Although the African (above left) is slightly smaller than its European counterpart (right), the two belong to the same species, and only a highly skilled expert using sophisticated techniques can tell them apart. Africanired colonies are easily aroused, a trait that has given them a reputation as “killer .” (Photos by E.S. Ross)

The Af ricanized : ahead of schedule

Norman E. Gary 13 Howell V. Daly 0 Sarah Locke 0 Margaret Race

The bee’s early arrival added urgency to efforts to devise effective controls

Theaccidental discovery in June 1985 struction of any wild honey bee colonies Across this range, the races differ little in of a wild colony of Africanized honey bees found in the area. Agency officials and appearance or structure, but do differ sig- in Lost Hills, near Bakersfield, was un- scientists are cautiously optimistic that nificantly in behavior. Over the years, the welcome news for California apiculturists their actions, combined with genetic dilu- relatively gentle European races were and growers. The bee’s appearance in tion, will prevent the further spread and taken to other continents for use by bee- California was not a complete surprise, premature establishment of the African- keepers. The honey bees in both North and but it was not expected to arrive until ized bee in the continental . originated from European sometime in the 1990s after gradual mi- At the time this article was written, five sources, with the Italian race, Apis melli- gration and spread from its present north- commercial and three wild colonies of fera ligustica, the most favored by com- ernmost location in Honduras, Central Africanized bees had been found and de- mercial beekeepers. America. The bee’s early arrival was stroyed, but additional finds were expect- A race of African bees, Apis mellifera probably caused by the unintentional im- ed. All finds to date are of mixed parent- scutellata, was introduced into in portation of a wild colony inside drilling age, indicating that the common 1956 in an effort to breed a bee that would equipment shipped from South America European bee in California is interbreed- produce more honey in the tropics. Euro- to the oil fields in Kern County, or from a ing with the introduced , pean bees are adapted to temperate cli- truckload of imported cargo. and suggesting that genetic dilution is oc- mates and do not perform well in tropical As additional colonies were found dur- curring. and subtropical climates, especially in the ing the summer, California’s Department lowlands. As part of a breeding program of Food and Agriculture intensified its History to eliminate or minimize the ’s monitoring and eradication efforts, im- The honey bee, Apis mellifera, ranges undesirable characteristics while retain- posed a holding action on the movement from northern Europe to the southern tip ing its honey-producing traits, Brazilian of commercial hives, and ordered the de- of Africa, and eastward into western Asia. researchers brought 47 queens from Afri-

