FILENAME: FEBAPIS.90
Apis--Apicultural Information and Issues
Florida Extension Beekeeping Newsletter
Volume 8, Number 2, February 1990
AFRICAN HONEY BEE RESEARCH IN FLORIDA
Last month I reported on efforts to develop an African bee plan in Florida. A
large part of the projected effort will be basic research on the insect. The
head of IFAS' African bee research program, Dr. Glenn Hall, and his associates
continue to be busy generating information that will affect how we will deal
with the invasion of the African honey bee.
Research at the University of Florida focuses on honey bee deoxyribonucleic
acid (DNA). DNA provides the basic blueprint for how a honey bee is
constructed and behaves. DNA in the nucleus of bee cells comes from both
parents at the time the egg from the queen and sperm from the drone unite.
However, DNA is also found in other parts of the cell, including the energy
producing capsules, called mitochondria. Because DNA from mitochondria comes
only from the egg, it is inherited strictly from the queen. It is
important to keep in mind the origin of specific kinds of DNA (nuclear vs
mitochondrial) to fully understand and appreciate Dr. Hall's work.
The significance of Dr. Hall's research was shown by a major article published
in the May, 1989 issue of "Nature," one of the most widely read scientific
journals. The review process leading to publication in "Nature" is strict and
very few papers pass the rigors of the editors. A measure of the journal's
prestige is that the discovery of DNA itself, resulting in the awarding of the
Nobel Prize, was first published in its pages. The results of Dr. Hall's
paper were corroborated by another authored by Deborah Smith in the same
issue.
Dr. Hall's paper 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." The companion paper authored by Smith
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." He called for more study based on both
nuclear and mitochondrial DNA to provide further information on the
Africanization process.
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 queens 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 asymmetrical 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.
Recently, however, Dr. Eric Mussen in "From the U.C. Apiaries, " quoted the
editor of the Oregon Beekeepers' Association's Newsletter, "The Bee Line," who
conducted an interview with Dr. Thomas Rinderer, USDA Research Leader on
Africanized bees. In that article, the small sample size in the Smith paper
was criticized. However, it was reported incorrectly as 10 bees (not hives)
in Brazil and 17 or 18 bees (not swarms) in Mexico, when the correct figure
was 10 hives in Brazil; 12 hives from Venezuela and 39 feral swarms in Mexico.
In total, the number of both wild and managed colonies examined by
investigators reported in the two articles above was 87, after subtracting out
three colonies sampled in common. Dr. Rinderer was also quoted as saying that
no one has looked at the parental origin of DNA, perhaps another oversight by
the editor.
The first evidence for nuclear DNA differences between African and European
honey bees was published by Dr. Hall in the Proceedings of the National
Academy of Sciences in July 1986. This pioneering study sparked similar
interest in other research laboratories around the country. Since then, Dr.
Hall has given talks on the subject at state and national bee meetings, as
well as the 1988 American Bee Research Conference. In the same year, he
authored a full chapter describing honey bee nuclear DNA and will soon have
published a major article in the journal, "Genetics," on the same subject.
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." Not only nuclear DNA evidence, but
practical observation corroborates this view which is the least controversial
of those mentioned here.
4. Swarms of "Africanized" European mother lines have not been found in
the migrating feral population, but it is expected that some will be caught
near European apiaries. Evidence for this comes from both nuclear DNA and
mitochondrial DNA studies.
5. The above interpretations are so far only valid in tropical climates. In
the temperate U.S. and places like Argentina, zones with significant
hybridization between African and European bees are likely to occur. This
prediction was published by O. Taylor and M. Spivak in 1984. Recent studies
by Brazilians show that a hybrid zone already exists in temperate Argentina.
Therefore, as Dr. Hall pointed out in his report on DNA research funded
partially by the Florida State Beekeepers Association in a recent 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 Univ. 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."
As mentioned in last month's newsletter, as part of the Florida African Bee
Plan, Dr. Hall is asking for research funding to study methods of stock
identification and certification using nuclear and mitochondrial DNA. A
current project focuses on controlled matings in Africanized areas. He will
also be establishing baseline information and studying the African bee's
dispersal patterns in Florida.
FLORIDA AGRIBUSINESS COMPUTER SHORT COURSE
The 1990 Florida Agribusiness Computer Short Course is scheduled for March 19-
22 at St. Petersburg Junior College in Clearwater, FL. Billed as helping
agriculturalists by "tooling up for the '90s," the event promises a great deal
for everybody. "In the early years, we just wanted growers to be aware of
computers as a new tool," says IFAS Extension Assistant Dean Jim App, "Now
people want more in-depth training...So we're offering hands-on courses
growers can use to make budgets or keep records...These things people have to
do whether they have computers or not. The computer is just a tool that can
help."
Special sessions on beginning and advanced spreadsheet budgeting, taking
command of the computer's disk operating system (DOS), wading through word
processing and managing information using data base programs are all featured.
Many sessions are expected to fill up fast so advance registration is
recommended. Each session has been expanded to a full half day and costs $30
until March 5; $40 thereafter. Special airline fares and room rates have
been arranged. For a registration form and more information, contact Computer
Short Course, 551 IFAS, University of Florida, Gainesville, FL 32611-0551, ph
904/392-5930.
PESTICIDE PARADOX
Many are increasingly disturbed at the amount of pesticide being placed in the
honey bee's environment to reduce Varroa mite populations. In response to
this, regulators in Florida are under the gun to reduce movement restrictions.
Current rules require all colonies in a yard to be treated before being moved,
if a single mite in a roll jar is found by an inspector. Given that the
economic threshold is not known and the fact that treatment at best will not
kill 100% of the mites present, it seems reasonable to suggest that this is
not realistic and many have called for deregulation within the state.
Unfortunately, according to Dr. Harvey Cromroy, IFAS Acarologist in charge of
Varroa research, this presents a paradox. Because the only currently legal
treatment using APISTAN (R) has a Section 18 emergency label, deregulation
would by fiat cancel the registration. Therefore, no one would be allowed to
use the product, clearly an unacceptable alternative.
THE BEE BREEDER
Many authorities acknowledge the key to better beekeeping in the future will
be much more emphasis on breeding bees. "The Bee Breeder," is a new
publication designed to keep beekeepers informed on latest research
developments and provide practical approaches to bee breeding. The premier
issue includes articles on California African bee research, Brazilian
beekeeping, stock importation and comb cell size. "The Bee Breeder" has a
decidedly California slant and is published with support of the California Bee
Breeders Association. It will be published three times a year and
subscriptions are available for $5.00. Send subscriptions to 6745 Bucktown
Lane, Vacaville, CA 95688.
Sincerely,
Malcolm T. Sanford
0312 IFAS
202 Newell Hall
University of Florida
Gainesville, FL 32611-0312
Phone (904) 392-1801
BITNET Address: MTS@IFASGNV
INTERNET Address: [log in to unmask]
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