APIS Volume 14, Number 4, April 1996
In this issue
- Toward Honey Bee Domestication--The Varroa Connection
- The Africanized Honey Bee--A Risk To Human Health?
- Sex Determination--Whither the Y?
- How Many Drones?
TOWARD HONEY BEE DOMESTICATION--THE VARROA CONNECTION
1987 was a pivotal year in U.S. beekeeping. Introduction of the Varroa mite in October sent a shock wave through the beekeeping community that reverberates to this day (see October 1987 APISIt has meant changes in management practices, increases in operating expenses and losses of many honey bee colonies. Paradoxically, it has also ushered in renewed opportunities for beekeepers in the pollination area, as growers and others noticed reduced numbers of honey bee pollinators in the environment (see July 1995 APIS). So far, only anecdotal information and "guesstimates" have been made about the full impact of Varroa on unmanaged honey bee populations. Given the dynamics of the situation, we probably will never know the full story.
It is clear that a new kind of honey bee management is emerging from the parasitizing effects of the Varroa bee mite. Two kinds of beekeepers can now be identified; those with experience "before Varroa," and those who began apiculture "after Varroa." Persons in the latter category cannot appreciate the relative laissez-faire beekeeping possible in the past. This state of affairs is also being reflected in the bees themselves. No longer able to exist in large numbers in the wild, these insects are being pushed toward a greater reliance on humans that can only be called "domestication."
According to Dr. D.F. Morey, "Some time in the past 12,000 or so years, most of humankind began to experience a profound shift in life style. Stone Age hunters and gatherers of wild foodstuffs started to cultivate plants and raise animals for their own use." (The Early Evolution of the Domestic Dog, American Scientist:82, Jul-Aug, 1994, pp. 336-347). Given the role of animal and plant domestication in human welfare, Dr. Morey says, there is no surprise to find argument about what it really is, how it originated and why. There are two theories on the subject: 1) domestication was a rational decision by people to raise, cultivate and manipulate organisms, or 2) domestication was the consequence of evolutionary chang in physiology (processes) and morphology (structure) by organisms in response to a new ecological niche--association with humans.
Dr. Morey concludes that the former of the above questions is flawed because it focuses on the human role in the process. An evolutionary model, he says, is more scientific and would include not only morphological, but behavioral changes not necessarily the result of human action. The major problem, Dr. Morey concludes, is that we cannot get into an early human's brain to figure out what was being thought at the time.
The dog is likely the first domestic animal Dr. Morey says and provides some insight into how it indeed has changed to adapt to living with humans. A range of other animals along with their time of domestication is published in a chart accompanying Dr. Morey's article. Significantly, no insect appears. Two possible candidates would be the silk worm and honey bee. Most beekeepers know the history of the latter, a creature that historically resisted domestication at every turn and to which humans had to adapt. As far as we know, few changes occurred in either honey bee structure or behavior to accommodate to humans similar to those in the domestic dog. This is in spite of the fact that both organisms have been associated with humans for almost as long.
The coming of Varroa, however, may signal an end to this historic independence of honey bees from humans. Wild colonies are declining and managed ones need beekeepers far more than ever before to survive the devastating effects of the mite. And unlike with early humans domesticating the dog, we can determine intent. Beekeepers could simply let all colonies infested with Varroa go without treatment. It would take a great many years, but in the end a mite-resistant or -tolerant bee would emerge. Instead, humans keep honey bee colonies alive by chemical intervention because they are valuable to us for a number of reasons, a clear case of willful domestication.
THE AFRICANIZED HONEY BEE--A RISK TO HUMAN HEALTH?
The coming of the Africanized honey bee has prompted a review of the possible human health risks posed by this insect. Dr. M.J. Schumacher and N.B. Egen, Department of Pediatrics, University of Arizona College of Medicine, Tucson, AZ, published their findings on this important topic (ARCH INTERN MED: Vol. 155, pp. 2038-2043) in October 1995. The paper describes the effects of the venom, evaluation and treatment of multiple bee stings (toxic envenomation) and the recognition, management and prevention of allergic reactions to Africanized bee stings.