4 CALIFORNIA AGRICULTURE, NOVEMBER-DECEMBER 1985 ca to Rio Claro in the state of SoPaulo, Brazil. The bees were introduced into colonies equipped with double queen ex- cluders covering the entrances to prevent their escape. In 1957, a visiting beekeep- er, not understanding the strict precau- tions against the escape of queens and drones, removed the queen excluders from 35 hives when he noticed an accu- mulation of pollen at the entrances. Be- fore his action was discovered, 26 colonies had swarmed or absconded. After several years, it became appar- ent that the strain of African bees was not being diluted by the established European bee population but that European colonies were becoming Africanized. The African bee apparently hybridized to a limited de- gree with European stock, leading to a strain that genetically is still almost iden- tical to the original African bee but is re- ferred to as the Africanized or “killer” bee. Various Brazilian attempts between 1963 and 1972 to dilute the Africanized bees by requeening the most aggressive colonies with Italian bees had only limited success. Africanized bees quickly supplanted European stock, expanding their range 200 to 300 miles a year from the original epicenter in Brazil, and now have reached Honduras. Studies in Venezuela, Colom- bia, and found the bee has retained virtually all of its African The combs distinguish the Africanized from the European bee; Africanired worker Cells characteristics as it has spread. in natural comb (bottom) are smaller than the comb cells of European honey bees. The bees are expected to arrive in Tex- Africanized bees develop faster and live shorter lives than European bees. Some as around 1988-90 and to become estab- apiculturists believe the Africanired bee is a better honey producer. lished from to California in areas with adequate nectar, pollen, and nest Africanized bees reportedly have a longer rather than walking in as European bees sites, and suitable winter conditions. life expectancy than those of European do. When compared with European honey bees, suggesting that they may be more bees, African bees in Africa foraged at Biology/natural history successful at replacing queens than are lower temperatures and light intensities, No single structure distinguishes Afri- European colonies. foraged in the rain, and foraged earlier can or Africanized bees from European Africanized bees nest in cavities found and later during the day. bees. Differences are a matter of degree in the ground, in termite mounds, under In some areas, Africanized bees reput- and not of kind. buildings, in barrels, and in old cars. edly produce more honey per colony than Africanized worker and queen bees on Sometimes they even construct combs in European bees, although there is conflict- average are slightly smaller than workers open exposed nests. They appear to prefer ing information on the subject. Commer- and queens of the European races. Afri- somewhat larger cavities for their nests cial honey production in northern Brazil canized worker cells in natural comb are than European bees do, even though they dropped dramatically after many bee- also smaller in average diameter. Color is may only partially fill them with comb. keepers were forced out of business by the highly variable, but most Africanized European honey bees select smaller cav- bees’ temperament, but efforts to im- workers have yellow abdominal bands. ities that are large enough to store winter prove techniques have Development time from egg to adult is food reserves. Both races maintain simi- changed this. shorter for Africanized than European lar brood nest temperatures. The best known characteristic of Afri- workers (18 to 20 days versus 21 days). Originally it was assumed that Afri- canized bees is their extreme defensive- During the tropical dry season when flo- canized bees were unable to overwinter in ness, usually misinterpreted as aggres- ral sources are abundant and colonies be- cold climates, but recent studies in Argen- siveness. Colonies are extremely sensitive gin a rapid population increase before tina, as yet unpublished, indicate that they to disturbances, such as vibration, foreign , Africanized workers live 12 to may be able to overwinter much farther odors, and movements, and the bees re- 18 days compared with 32 to 35 days for north in the United States than was pre- spond faster, in much greater numbers, European worker bees. viously supposed. and with more stinging than European Colony growth of Africanized bees is Africanized bees are more excitable bees. When disturbed, they follow and per- reported to be rapid, and the annual egg- and active than European bees, flying in sistently sting and people hun- laying rate is approximately double that quicker and more erratic patterns and of- dreds of yards from their colony. Recov- of European bees. Individual colonies of ten flying directly into the hive entrance ery time after disturbance is about 30

