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Peer-reviewed Article

Living with the Africanized bee: Sinaloan beekeepers adapt pollination to Africanized bees

authors

Francis Ratnieks, UC Riverside
P. Kirk Visscher, UC Riverside

publication information

California Agriculture 50(4):24-28. DOI: 10.3733/ca.v050n04p24. July-August 1996.

author affiliations

F. Ratnieks was a postdoctoral associate in Entomology at UC Riverside and now is Lecturer, University of Sheffield, England; P.K. Visscher is Entomologist, Department of Entomology, UC Riverside;

abstract

Africanized honeybees have become well established in Sinaloa, Mexico, which has large-scale agriculture similar to California's. Beekeepers in Sinaloa have adapted their management practices to continue to provide pollination of crops. As Africanized bees become established in California, similar adjustments can probably maintain effective honeybee pollination of California crops.

full text

Honeybee hives in place for pollination of squash. These bees are kept in extra-large hive bodies, about equivalent to pollination units in California.

Africanized honeybees have recently arrived in California. They were first detected in the fall of 1994, near Blythe. As of April 1996 there have been 21 colonies identified as Africanized, mostly in Imperial County. These newcomers are worrisome both for California beekeepers and for growers who rely on honeybees for crop pollination. California crops requiring bee pollination include almond, avocado, plum, prune, cherry, apple and other tree crops, cucumbers, melons, squash, alfalfa, vegetable seeds and kiwi fruit. The annual value of these crops is several billion dollars. To ensure adequate pollination, California growers rent about 1.4 million hives each year, accounting for approximately half of all U.S. hive rentals. About half of pollination rentals in California are for almonds alone.

The extent to which California will be colonized by Africanized bees, and the extent to which managed bee hives will be affected is unknown. However, by the end of July 1996, 30 colonies of Africanized bees had been verified in Southern California. In areas that do become colonized with Africanized bees, some changes in apicultural and agricultural practices will be necessary, and it will take a few years for beekeepers, growers and the public to adjust to the new situation.

One way of hastening the adjustment process is to take advantage of knowledge acquired by beekeepers and growers in Mexico, where Africanized bees have been present for nearly 10 years. We visited beekeepers in Sinaloa, a part of Mexico where these professionals derive most of their income from pollination rentals — as do California beekeepers — and where the agricultural system is similar to California's agricultural valleys. (The main income for most beekeepers in Mexico — and most U.S. beekeepers — is from honey sales.) We visited in January 1995 and December 1991. During these visits we visited apiaries and farms where hives were being rented, and spoke in Spanish with four beekeepers who account for the majority of pollination rentals in the area. We also interviewed a Mexican department of agriculture (SARH) official responsible for Africanized-bee-awareness programs in Sinaloa.

The information we gathered shows that bee pollination of crops can continue in an area that has been fully colonized by Africanized bees. This suggests that if California becomes extensively colonized, beekeepers and growers can make satisfactory adjustments through new management practices discussed below.

Agriculture in Sinaloa

Background

The state of Sinaloa lies on the west coast of Mexico, beside the Pacific Ocean and the Gulf of California. The Western Sierra Madre mountain range forms the eastern boundary. The state extends about 200 miles north and 100 miles south of the Tropic of Cancer. The main agricultural area is the flat coastal plain, about 200 miles by 40 miles, located in the northern two-thirds of the state and extending from Culiacan to Los Mochis. This zone is connected by about 550 miles of four-lane highway to Nogales, Arizona, the main entry point for its exports to the United States. The Sinaloa climate is tropical and dry, with three rainy months during the summer. Numerous dams in the mountains store irrigation water.

These colonies in a large cucumber field are hybrids: their queens are European, but have mated with Africanized drones. They are more defensive than similar European colonies, but not as fierce as Africanized colonies. Even while the hives were being opened here, workers were able to work nearby.

Crops

In appearance, the Sinaloa coastal plain is similar to California's Central Valley. In both areas, crops are grown near sea level in large irrigated fields using mechanized methods. In contrast to the Central Valley, row crops are grown year round and there are fewer tree and vine crops.

