A pesticide used to kill varroa
mites in Georgia bee hives is also proving effective in killing
small hive beetles.
Varroa mites and small hive
beetles
are major pests to bees and their keepers in Georgia. In late
January, Georgia Commissioner of Agriculture Tommy Irvin granted
a temporary clearance for beekeepers to use coumaphos, a
pesticide,
to fight them. However, beekeepers must remove honey from the
combs of coumaphos-treated hives.
Important for
Growing
Crops
“Varroa mites and small hive
beetles are causing our honey bee population to dwindle,”
Irvin said. “Honeybees play an important role in pollinating
many fruits and vegetables and are responsible for pollinating
plants that account for approximately one-third of the food we
eat.”
The small hive beetle is a new
pest, but varroa mites have been around for years.
“We’ve been fighting varroa
mites since 1987,” said Keith Delaplane, an Extension
Service
entomologist with the University of Georgia College of
Agricultural
and Environmental Sciences. “The recent problem is their
resistance to the old stand-by product we were
using.”
Delaplane said the new pesticide
is being used for two reasons. “One is because the varroa
mites have become resistant to the current pesticide,
apistan,”
he said. “The other is to fight a new pest, the small hive
beetle.”
Came to the U.S.
in 1998
The small hive beetle was
unknown
in the United States until its unexpected arrival in 1998.
“That
year,” Delaplane said, “we found it in Georgia and in
Florida.”
Both pests are harmful to bees
and to beekeepers’ wallets.
“The varroa mite is like
a tick,” Delaplane said. “It attaches to the outside
of the bee and actually pierces into it. It’s broadly dispersed
across the state and is causing colonies to die all over
Georgia.”
The small hive beetle, on the
other hand, is much less widely distributed, with concentrations
in south Georgia and several counties in metro
Atlanta.
“It’s a hive
scavenger,”
Delaplane said. “The larvae are carnivorous and eat immature
bees.”
Hurt the Bees and
Eat the Honey
They also eat honey. “They
go tunneling through the combs and make a mess of
everything,”
he said. “Colonies that are severely infested will abandon
the nests, and the beekeeper comes back to find an empty
box.”
Delaplane said the beetles can
linger in colonies for weeks before causing damage. “When
conditions are right, the larvae explode, and the colony comes
crashing down,” he said.
U.S.
Department of Agriculture scientists had been looking for
products
to control varroa mites, anticipating the day the current
control
product would stop working, he said.
A ‘Silver Bullet’
for Both Pests
“One of them, coumaphos,
looked promising,” Delaplane said. “When the small hive
beetle showed up, they decided to try coumaphos on them, too.
And it worked. So fortunately we got a silver bullet, so to
speak,
that works for both of our problems at once: the resistant mites
and the beetles.”
Georgia has 75,000 bee colonies
and 2,000 hobby and commercial beekeepers. The industry
generates
$70 million each year in the state through sales of honey,
beeswax,
queen bees and package bees.
“Georgia ranks 14th in the
nation in honey production and second, behind California, in
queen
bee and packaged bee production,” Delaplane said.
“These
are bees that are shipped all to beekeepers over the world for
starting up colonies and for crop pollination. We dominate on
the east coast as a supplier of bees.”
Searching for
Nonchemical
Controls
Delaplane is doing his part to
fight these pests. “My research focuses on alternative
controls
that are less chemically intense,” he said.
Last summer, he tested a hive
screen that controls the varroa mites. “The screen creates
a false floor in the bee hive,” he said. “When the
mites
fall through the screen, they have trouble climbing back onto
the bees.”
The screens were developed in
France. Georgia beekeepers are now using them.
