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Honey Bees Mite
Breathe Easier:
Mite-resistance testing service to be offered soon.
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Scanning electron micrograph of an
Acarapis woodi tracheal mite.
(K5069-24)
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Pollinating crops keeps honey bees
busy. But some bees are more vulnerable than others when it comes to getting
"winded" because of tiny tracheal mites that clog their airways.
Now, plans are in the works to create a new service that breeders can use to
check their bees' mettle against the parasitic mite, Acarapis woodi.
Scientists behind the plan expect it to speed efforts to pinpoint tracheal
mite-resistance traits worth breeding into the entire U.S. honey bee
population, whose crop-pollinating duties are a $15-billion asset to the
nation's agriculture.
Under the plan, Agricultural Research
Service entomologists in Baton Rouge, Louisiana, are providing a
Shelbyville, Tennessee, beekeeper with the scientific expertise necessary to
conduct mite-resistance testing as a commercial service.
Through such a service, for example, a client could decide to cull a
susceptible queen breeder colony or further propagate one that fares well
against the mites. A similar service operated in Ontario, Canada, helped the
industry there reduce the mite-to-bee ratio from 13 mites per bee to 1.5. |
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Microscopic view of a bee trachea
infested with tracheal mites.
(K5069-23)
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"We believe the most effective way to enhance resistance is to make
certain that breeding colonies can be tested for resistance and encourage U.S.
breeders to test their colonies," says Robert G. Danka, an entomologist
with ARS' Honey Bee Breeding, Genetics and Physiology Laboratory, in Baton
Rouge.
There, he and ARS colleague entomologist José D. Villa have used a
protocol for testing and characterizing the relative resistance levels of bee
stocks subjected to heavy mite infestations. Through such research, for
example, they've discovered one resistant honey bee strain that fends off the
mites through a behavioral trait called autogrooming. Simply put, this refers
to the bees' use of their legs to comb crawling tracheal mites out of the hairs
on their bodies. In trials, susceptible bees used as checks weren't so limber
and averaged more mites than resistant bees had.
In the May 2000 issue of the American Bee Journal, the two researchers
published results of a survey in which they characterized mite-resistance
levels in 83 breeder colonies managed by 8 commercial queen producers in
California, Hawaii, Louisiana, Texas, and Virginia. Specifically, they tested
young worker bees from the breeder colonies and compared them to bees from
colonies known to be resistant or susceptible. Of the surveyed colonies,
two-thirds proved resistant, while one-fourth were clearly very susceptible.
"It's remarkable how variable resistance is in the breeding pool,"
says Danka.
Eager to transfer what they learned to the U.S. bee industry, the researchers
raised the idea for a commercial testing service at a bee breeders' conference
held in January 2000 in Fort Worth, Texas. Backwood Apiaries owner Edwin R.
Holcombe attended that meeting.
"I was listening and decided to participate," says Holcombe, who has
been a commercial queen bee breeder since 1973, and owns 80 hives. Tracheal
mites "are still a serious problem to beekeeping," he adds,
"though the Varroa mite has been getting the attention."
In April, Holcombe spent a week at the ARS scientists' Baton Rouge laboratory
to learn their mite-testing protocol firsthand. It includes managing colonies
of resistant and susceptible bee stock for use as reference points, maintaining
"inoculation colonies" that are infested with mites, and tending
combs with developing young bees in incubators. Young adult bees that emerge
from the combs are carefully marked and placed in the mite-infested colonies.
After a week, the test bees are retrieved, dissected, and checked under a
microscope for mites.
Once Holcombe feels he's honed these skills, Danka and Villa will put them to
the test before certifying Holcombe's proficiency—and for good reason: The
testing service envisioned calls for handling at least 15 colonies from as many
as 10 queen-breeder clientele, on a first-come, first-served basis.
"I plan one more practice run," says Holcombe, who is eyeing a summer
2001 debut. Then it'll be time to get down to beesness.—By
Jan Suszkiw,
Agricultural Research Service Information Staff.
This research is part of Crop Production, Product Value, and Safety, an ARS
National Program (#305) described on the World Wide Web at
http://www.nps.ars.usda.gov.
Robert G. Danka and
José D. Villa are with the
USDA-ARS Honey
Bee Breeding, Genetics and Physiology Laboratory, 1157 Ben Hur Road, Baton
Rouge, LA 70820; phone (225) 767-9294, fax (225) 766-9212. |
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"Honey Bees Mite Breathe Easier "
was published in the March 2001 issue
of Agricultural Research magazine.
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