The last topic above also includes European honey bees, for the authors conclude there is little difference between the venoms of the races. Both have almost equal amounts of similar major components: melittin, phospholipase A2 (PLA2), hyaluronidase, apamin, histamine and mast cell degranulating peptide. This means that there is little difference between risk to humans posed by the venom of either Africanized or European bees.
The major difference between the two bee types, according to the authors, is the possibility of mass attack, shown to be more prevalent in Africanized honey bees. Many individual stings can result in poisonous (toxic) reactions to the venom that are not related to allergy. And such reactions (toxic envenomation) can occur from as few as 50 stings. Studies of specific incidents show that the dose of venom per body weight is extremely important in determining subsequent effects. Specific symptoms and treatment for toxic envenomation are described by the authors. Things can also get more complicated when both envenomation and allergic reactions occur together, according to the authors. It may not be easy to determine which is in fact occurring, and they recommend treating for both conditions if in doubt.
The article gives advice on prevention of both envenomation and anaphylaxis (allergic reaction). In particular the authors recommend education programs to alert the public about what to do in case of attack: outrun the bees and cover the mouth and nose prevent airway stings. They say only trained personnel should attempt to remove established bee nests in areas of Africanized bees, and people enjoying outdoor recreation should always be on the alert. Most at risk are workers who clear vegetation or cut tall weeds and grass with machinery.
Although massive stinging attacks by Africanized honey bees are now rare, this bee may spread to warmer areas, the authors concede. Treatment of severe toxic reactions to multiple stings should include management of shock and possible organ damage. And patients with trivial allergy could be more at risk from anaphylaxis because of multiple stings. Any physician treating bee stings could do well to have this article on hand for its relevant, complete and up-to-date information.
For more information on reactions to stings, see March 1991 APIS. Information on use of stings in apitherapy is found in the July 1993 and February 1994 APIS.
SEX DETERMINATION--WITHER THE Y?
The genetics of honey bees is complex and confusing. The queen honey bee, a single individual, is the source of all the eggs in a colony, half the genetic material of any individual worker bee and the full amount provided to every drone. In the worker's case, the other half of their genetic material is donated by the drone in the form of sperm; the queen mates with several drones (see following article). She stores their sperm in her body until it is needed. This system results in a colony of several related subfamilies with the same queen mother, but different fathers. Each subfamily may also have a different penchant for certain work in a colony. For example, there may be nectar foraging, pollen foraging and undertaking specialties in these groups, reminiscent of guilds or professions in human society.
The queen honey bee has the ability to choose whether or not to fertilize each egg she produces. All fertilized eggs become females in a colony; they are characterized by 16 pairs of chromosomes (32 total). This organization composed of chromosome pairs is called diploid. Drones are produced only from unfertilized eggs, a process called parthenogenesis. They are haploid, having only one-half the number of chromosomes (16 total) that have no complementary pairs. This honey bee genetic system, therefore is named as a combination of both conditions, haplodiploid . It results in interesting things such as half sisters, super sisters and on rare occasions, diploid drones. For social insects, haplodiploidy allows individuals to give up their lives through "altruistic" behavior with a minimum loss of their own genetic contribution. It also results in a supremely female society, a matriarchy of the first order where males a relegated to a relatively minor role. They not only become expendable during the mating act, but are the first members of the colony to be eliminated in the face of stressful environmental conditions.
The genetic system in humans is quite different. All eggs are fertilized, so all individuals are diploid. Sex determination is the result of combinations of two sex chromosomes, the X and Y. If an X and Y come together, a male results; two X's become a female. Pretty simple. And, as Kenneth Miller suggests in "Whither the Y" (Discover, February 1995, pp. 36-41), his Y chromosome has dominance in all cases, whether it be use of the male pronoun when gender is unknown or immediate access to jobs, promotions and raises in what some call "good-old-boy circles." In addition, the male surname is also the default bestowed on any female becoming married in most western human societies.
