements are calculated to determine the probablility of Africanization.  As might be imagined, this is a tedious and time-consuming process. 

 

In an effort to make the technique available to regulatory officials and others, a version called Fast Africanized Bee Identification System or FABIS³⁵was developed at the USDA Baton Rouge Honey Bee Laboratory.³⁶  This involves a procedure that uses both fore wing length and weight of degastered bees (bees without abdomens).  Although named FABIS, the system as it is used really is better characterized as a fast European bee identification system.  This is because it discriminates European bees very well.  Comparing them with Africanized bees, on the other hand, is not well discriminated in the system (90% or less) and they must be subjected to further analysis, called the Universal System for Detecting Africanization (USDA-ID), which uses the full morphometrics technique.

 

Morphometrics has undergone a revolution in the last two decades.  “Now that the synthesis is established, the emphasis can shift to the application of morphometrics in various biological disciplines.”³⁷  Morphometrics-based identification has been criticized over the years for several reasons.  One is that the baseline of information to design the original system may have been too narrow or limited.  Another is that a great deal of measurement is prone to random error that can infiltrate the system.  Finally, environmental factors cannot be ruled out as influencing morphometrics.  Most telling perhaps is determination of bee size based on the cells they are reared in.  Thus, informal identification techniques in Latin America and elsewhere do not use the bees themselves, but cell size (the average width of ten cells found side by side in a comb).  Those bees having a cell width averaging 4.9 cm or less are declared Africanized, while those averaging 5.2 cm are determined to be European.

 

Other methods of identification have been suggested and employed.  One is characterizing allozymes (isozyme variants) using electrophoresis.  Especially important have been hexokinase and malate dehydrogenase.  According to Daly, "The use of allozymes to identify Africanized bees remains a viable option in need of improvement.”  Disadvantages include the need for specialized equipment, frozen samples and the fact that an adequate baseline of expected genotype frequencies in certain geographical areas has not been established.

 

The same might be said of using cuticular hydrocarbon analysis, which has also been proposed.  “Analyses of extractable hydrocarbons have demonstrated a number of differences in composition that are of potential use in identification.”³⁹  Frozen samples are not necessary; a single bee can be analyzed; and the process can be automated.  However, questions concerning the affects of bee age and potential hybridization remain.

 

Perhaps more focused than any method of honey bee discrimination is that provided by DNA research.  Studies pioneered by H. G. Hall show that DNA polymorphisms do exist that distinguish African from European honey bees.  Two types of DNA occur in biological species, allowing for differing kinds of analyses.  Whereas nuclear DNA is the result of the union of egg and sperm, mitochondrial DNA is only maternally inherited.  Again, detractors of this method point to small sample sizes and the need for expensive labor and equipment to perform routine analysis of honey bee samples.  Nevertheless, Dr. Hall states: “Results from DNA research provide a detailed view of African-European bee genetic relationship not possible with other methods.  Morphological and protein similarities have masked an underlying genetic variability only now being revealed by the bees’ DNA.”⁴⁰  The results of Dr. Hall’s research have convinced him that the term “Africanized” should not refer to the invading bees as it implies that they were originally European.  Thus, he prefers to call these bees “African.”

 

With new analyses and better interpretations of data, morphometrics may be in the process of being abandoned altogether.  Thus, according to H.R. Hepburn and S.E. Radloff, “There is an emerging paradigm shift from the morphometric mean, as the paramount statistic for defining subspecies, to that of the F statistic to characterise populations.”⁴¹  Independent geographic variation and non-morphometric knowledge creates problems in developing specific names that are biologically meaningful.  It seems that “One must choose between newfound biological meaningfulness and traditional taxonomic convenience, which entirely depends on the level of knowledge available about the extent of natural variation within a species.”⁴².  This author specifically asked Dr. Hepburn at the 2001 Apimondia meeting in Durban, South Africa about his concept of the Africanized honey bee in the Americas.  His reply was that they were “nasty, little bees from Pretoria,” which seemed to put him in the more African than Africanized camp.

 

In the final analysis, of course, none of the above discussion matters much to either the general public or the beekeeper who must deal daily with honey bees at the field level.  Both human populations are interested only in one characteristic, defensive behavior.  Few beekeepers enjoy managing over-defensive colonies.  As for the general public, it seems that Dr. Winston’s analysis continues to be correct.  “The media have largely ignored the intriguing natural history behind this insect’s proliferation and have paid scant attention to its economic impact.  Rather, attention has focused on shock stories and jokes, bad puns, and lurid tales of death by stinging.  As a result, the public’s impression of the Africanized honey bee goes far beyond it natural significance, and the normal fear in which people hold bees has become exaggerated to a ludicrous extent.”⁴³

 

Perhaps in response to the fact that the terms “African” and “Africanized” were so problematic, a new name is creeping into the literature, AHB.  This neutral acronym solves several problems; it defuses the naming problem and also reduces sensationalism.  Although its use seems to be on the rise in both the lay and popular press, AHB is meaningless with reference to the scientific millieu that surrounds these bees.  In the long run, therefore, it may confuse rather than clarify the naming problem.  In this publication, the name for these bees will continue to be “Africanized” as in its title.