Sinaloa provides many of the fresh vegetables Americans eat during the winter, particularly tomatoes, cucumbers, squash, eggplant and peppers. It also grows numerous other crops, such as corn, wheat, beans, garbanzos, sesame, cardamom, mango, avocado, citrus and banana. According to Sinaloa's local newspaper, about 500 truckloads of vegetables crossed the U.S. border in Nogales each day in January. This illustrates the large scale of agriculture in Sinaloa.

Pollination needs

Many crops in Sinaloa, as in California, require growers to rent bee hives to ensure pollination. Without adequate pollination, yields are reduced and the vegetables may be too small or misshapen for the U.S. market. Cucumbers account for 90% of all hive rentals. The introduction of hybrid cucumbers with few male flowers has led to an increase in optimum hive density from 7 to 14 hives per acre (from 3 to 6 hives per hectare) on farms with progressive managers. Hives are also rented for various squashes, melons and eggplant. In all these crops 3 to 6 hives per hectare are used, depending on the grower. Each year there are about 30,000 hive rentals (some hives are rented more than once). About half of these rentals were supplied by Mr. Javier Pompa, one of the beekeepers we visited and president of the state beekeepers association. The rental fee for the last few years has been 80 new pesos, or $23 (exchange rate prior to recent devaluation of the peso). Rentals last 30 to 40 days, except for eggplant, which lasts twice as long and is calculated as two rentals. Bees are often killed by pesticides, much of the damage coming from daytime spraying. Beekeepers are not compensated for these kills, nor for the theft of hives. However, they are compensated if hives are damaged by farm machinery.

Feral Africanized bee colonies made nests in the windows visible in this hospital. These unmanaged Africanized bees pose a threat and there have been stinging deaths.

AHB history in Sinaloa

The Africanized honeybee (AHB) arrived in Sinaloa around 1990. In December 1991, Mr. Pompa told us the Africanized bees had not yet had an impact on beekeeping because most colonies still had their original European queens. The impact of Africanization was felt over the next few years as the hives managed by beekeepers became, to a greater or lesser extent, Africanized.

The Africanization process in Sinaloa was dramatic, with vast numbers of swarms invading the area. As an indication of the number of swarms arriving, public authorities in the city of Culiacan (population approximately 500,000) eliminated approximately 1,700 swarms and feral colonies during 1994, according to a Mexican department of agriculture (SARH) official. One church had over 40 feral colonies. A beekeeper with five apiaries near the small town of San Ignacio paid a bounty for the elimination of feral nests in his area; 650 feral nests were found within a few miles of his apiaries.

As in other parts of Latin America, the Africanized bee has lived up to its nickname “killer bee,” with 18 fatalities so far in Sinaloa, according to an SARH official. Most of the victims were elderly and unable to outrun the bees. In many cases they were killed by fewer than 100 stings, a number that would be painful but not life-threatening to a younger adult. It is important to note that all of these deaths were caused by feral colonies or possibly swarms. None was caused by bees managed by beekeepers.

Economic effect on beekeepers

Beekeepers have been economically affected by the arrival of the Africanized honeybee, but have not been put out of business. The three main costs to beekeepers have been:

However, the arrival of the Africanized bee has hardly affected Mr. Pompa's gross income from pollination rental because he has been able to provide sufficient colonies of hybrid bees to fulfill his contracts. Our interview data suggest that in Sinaloa, beekeepers' net income has been most affected by reduced honey production, although higher wages, and absconding costs are factors as well. We did not collect sufficient data to determine what the change in net income has been. On the plus side, Mr. Pompa and Mr. Sosa report that the hybrid bees they now use are less affected by brood diseases such as American and European foulbrood, and are less subject to theft.

