Distributed to:
USR:[MTS]INTERNET.DIS;20, mts
FILENAME: JULAPIS.94
Florida Extension Beekeeping Newsletter
Apis--Apicultural Information and Issues (ISSN 0889-3764)
Volume 12, Number 7, July 1994
AHB INVASION RUNS OUT OF STEAM?
Reports of African honey bee (AHB) colonization of western
Texas continue, but the movement appears to have slowed
significantly. And in neighboring New Mexico and Arizona,
confirmed finds may be from swarms moving across the Mexican
border, rather than migrating westward. The biggest question mark
concerns California which has yet to be officially invaded by this
insect, although there have been confirmed finds near the state
line.
In east Texas as well, the AHB has not advanced as far as
previous predictions indicated. The insect has yet to reach
Houston and it's now been over three years since the first colony
was found in the state. Has the invasion indeed run out of steam,
and if so, why? These questions as yet have no answers, but
already the press is writing about the phenomenon.
There are some intriguing reasons for the slowdown suggested
by Mr. Laurence Cutts, Florida's Chief Apiary Inspector, and others
examining the situation. The weather in the region has been
generally unfavorable (colder winters, later springs) for feral
bees. The bees may be approaching their climatic limits; the
present distribution when compared with that predicted by Dr. Orley
Taylor over a decade ago shows great correspondence. Texas is a
very large state; perhaps the AHB will take some time to reach
saturation in certain areas before the invasion can continue.
In addition, the AHB wave from Mexico has also met a challenge
that it didn't face in that country, the Varroa mite. Nor can the
potential ravages of chalkbrood, the foulbroods and tracheal mites
on wild populations be discounted. There is more than a little bit
of irony in the realization that the beekeeping industry's nemeses
might become allies in stemming the AHB tide.
Another suggestion is that the imported fire ant, well
entrenched in southern Texas, is responsible for predation on AHB
colonies. Nests in scrub are quite near the ground and migrating
swarms are small. There are reports that these ants are also
becoming more effective predators on managed European colonies in
Florida.
And what of the consequences of hybridization? Increased rate
of genetic crossing among AHBs, feral European bees and those
managed by Texas beekeepers could be responsible for restraining
the migration. The situation is quite different than in tropical
areas of Mexico and Central America. There, bees of European
origin had not formed large feral populations, providing limited
competition to the invaders, and over time, those in managed
colonies were almost completely replaced by AHB. Hybrids that
developed between European bees and AHB in the wild did not appear
to persist (See February and March 1992 APIS).
Unlike in more tropical areas, a population of feral European
bees already exists in Texas. This means greater competition for
the AHB in the wild. It will also be a continuing source of
genetic material above and beyond managed colonies to produce
hybrids. And the resultant hybrid population might persist longer
in these temperate regions than was the case further south.
However, they could still be at some disadvantage. Hybrids may not
be so migratory, one of the reasons suggested for AHB resistance to
mites and pathogens. This fact, along with addition of European
genetic material, could make them more vulnerable to a host of
problems than are AHBs.
In the end, no single cause is probably responsible for
checking the bees' advance. However, all of the above reasons
taken together could make a formidable barrier keeping AHB
populations at bay.
TRACKING HONEY BEE ANCESTRY
Even a cursory review of the apicultural literature reveals
that over hundreds of years honey bees have been imported from all
over the world. The results of this activity have been variable.
Among the successes would be introduction of the Italian bee (Apis
mellifera ligustica) which materially improved commercial bee
stocks, and is in general use today throughout the country. A
notable failure was the Cyprian bee (Apis mellifera cypria),
considered too defensive by most beekeepers. It has almost been
eliminated from the U.S. gene pool. In 1922, legislation to
control importation effectively reduced genetic immigration.
However, legal and illegal introductions have continued.
Considering the sheer number of importations, the question
arises concerning the eventual fate of these bees in the U.S. Dr.
Eric Mussen posed this question in his latest newsletter, From the
UC Apiaries, while reporting on a study by N.M. Schiff and W.S.
Sheppard in the Journal Experientia, Vol. 49, pp. 530-532, 1993.
The study's authors did not address Dr. Mussen's specific question.
Their purpose was to look at the genetic variation of feral
populations in the southern U.S. and find out if the AHB invasion
could be adequately monitored using existing European genetic
markers. They did this by analyzing mitochondrial DNA (mtDNA).
There are two primary sources of DNA in multicellular animals.
The one most heard about, often touted by the press as the best
crime fighting tool since the fingerprint, is from the nucleus of
the cell. This DNA is the chemical information that determines the
form of the organism and much of its behavior. It is inherited
from both the mother and the father and can effectively be used to
make unique identifications.
But there is another kind of DNA. It is found in small
energy-producing capsules outside the nucleus of the cell. These
organelles are called mitochondria (the singular is mitochondrion).
In multicellular animals, DNA associated with the mitochondria is
only inherited from the mother. This provides the means to track
maternal ancestry . All bees in a colony have the same mtDNA,
inherited from one single individual, their queen. Pioneering
studies on mtDNA by Drs. Glenn Hall at the University of Florida
and Deborah Smith, University of Kansas, provide evidence that
feral swarms of African maternal lines were primarily responsible
for AHB migration in the tropics. Study of human mtDNA also gives
rise to the provocative idea that all humanity descended from a
single Eve.