 

Biological Basis for Africanization:  An Asymmetric Process

 

Perhaps the most important issue surrounding neotropical honey bees introduced into Brazil is that concerning the best way to describe the process of Africanization.  This is an important key to determining in the long run how to begin to deal with this insect.  Unfortunately, the arena remains obscured by lack of basic information and controversy.  An important contribution on this topic was provided by Dr. Glenn Hall at the University of Florida, who characterized the hybridization (Africanization) process as asymmetric in nature.  Thus, as noted elsewhere, Dr. Hall continues to use the terms “African” and “European” in his work to classify both Old and New World honey bees according to their continents of origin, limiting the name “Africanized” to European maternal lines hybridized to African males.⁴⁴

 

As noted in the pages of the APIS newsletter, as reported in the journal Nature (Hall and Muralidharan, v. 339: 211-213):

 

"Dr. Hall provides evidence that African honey bees are spread as a result of swarming by queens.  Of nineteen feral colonies collected in Mexico, all had typical African mitochondrial DNA.  Because only the African mother carries this kind of DNA, not one single generation of bees provided by European queens are represented in this sample.  In other words, the bees have maintained their African mitochondrial DNA even when it could have been lost by only one European queen providing offspring during their journey from Brazil through Central America into Mexico.

 

"The probability that all swarms collected by Dr. Hall would have African mitochondrial DNA should be small considering the fact that the bees are 5,000 miles and over 150 generations removed from their beginnings in Brazil.  In addition, the swarms were collected only fifteen months after arrival of the African bee in the area of Mexico where collections took place, and the region still has many managed colonies of European honey bees.  That every single sample had African mitochondrial DNA is extraordinary, so much so that it warranted publication in Nature.  A companion paper authored by D. Smith (Smith, Taylor and Brown, vol. 338: 213-215) offers independent verification of Dr. Hall's results.  Of a mixture of colonies and swarms from Brazil, Venezuela and Mexico, 59 out of 61 had African type mitochondrial DNA. In conclusion, the author states: '...an essentially African population is expanding...through migration and colonization of new territory by African females.'

 

"In a comment on the above papers in the same journal, Dr. Robert Page, University of California at Davis, said: 'The reported demonstration of high frequencies of African-type mitochondria in honey-bee populations in South and Central America, together with Mexico, suggests an unbroken African maternal lineage for most feral bees observed.'

 

"The interpretation of the above information is that drones play a much smaller role in the propagation of African bees in the tropics than do queens.  If drones were the prime force causing Africanization of European bees in places like Venezuela, Costa Rica and Mexico, then there should be a greater mixture of African/European mitochondrial DNA than the above studies show.  The practical significance of this is that breeding programs in the tropics relying on European drones to ‘dilute’ African traits will not have much effect because (1) there are so few European drones to mate with, and (2) the African mother lines are continuing to produce numbers of African drones.  Hybridization between European and African bees, therefore is asymmetric in the tropics, favoring African bees. This has been observed in all places so far colonized by African bees in the Americas.

 

"Part and parcel of this interpretation is the prediction that two populations of bees exist in areas being colonized by African bees.  One population of European managed bees is constantly under threat of being Africanized by the great many wild African colonies in the area.  Because the African mother lines are intact, however, the reverse is not true; very few European queens manage to produce drones which will hybridize with African queens.  This means that to continue managing European stock, beekeepers must consistently requeen with European queens which must come from outside the area under siege by African bees.  This is the scenario many beekeepers will face, especially in the southern U.S., with the arrival of the African bee.

 

"The above interpretation is not without detractors.  Although there have and continue to be many words said at bee meetings and other gatherings concerning the potential hybridization between European and African bees in the tropics, no reviewed publications exist to refute the findings reported above.

 

According to Dr. Hall, DNA findings to date can be easily summarized.

 

1. The migrating force of African bees consists of unbroken African mother lines spreading as feral swarms.  Evidence for this is found in results of the mitochondrial DNA studies mentioned above.

 

2. In the tropics, African queens in feral swarms have hybridized only to a small extent, if at all, with European drones.  Evidence for this is found in nuclear DNA study.