Male gender was a defining force in school, Mr. Miller says, where he learned that boys did indeed have something that girls lack, even in their genes. If a Y chromosome exists, for example, no matter how many X's there might be in humans, the male sex prevails, Mr. Miller says, ensuring human male supremacy. Here is his vision of fertilization: "I imagined the poor little passive X chromosome just waiting to see whether the lucky sperm...carried an X or a Y. In either case, the X had to wait for the male to show up and make the decision. The Y really is the boss." Although perhaps dominant, however, unlike a single X chromosome, the Y cannot go it alone. It requires an X for development to continue, Mr. Miller says, his ego somewhat deflated. That's because the X carries many genes required for muscle development, blood clotting and color vision. Unfortunately, Mr. Miller is forced to conclude, the human Y chromosome turns out to be a genetic wimp, carrying only 15 genes to the 1,500 to 5,000 found on the X.
The puny Y is a result of a Faustian bargain Mr. Miller says, quoting Dr. William Rice, University of California, Santa Cruz. Not only do the X and Y chromosomes become different over time (the Y loses genes as it becomes more "self-centered"), but the Y also loses its genetic repair mechanism in the bargain. Presence of the small Y limits protection from defective genes that may be found on the X, the reason color blindness, hemophilia, Duchennes muscular dystrophy and many other conditions occur mainly in men. The two more robust X chromosomes in females can often recombine with each other to fix errors that might occur due to mutations or other factors. The Y, however, has very few genes to compensate for (complement) mutations on the X and this all-important recombining ability is compromised. Thus, Mr. Miller says, "...the Y accumulates one mistake after another as it is passed from father to son...shrinking in function, until nearly all but the sex-determining gene has been discarded."
Mr. Miller concludes that this process could eliminate the Y chromsome altogether. The defining genetic feature of human maleness, therefore, might not be the presence of something, but lack of it--a chromsome. The result: a species where females are XX and males are XO. This has already happened in some fruit flies and fish. Mr. Miller mourns what he sees as the eventual loss of the Y chromosome and suggests that the male pronoun rule and other privileges are nothing more than logical compensation for the genetic weakenesses endured by men.
Taken to the extreme, could male humans end up like male fruit flies, as Mr. Miller fears? Or even worse, like honey bee drones? My sources say it's not likely. Although XO's are males, so are XY's, the normal situation in some fruit fly species. More significantly, only the sex chromosomes are involved, the rest of those in the body do not have the same dynamics. Drone honey bees are a different kettle of fish. They are effectively XO in the strictist sense for all genes. With only a single set of chromosomes, none have a complement, leaving all of them unprotected against deleterious genetic change on the X chromosome.
HOW MANY DRONES?
How do we know what we know? This question can plague the educator who is supposed to be on top of things. It stops us cold at times. We have said it for so long, it seems like second nature. Yet, often we don't really know its source. Take the following question, for example. How many drones mate with a queen during the brief time when she is receptive? I usually say 10 to 15, perhaps 17 when I'm expansive. Thanks to Steve Taber, retired from the U.S. Department of Agriculture for many years, but who continues to write in American Bee Journal, I now know where this information comes from.
In his recent article (April 1966, pp 261-2), Mr. Taber gives us the scoop, not in spades, but in marbles. For after all is said and done it becomes a statistical question. Mr. Taber put it this way to a statistician: "Given: a large container with black and white marbles, (the marbles represent marked and unmarked drones), which are well shaken up, you reach in with a scoop and withdraw some and record whether the marbles are either all black, all white or of both colors. At the end of several hundred of these samples the question is asked, 'What is the average number of marbles in each scoop sample?' Of course the 'scoop' represents the queen on a mating flight."
The results from Mr. Taber's data and investigations into the matter agree with those of some other studies. The conclusion is a happy one. It vindicates what we educators "knew" all along. Queens mate with about 10 drones on the average during their mating period.
Sincerely,
Malcolm T. Sanford
Bldg 970, Box 110620
University of Florida
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©1996 M.T. Sanford "All Rights Reserved