Changes in beekeeping practices

In order to keep and manage bees, Sinaloa beekeepers have adopted the new management practices recommended for managing Africanized bees, as follows:

Queen rearing is probably the key innovation. Mr. Sosa, Mr. Pompa, and the other beekeepers we visited now have queen-rearing operations, and stated that a beekeeper has to be a queen rearer. They estimate that it is necessary to rear about one new queen per year per hive managed. Queen rearing enables beekeepers to use colonies headed by a pure European queen mated to local drones. As a result, the worker bees, who are the offspring of the queen and her mates, are a mixture of pure European bees and hybrids. Because honeybee queens mate with 10 to 20 males, each colony probably contains a mixture of both types of workers Approximately two-thirds of the colonies headed by these queens are reasonably “gentle” (though not as gentle as most pure European colonies). One-third are manageable, but exhibit undesirable Africanized bee qualities — excessive defensiveness and excessive brood rearing at the expense of honey storage. These colonies can be identified during routine hive management and given a replacement queen that the beekeeper has reared.

Queens can be reared year-round in Sinaloa, because pollen- and nectar-bearing plants bloom year-round. Queens reared from the European breeder queens are marked with a spot of paint on the thorax. Then, when colonies replace their queens (which can give rise to genetically more Africanized colonies) the beekeeper can detect the loss of the marked queen.

Queen rearing requires some specialized equipment, special skills and time. While queens can be purchased from commercial breeders in Mexico, they cost enough ($4 to $5 each) that beekeepers find it economical to rear their own. In addition, rearing queens enables the beekeeper to be sure of quality. Breeder queens (i.e., pure European queens mated to all European drones) from which to rear virgin European queens for local mating are available from queen rearers in La Paz, Southern Baja California (a state that has not yet been Africanized); from a state-run breeding station on the Islas Marias, a group of islands about 70 miles from the coast; and from Hawaii. (Other U.S. sources are currently precluded because Varroa mites, a serious parasite of honeybees, are not yet found in Sinaloa. The mites are found throughout much of Mexico, and all of the United States except Hawaii.)

Social background

Adapting to Africanized bees in Mexico has not been confined exclusively to the beekeeping industry. The role of others besides beekeepers in adapting to Africanized bees has been important, as it continues to be in the United States. Numerous Mexican authorities and organizations (the department of agriculture, Red Cross, schools the fire brigade, police) cooperate to promote public awareness about the realities and dangers of Africanized bees, and to eliminate dangerously located colonies of feral bees within cities. In Mexico there have been no regulations quarantining the movement of bees in Africanized areas, as was done in Texas following the entry of these bees into the United States (but not in NM, AZ or CA) Mexican tort law is quite different from that in the United States and Mexican beekeepers and landowners where bees are kept are less concerned about financial losses from lawsuits than are their United States counterparts. As mentioned above, hives managed by beekeepers have not been responsible for any deaths in Sinaloa. Public awareness of this, and the above factors, have contributed to a climate in which beekeepers do not have much difficulty finding apiary sites. (Finding sites is difficult for California beekeepers because Africanized bees have raised the public's fear of bees in general.)

Management of pollination units

Beekeepers in Sinaloa have been able to provide pollination services sufficiently well that growers have felt little if any impact. In fact the beekeepers, SARH official and an extension agent with whom we spoke said that most growers are unaware that the bees currently pollinating their crops are any different from 5 years ago.

The success of the beekeepers in adapting has several angles. The most important is that beekeepers maintain less defensive bees in their hives by requeening with locally mated European queens. Also of importance is that colonies are moved into the fields and unloaded at night, typically after being loaded in the late afternoon or evening. This gives the hive time to calm down before daylight. If a colony is unloaded in the daytime, as was formerly common, the bees are more likely to abscond and be highly defensive. Even when moved at night, colonies remain more defensive than normal for a day or so after moving.

Pollination hives are set out in the crops in groups of about 10 (or as specified by the grower) along or close to farm roads going through or around the crop. This is similar to California practice. The hives are placed exactly as before Africanization, with no attempt to segregate people and hives. We observed groups of farmworkers working and eating lunch within 20 yards of hives and walking near them. Farmworkers told us that occasionally someone is stung, but they usually continue working, and that they know to avoid colonies recently moved into the field, because their bees are more likely to sting.