 

3. European queens in tropical apiaries extensively hybridize with African drones, and can be called Africanized.

 

Therefore, as Dr. Hall pointed out in his report on DNA research funded partially by the Florida State Beekeepers Association in a recent association newsletter: ‘As the bees move north into temperate regions, where European bees have advantages, increasing amounts of hybridization should take place.  African behavior among feral bees should become reduced. European and African bees will probably establish a hybrid boundary across the southern U.S., as Dr. Orley Taylor and Dr. Marla Spivak, at the University. of Kansas, forecasted years ago. However, even in areas such as Florida, where European bees do survive well, feral hybrids may also survive to a greater extent than they do in the tropics." ⁴⁵

 

Dr. Hall’s view of asymmetric hybridization remains controversial.  Mostly it seems to boil down to a matter of how much hybridization one is willing to accept and/or can prove.  For example, as R. Helmich and T. Rinderer state,

 

“It is important to understand that Africanized bees are hybrids.  The processes of Africanization resist changes in gene frequency toward the European types and yet there is sufficient mating between Africanized and European bees that extensive measurable hybridization exists throughout the Africanized population.  Since Africanized bees only resist cross breeding but are not insulated from it, the processes of Africanization are imperfect.  Consequently, (1) hybrid populations form throughout the range of bees in the New World, (2) programs by agencies, groups or individual beekeepers that promote mitigation of Africanization through hybridization are likely to be successful, and (3) variation derived from hybridization can provide a good basis for the development of quality strains using selection programs throughout the New World.”⁴⁶

 

In this context, information is needed on how hybrids interact and behave.  G. Hall at the University of Florida and O.  Taylor, University of Kansas, teamed up at the 1993 Florida State Beekeepers Association meeting in West Palm Beach to discuss hybrid honey bee biology as reported in the Apis newsletter⁴⁷.  Dr. Taylor's studies of queen and worker development time in Mexico, Dr. Hall's investigations of metabolic rates in collaboration with Dr. Harrison of Arizona State University, and analyses of honey production at the Escuela Agricola Panamericana (Zamorano) in Honduras all show similar patterns.

 

African mother lines generally propagate better-performing hybrid offspring than do Europeans in the first generation (called F1 by geneticists), although European mother lines do produce viable stock. In succeeding generations (back crosses), both African and European mother lines become progressively less vigorous. However, the European mother lines do so to a much greater degree.

 

Thus, instead of uniform hybridization between the two populations, these investigations suggest a parental influence skewed towards the African side in the American tropics. It was stressed that these dynamics have been studied in mostly feral or wild bee populations. Colony management (helping them become more competitive) by beekeepers in the honey production study appeared to help hybrid stock compensate.  In one African-European cross, for example, while metabolic rates were lower, suggesting a less productive bee, honey production was almost the same level as that of the maternal African parent.

 

Dr. Taylor said that in the tropics, a zone of temporary hybridization may first appear along the feral African bee invading front, but that population becomes more African-like over time. How much of a hybrid African-European feral population will eventually persist across the southern tier of states in the United States, as is now found in northern Argentina, he stated, is unknown at present.

 

According to Dr. Hall, these studies collectively reveal that far more attention may have to be paid to the contribution of the African mother line when developing hybrid honey bees for beekeeper use in the southern United States.  Simply saturating an area with European drones or requeening with European certified stock may not be enough to keep the feral African-derived population's influence at bay.  In the final analysis, the only way to answer many of these questions is to intensively study the hybrid biology of African and European bees where they collide.

 

The term hybridization, however, may mean little when it comes to describing the Africanized bee with reference how closely are Africanized honey bees related to their African ancestors.  According to Dr. D. Fletcher, genetically “pure” African Apis mellifera scutellata may not have been imported into Brazil in the first place, and although overwhelmingly African in behavior, or there would have been no “Africanized bee problem,” there is a high probability that African bees in Mexico differ from African populations they came from.  Although hybridization is a possibility, other explanations cannot be ruled out.  These include:

 

1.  The founder effect:  That the genetic material introduced was limited and was not representative of the original population as a whole.

 

2.  Selection in the tropics:   That the transvaal A. m. scutellata are not nearly as tropical as those of Central Africa.  However, they will have crossed the entire tropics from north to south, a 33-year journey. It is hard not to conclude that the African bees now at the tropic of cancer are more tropical genotypically and phenotypically than those that left Pretoria.

 

3.  Attrition of patrilines:  Few patrilines would survive the initial stages of developing a feral African population.  Dr. Fletcher did not mention if these are European patrilines.

 

4.  Attrition of matrilines:  If all 26 original matrilines survived, there still would be a relatively small sample of the genes present in the African population.