CALIFORNIA AGRICULTURE, NOVEMBER-DECEMBER 1985 5 Africanired bees show little discriminationin where they build their nests: in the ground, in termite mounds, under buildings, in exposed areas, even in old cars. Norman Gary, UC bee researcher, checks the nest of the first Africanired bee colony discovered in the United States, near Lost Hills, California, in June 1985. The well-established nest contained approximately 20 combs. minutes for Africanized bees compared ter. Absconding differs from reproductive with 3 minutes for European bees. Re- swarming in that the colony produces no Identification searchers concluded that Africanized bees new queens, and all the workers and There are two levels of identification are up to ten times more active in sting- drones leave the nest with the mated of Africanized honey bees, one for detect- ing than European bees. queen. European colonies rarely abscond; ing their presence, and the other for de- Individual Africanized bee stings are Africanized bees do so regularly. Ab- tecting varying degrees of hybridization no different from European stings. No sconding rates for honey bees in tropical between Africanized and European bees, significant chemical differences between Africa are 15 to 30 percent a year, but can once they coexist. Because African and of Africanized and European bees be up to 100 percent in some areas. European honey bees are two races of the are known. The difference in stinging epi- In Brazil, wild Africanized bees are same species, the differences between sodes is due to the sheer number of sting- abundant. In one study, an average of 107 them and their hybrids are quantitative ing Africanized bees. A substantial num- colonies per square kilometer were found rather than qualitative. The problem of ber of cases have been reported in which in a savanna region. Wild European bees identification is complicated by the multi- animals and people have been severely or are practically nonexistent in the tropics. ple matings of honey bee queens, which fatally stung because of the abundance High densities of wild Africanized colo- fertilize eggs with stored sperm from up and special behavioral characteristics of nies produce large numbers of drones that to 17 drones. Thus, pure and bees Africanized bees. It should be noted that may mate with virgin European queens frequently commingle within a single some of these incidents, particularly those from colonies in commercial . colony. Drones and workers also “drift” involving hypersensitive people, could There appears to be some degree of from one colony to another where hives have occurred even if European bees had reproductive isolation between African- are close together in commercial api- been involved. ized and European honey bees. Research- aries, creating sampling problems. Honey bee colonies reproduce by ers have several possible explanations, in- At present there are basically four swarming during periods of rich re- cluding greater mating flight distances identification methods to separate Afri- sources. During reproductive swarming, a from the colonies by European queens canized and European honey bees. These significant portion of the workers and than European drones. While this pre- are (1) electrophoresis or isoelectric fo- drones, along with the mated queen, leave vents inbreeding to drones from the same cusing of proteins in bee blood, a laborato- the colony and establish a new colony colony, it favors greater encounters with ry technique to detect inherited differ- elsewhere. Several afterswarms, each wild Africanized drones in areas where ences in enzymes within organisms, (2) containing new virgin queens, may also wild Africanized bees predominate. Slight evaluation of observable traits such as issue from the same colony. In the tropics, differences between the two races in the cell size, colony defensive response and Africanized honey bee colonies swarm time of day when flights occur may bee weight, (3) gas chromatographic anal- three to four times annually. By compari- also contribute to reproductive isolation ysis to determine the kinds of hydrocar- son, in temperate , both by increasing the probability that Afri- bons in the bees’ cuticle, and (4) multivar- wild and managed European bees swarm canized queens will encounter Africanized iate morphometric analysis, a statistical- once or twice annually. drones during their respective mating computer analysis to distinguish races of Owing to adverse conditions, distur- flights. Also, European colonies may pro- bees based on measurements of many dif- bances, or rapid colony growth in inad- duce fewer drones owing to the presence ferent body parts. For various reasons, equate space, Africanized bees frequently of invading Africanized drones and severe none of these methods is fully satisfac- abscond and migrate to a new nest near competition with Africanized colonies for tory, but the morphometric method has better sources of nectar, pollen, and wa- limited nectar and pollen resources. been most frequently tested and used.