Large-scale stinging usually results from disturbing a colony's nest. There was a news report while we were there of someone on a tractor running over a nest of feral AHB in the ground, and being stung to death, but those are more fierce bees than the beekeepers keep; avoidance of such feral nests is the best prevention method.

Another factor that probably reduces the defensive behavior of the bees is the use of pollination hives with relatively low numbers of bees. Small colonies are well known to be less defensive than more populous ones, in both European and Africanized bees. The pollination hives in Sinaloa were comparable in number of bees to hives used in almond pollination in California. Hives used to pollinate almonds contain relatively few bees because almond bloom occurs in February, before colony populations have had time to expand following the winter. In contrast, the Sinaloa hives are kept small by beekeepers splitting the colonies or removing frames of brood, and, in agricultural fields, by a shortage of forage and the loss of foraging bees due to pesticides.

Hives used for pollination consist of a single jumbo hive body containing about seven frames, with no additional honey-storage boxes. This is a comb area equivalent to nine frames in a deep hive body commonly used in the United States. Bees cover most of these frames. (For almond pollination, most hives are rented in two-deep boxes, giving twice the comb area used in Sinaloa, but approximately the same number of bees.) Normally, a jumbo hive box holds nine or 10 frames (as it is used for the brood-rearing portion of a hive in large-colony honey production contexts, with additional boxes to contain honey placed above it). In the pollination hives there is a space when only seven frames are used, and cans for feeding syrup are placed in this space and filled as necessary to provide food for the bees.

The use of a single jumbo hive box as brood chamber is standard in northern Mexico, and predates the arrival of Africanized bees. The use of relatively small pollination units without honey supers also predates Africanized bees; these were originally used for the following reasons:

These relatively small pollination units have proven ideal in the post-Africanization period. About the only difference following Africanization is that growers are no longer willing to set the entrance screens to protect the hives from pesticide application. This would seldom be a problem in California where pesticides are applied more carefully with regard to the health of pollinating bee hives and beekeepers rarely close up their hives.

Cause for optimism

The arrival of Africanized bees in Sinaloa has affected predominantly the beekeepers, but has not had a great impact on commercial pollination. For the Sinaloan grower, there has been no rise in the rental tee nor shortage of pollination units available because beekeepers have been able to adapt their management practices. Beekeepers were able to divide hives and rear queens to make up for lost hives following Africanization. However, the numbers of colonies are still not up to pre-Africanization levels. From the perspective of the beekeepers, pollination contracts have probably helped them survive economically because honey production has diminished considerably following the arrival of Africanized bees.

How relevant are these Mexican experiences for California? We think that they are cause for some optimism. If Africanized bees should colonize much of California, (and climatic factors and competition from European bees may prevent them from doing so), the Sinaloa situation indicates that beekeepers will still be able to supply the necessary bees for crop pollination. In one key respect, California is better off than Sinaloa because queen rearing is already highly developed here, and California queen rearers have the capacity to rear large numbers of replacement queens if needed, including European queens mated to European drones. (The major queen-rearing areas are in the Sacramento Valley, which will not be reached by Africanized bees for some years, if at all.)

On the other hand, the total requirement of growers in California for hive rentals is about 50 times greater than in Sinaloa and cannot be met by in-state beekeepers alone. In particular, almond pollination will be greatly affected if regulations regarding Africanized bees limit the movement of bees between California and other states. Perhaps the biggest lesson from Sinaloa is that if beekeeping is profitable, and if beekeepers are allowed to continue their trade and are assisted in adapting to the new bees, then they will be able to supply the bees needed for pollination. Growers can support beekeepers, and themselves, by pushing for a rational reaction to Africanized bees, if they arrive in large numbers. This would involve a recognition that bees are necessary for pollination and that most of the public health problem of Africanized bees is not caused by managed colonies. (To an even greater extent than in Sinaloa, California beekeepers will maintain stocks in their colonies which are less defensive than the feral Africanized colonies.) It is also important that beekeepers are able to find locations for their apiaries and to transport bees from crop to crop, if beekeeping is to remain profitable and genetic dillution of the aggressive AHB is to continue.

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