 

Thus, Dr. Fletcher concludes, “There is strong empirical and deductive evidence to suggest that the African bees that will enter the United States differ in many important characteristics from those of their parental population in southern Africa.  These differences, of course, are of degree rather than kind (this author's emphasis).  Whatever genetic changes have occurred, many are detrimental from the practical standpoint of the North American beekeeper.  The question is, what can be done about this?” ⁴⁸

 

Plans to Deal With the Africanized Honey Bee: Latin America

 

Humans have conjured up plans to deal with the Africanized honey bee ever since it was first introduced.  It took experiences in Brazil, the Guianas and Venezuela, however, to begin to understand the real problems associated with this insect.  As noted above, behaviors characterizing Africanized bees, especially defense of the nest, were erratic and not predictable.  In addition, a huge feral (wild) population of bees built up in the tropics where there had not been much honey bee presence before.  Humans were not used to these bees in their environment.  Africanized bees were also found in nest sites in places European bees would not inhabit, confounding even those who had some bee management experience.  These included ground and open-air nests in trees.  Many stinging incidents were the results of this kind of nesting behavior.  A North American example is that almost every underground water-metering device in the city of Tucson, Arizona now is reported to have or predicted to have a nest of these bees in the future⁴⁹.  Migrating swarms are also common, and more and more bees are found in human conveyances like heavy trucks, railroad cars and ships.

 

Immediate concerns in areas invaded by the bee are the changes the Africanized honey bee will demand of a local beekeeping industry and public safety.  In essence the bees will not change; the people dealing with these insects much adapt their behavior. 

 

There is no question that most regions in South America where the bees have migrated have suffered large reductions in honey production.  Beekeepers using European honey bees were either not prepared nor willing to put up with the erratic behavior of Africanized colonies.  In addition, Africanized honey bees were generally thought to be less productive.  However, some colonies produced large quantities of honey.  The majority, though, appeared to be marginal in size and prone to swarming, reducing their productivity.  The total reduction in honey crops wherever these bees were first found often led to the generalization that they were “poor” honey producers.  This is not easy to judge, since honey reduction on a large-scale may not necessarily be a result of poor colony productivity but the fact that many beekeepers simply quit the activity, and so beekeeping as a whole declined.

 

The Brazilian Experience

 

Brazil is clearly ahead of the pack when it comes to effectively using the  Africanized honey bee.  Ever since the early 1980s, researchers and beekeepers in the country have continued to state that these insects are the best thing to have happened to Brazilian beekeeping productivity.  Decades later it is difficult to argue with this conclusion as a new much-improved version of Brazilian apiculture has been invented based on this insect.

 

Although the European honey bee had been introduced two centuries before, wild nests were rare and the craft of beekeeping was practiced by only a few dedicated persons, who often kept colonies in mostly rustic, fixed-comb hives, not of the modern moveable-frame Langstroth design.  This changed greatly with introduction of the Africanized honey according to Eng. Agr. Paulo Gustavo Sommer,

 

“Introduction of the Africanized honey bee in 1956, however, was a seminal turning point.  The result of twenty-six queens escaping confinement in Rio Claro in the state of São Paulo, according to Eng Sommer, was a huge expansion of Africanized bees in the wild.  The insects quickly saturated much of tropical Brazil and migrated into neighboring countries.  The result was most immediately felt, however, among beekeepers, as the defensive nature of their colonies, usually kept in rustic hives, increased dramatically.  This in fact resulted in complete destruction of beekeeping as it was then known with European bees.

 

“Rising phoenix-like from these ashes, however, has come a robust commercial activity based on Africanized bees, according to Eng. Sommer.  Over ninety percent of Brazilian colonies are now managed in modern moveable-frame Langstroth equipment.  A growth rate of 4.5 percent per year in honey production since 1985 has resulted in production of 35,000 tons in 1996, rivaling nearby Uruguay.  And there seems little reason, Eng. Sommer concluded, that a level of 200,000 tons per year could not be reached in the future.

 

“Besides the Langstroth hive, other modifications in beekeeping technique have been made in Brazil to accommodate the Africanized honey bee according to Eng. Sommer.  Wax foundation has been adjusted to the bee's size, somewhat smaller than the European bee.  The increased defensive behavior required a different smoking technique.  Huge numbers of migratory and reproductive swarms nesting in many places and the possibility of them stinging the general public has presented challenges and opportunities in trapping bees.  Finally, beekeepers have actively selected their bees to eliminate many objectionable behaviors for which this bee is generally known."⁵⁰

 

“Among the most important attributes of the Africanized bee in Brazil are:

 

1. Increased hygienic behavior.

2. More efficient foraging.

3. Greater natural resistance against pests and diseases.

4. Superior pollination in intensively cultivated fields.

5. Stronger genetic dominance.

5. Increased defensive and swarming behavior.

 

"The latter behaviors would seem to be counterproductive, but proof that they are controllable is found in the present condition of Brazil's beekeeping industry. As part of this activity, Eng. Sommer, concluded, the country can count hundreds of short courses, symposiums, seminars and many national congresses."⁵¹

 

The scientific energy engendered is also apparent. The proceeding