Rosenbrand and Cooper note that
the program is still in the experimental
stage.
"We're still testing the concept
and doing research," says Cooper.
"Especially as we fine-tune release
rates, timing, the ability of these beneficials
to establish populations in vineyards,
and the optimal combinations of
insects to release."
Rosenbrand adds, "If this were
100% proven, Cooper would not be
working with us as a research scientist
to learn and explore the effectiveness
of using bio-control to control VMB."
Other research plots in California
In addition to working with
Spring Mountain Vineyard, in 2006
and 2007, the UC Berkeley team had
about 12 other research plots located
in Napa County, Sonoma Valley, the
Central Coast region, the Lodi area,
and raisin vineyards in the San
Joaquin Valley (these were directed
by Glenn Yokota, Cooper's counterpart
at the Kearney Agricultural
Center).
Cooper reports similar results from
around the state. "Crop damage was
minimal in all plots and both parasites
were recovered in monthly mealybug
samples."
Daane notes that a key is to first
suppress the mealybug densities with
properly applied insecticides. The sustainable
tools will not rapidly reduce
large, damaging mealybug populations,
but they have proven capable of
maintaining low density populations
below damaging levels.
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In 2008, Cooper will supervise eight
plots in the North Coast, eight in the
Central Coast, and eight in Lodi, but
those in Lodi will not use predators,
only parasites. Yokota will supervise
six plots in the San Joaquin Valley. The
researchers plan tomonitor each plot at
least once monthly.
The UC Berkeley team is also
investigating which natural enemies
might work best together. Cooper
explains that, in a Carneros vineyard,
they have isolated individual
vines in large, walk-in cages and
added different combinations of beneficial
insects (A. pseudococci,
C. perminutus, and C. montrouzieri).
The researchers hope to determine
how the species interact to control
VMB populations.
Any vineyard manager who has a
large mealybug infestation should
first knock it back with an insecticide,
notes Cooper. "The next step is to
then deploy bait to target Argentine
ants." As mentioned above, Argentine
ants disrupt the activity of beneficial
insects, so ant populations must
be controlled before biological control
can be successful. If someone
tries to release insects to control the
VMB, they won't do the job well if
there are large Argentine ant populations
which disrupt the beneficial insects.
"When we were working under the
Napa County compliance agreement,"
Rosenbrand recalls," before we began
the bio-control program, we sprayed
many times per year 
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with Dimethoate,
Lannate, Applaud, Provado, and
Lorsban. The attempt with all this was
VMB eradication!
"In 2006, we sprayed twice with
Applaud, and once in 2007. Applaud is
a soft chemical which is a growth regulator
and it does not allow nymphs to
become adults. The Applaud applications
were not intended for ant control
(and probably have little impact on the
ants)."
Stripping the bark from vines to
help to expose mealybugs is recommended
by Rosenbrand. "We stripped
bark manually in 2003, but have not
stripped since. Bark-stripping by hand
is incredibly expensive. There is a new
tool to air-blast the bark, which should
help decrease the cost of manual barkstripping.
"Someone who has a mealybug
problem can get a head start by controlling
antswith the use of ant bait stations,
and reducing VMB populations
through bark-stripping, and spraying
insecticides, to prepare the way for
beneficial insects."
All of these techniques are essential
to bring VMB populations from high
densities down to low to moderate
densities. At these lower densities, the
sustainable management tools described
here can then be employed to manage
VMB populations.
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