6 CALIFORNIA AGRICULTURE, NOVEMBER-DECEMBER 1985 This identification method was developed must return to their colonies after their hives to make apiaries unwelcome in at UC Berkeley, with some modifications mating flights. Individual European fields and orchards because of the sting by the US. Department of Agriculture drones released in an area would die of hazard. Assuming pure European stock (USDA), and then employed in the recent starvation within several hours, because can still be produced in California after infestation in Kern County. they would have no home colony to which Africanized bees become established, it is Other methods of identification are to return. unknown whether European bees will be needed to improve the accuracy of evalu- European bee colonies managed for able to compete with a potentially high ating the degrees of hybridization and to drone production would have to be distrib- density of wild Africanized bees foraging monitor the purity of breeding stock in the uted throughout a given area. However, on the limited pollen and nectar sources. future. because of the partial reproductive isola- Also, Africanized bees could have a se- tion caused by differences in drone mat- rious effect on the commercial beekeep- Control methods ing flight times, this method would be ing industry for queen and package bee Because Africanized and European most effective if a genetic line of Europe- production as well as honey production. honey bees are the same species, there is an drones were to be bred to fly at times California ranks eighth in the nation in little possibility that selective control similar to Africanized drones. honey production. methods can be developed. Genetic control. Genetic manipula- Another potential problem for US. Eradication. Where Africanized honey tion appears to be a promising approach. beekeeping is the introduction, by incom- bees are firmly established in the tropics, Because Africanized and European bees ing Africanized swarms from South their very high reproductive rate, the long are the same species, Africanized honey America, of the mite Varroa jacobsoni, a distance migration of swarms, their par- bees should be viewed as pest genes rath- parasite of honey bees. This destructive tial reproductive isolation, and their resil- er than a typical pest species. All bees in a mite thrives in all climates and could ience to known control techniques have colony are the progeny of the single spread throughout the United States and made attempts to eradicate them unsuc- queen. Through artificial insemination Canada. cessful. the queen’s genetic makeup, and therefore The public would most likely encoun- Pesticides. Frequent use of pesticides the colony’s genetic makeup, can be con- ter Africanized bees in the form of wild over extensive areas would not be accept- trolled. Beekeepers therefore can manip- colonies and swarms in urban and subur- able because of the potentially severe eco- ulate the stock in their colonies by replac- ban as well as rural areas. Increased inci- logical impact on nontarget organisms, ing the queen yearly or when undesirable dences of stinging would probably occur the resilience of honey bee colonies (as colony traits appear. but might be reduced significantly by the opposed to the susceptibility of individual It should also be possible to work with- establishment of public awareness pro- foragers away from the hive) to pesti- in the Africanized bee gene pool to select grams, as well as continuous, permanent cides, the reproductive and migratory be- more gentle strains of Africanized bees programs by public agencies to control havior of Africanized bees, and the politi- that would be easier to manage. New wild colonies. cal, legal, and economic problems technology for quickly locating and de- Research priorities for the immediate associated with such a program. Aerial stroying the old queen in each colony (nec- future are to continue the development of application would be ineffective, because essary if bees are to accept a new queen) more sophisticated identification methods Africanized bees nest in cavities that has recently been developed at UC Davis, and to initiate, as quickly as possible, a would not be hit by the sprays. making it economically feasible to find “crash” genetics research program on Biological agents. There are no and replace queens in commercial bee- honey bees, European bee breeding stock known biological agents, such as patho- keeping operations. must be protected as long as possible and gens or parasites, that would control or selection of desirable traits from African reduce populations of Africanized honey Conclusions bees must be a high priority. bees without also seriously damaging the Africanized bees are a potentially seri- The summer’s outbreak brought a re- economically important European bees. ous threat to the pollination of many agri- newed sense of urgency to planning for Trap and bait hives. Aside from de- cultural crops. Nationwide, the total val- the anticipated natural spread of the bees tecting and monitoring any early intro- ue of honey bee pollination to agriculture into California. To date, the Africanized ductions preceding a large-scale migra- has been estimated at $20 billion annual- bee has not been eradicated from any tion, the use of bait hives to control ly. In California, more than 600,000 com- area in which it has become established. Africanized bees appears impractical be- mercially managed pollinate 40 The Africanized bee has the potential to cause of (1) the potential of swarms to crops, valued at $4 billion annually and have a devastating impact on California’s move long distances despite available including fruits, melons, berries, , agricultural industry and to threaten pub- nest sites, migrating many miles through citrus, seed crops for vegetables, and for- lic health and safety. All indications are and beyond trap zones, perhaps within a age crops such as alfalfa. that we can expect a long-term, if not per- few hours, (2) the numbers needed to cov- On a bee-by-bee basis, when foraging manent, battle to gain and maintain ge- er thousands of square miles, and the lo- in the field, Africanized bees may polli- netic control and to continue efforts to im- gistics of distribution, even if they were nate as effectively as European bees. prove honey bee stock to fit the changing effective, (3) the unknowns associated Their colonies, however, are not manage- needs of agriculture. with the identification, synthesis, and con- able as commercial pollination units un- Ironically, the Africanized bee breed- trolled release of pheromones used to at- der California conditions, with the vast ing program that was envisioned in Brazil tract swarms, and (4) the expense of such acreages of crops interspersed with many years ago now must be conducted in a program. roads, livestock, and people, and especial- California. Release of European drones. The ly the need to transport hives frequently Norman E. Gary is Professor, Department of Ento- massive release of European drones by truck from area to area. mology, University of California, Davis; Howell V. would be ineffective in diluting African- Even with continual diligence by com- Daly is Professor, Department ofEntomologica1Sci- mercial beekeepers to maintain strict ge- ences, UC Berkeley; Sarah Locke is a graduate stu- ized bee genes in an area. Honey bee dent in the Department of Entomology, UC Davis; drones are fed and maintained by worker netic control of their European colonies, and Margaret Race is Research Analyst, Agricultur- bees within their respective colonies and wild Africanized bees may occupy enough al Experiment Station.

CALIFORNIA AGRICULTURE, NOVEMBER-DECEMBER 1985 7