The Experientia study looked at 422 feral bee colonies sampled
from areas not undergoing AHB invasion. The bees came from nine
states (Florida was not included). Collection was restricted to
wild colonies, including those relocated, but not requeened by
beekeepers. The results are as follows:
State Mitochondrial Types Total
African Mel/Ibr Car/Lig
AL 1 14 24 39
GA - 4 28 32
LA - 10 41 51
MS 2 14 31 47
NC - 3 27 30
NM - 7 54 61
OK - - 3 3
SC - 21 59 80
TX 1 19 59 79
Total(%) 4 (0.9) 92( 21.8) 326 (77.3) 422
Mel/Ibr refers to two European honey bee races (Apis mellifera
mellifera and Apis mellifera iberica). The former is the German or
dark bee, while the latter is the Iberian bee, native of the
Spanish peninsula. These are grouped together and considered
"western" races. The "eastern" races include A. mellifera carnica
(Carniolan bee) and A. mellifera ligustica (Italian bee),
designated above as Car/Lig; both are thought to make up the
majority of the present U.S. commercial honey bee stock. The
eastern and western groups have been separated on the basis of
mtDNA structure. The African mtDNA was from the Egyptian honey
bee, Apis mellifera lamarckii, not Apis mellifera scutellata,
considered to be the ancestor of the AHB.
When analyzing the results of this study, it is important to
understand that the percentages noted above are only of mtDNA types
found in wild U.S. honey bees. They do not necessarily translate
into bee types. For example, even though four colonies were found
with African mtDNA, the authors identified the individual bees as
"European" using morphometrics. Thus, no bees determined to be
"Africanized" are present in the above samples. This is
problematic. Presence of lamarckii mtDNA is a certain indication
of African ancestry.
Is it reasonable to correlate percentages of a certain mtDNA
type to a specific population? One school of thought says no,
because mtDNA really may have no effect on a bee's structure or
behavior which are considered superior measures of identification.
However, different mtDNAs may result in different capabilities.
Enzymes coded by mtDNA are responsible for energy production in the
cell and must interact with those coded by nuclear DNA. These
functions may contribute to the differences in metabolic capacities
of African, European and hybrid honey bees discovered by Drs. Glenn
Hall at the University of Florida and Jon Harrison, Arizona State
University (see APIS June, 1993). In addition, because mtDNA is
inherited as a total package from the mother, its presence means
that it came from an unbroken maternal lineage. In the case of the
lamarckii mtDNA identified in the Experientia study, the time line
could reach as far back as the 1860s.
It is tempting, therefore, to make a correlation of mtDNA
types with bee populations. Dr. Mussen surrendered to this in his
article, concluding: "It will be interesting to see if the 22% of
feral bees with 'non-commercial' lineage can survive the
competition of AHBs for their feral territory."
STATUS OF U.S. BEEKEEPING
F.L. Hoff and L.S. Willett have just released their study
entitled The U.S. Beekeeping Industry. It is Agricultural Economic
Report Number 680, published by the USDA Economic Research Service,
69pp, May 1994. This document is required reading for anyone
interested in the changes taking place in the apicultural industry.
The introduction states in part: "This report updates
information on honey production, pollination and the relationship
of the U.S. beekeeping industry to agriculture and the environment.
The study was mandated in the Committee report that accompanied the
Agriculture, Rural Development, and Related Agencies Appropriation
Act of 1987. The mandate resulted from concern by beekeepers and
members of Congress about problems, issues, and challenges that
emerged during the 1980's with the potential to significantly alter
the beekeeping industry. These concerns included northward
migration of the Africanized honeybee, infestations of colonies by
tracheal and Varroa mites, the widespread use of highly toxic
pesticides, increasing honey imports, and efforts to discontinue
the honey price support program."
This report is an extremely valuable lobbying document. The
authors should be congratulated for providing the industry with
these facts and figures. The beekeeping community now has plenty
of ammunition to back up its arguments for public support in many
arenas. However, the time and expense to produce this document
will go for naught, if those in the beekeeping industry do not
actively use the information to its fullest potential. To obtain
a copy call toll free 800/999-6779 in U.S. and Canada (other areas
703/834-0125) and ask for AER-680. The cost is $12.00 payable by
Visa or MasterCard. To order a copy by first-class mail, send a
check for $12.00 ($15.00 for Canada or elsewhere) made payable to
ERS-NASS, 341 Victory Drive, Herndon, VA 22070.
NOSEMA CONTROL
Mr. Glen Stanley, Retired Iowa Apiary Inspector, provided some
advice in a recent letter to the American Bee Journal. It was
simple. If one controls nosema this helps the bees overcome other
obstacles like tracheal mites. In other words, asks Mr. Stanley,
"...why not begin fighting the battle where it would do the most
good by getting bees cleared of nosema first." Another basis of
good beekeeping, he says, is to remove all old, black combs (his
emphasis), the source of bacteria, fungal spores and other
materials the bees might unintentionally collect. Mr. Stanley's
message must continually be kept in mind by beekeepers interested
in getting the most from their colonies. Adhere to the
fundamentals of beekeeping and the bees will take care of the rest.
Sincerely,
Malcolm T. Sanford
Bldg 970, Box 110620
University of Florida
Gainesville, FL 32611-0620
Phone (904) 392-1801, Ext. 143
FAX: 904-392-0190
BITNET Address: MTS@IFASGNV
INTERNET Address: [log in to unmask]
|
