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["Lon J. Rombough" <lonrom@hevanet.com>]

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From: "ARS News Service" <NewsService@ars.usda.gov>
Reply-To: ARS News Service <NewsService@ars.usda.gov>
Date: Wed, 7 Jan 2004 09:01:28 -0500
To: "ARS News subscriber" <>
Subject: Wasps, Roses Team Up Against Bad Bugs

STORY LEAD:
Rose Gardens: A Thorny Problem for Pesky Caterpillars
___________________________________________

ARS News Service
Agricultural Research Service, USDA
Jan Suszkiw, (301) 504-1630, jsuszkiw@ars.usda.gov
January 7, 2004
___________________________________________

Agricultural Research Service scientists and cooperators are plotting a
war of the roses against apple leafrollers that plague fruit orchards.
 
Roses--the wild, multifloral kind--are the centerpiece of small gardens
that ARS and Washington State University (WSU) scientists are planting
around orchards to bolster spring populations of the parasitic wasp,
Colypoclypeus florus.

After mating, a female C. florus wasp crawls inside the cocoon that
envelops the apple leafroller's caterpillar stage and deposits about 20
eggs. Several days later, her maggot-like brood emerge to suck fluids from
the caterpillar, killing it. During the spring, the scientists observed,
only a small percentage of an orchard's apple leafroller population is
affected by such attacks. But during the summer, C. florus can thin the
pest's ranks by more than 50 percent.

Since 1999, ARS entomologists Tom Unruh and Robert Pfannenstiel and WSU
colleague Jay Brunner have sought to overcome the wasp's springtime lag
using "habitat modification." The approach involves planting gardens of
wild rose and strawberry as a refuge for a secondary host of C. florus
called the strawberry leafroller. This doesn't introduce a new caterpillar
threat to orchards, but rather provides the wasp's brood with a host of a
suitable size that's critical to their winter survival.

The result is a bumper crop of new wasps emerging in the spring to mate,
migrate into orchards and attack their primary hosts, Pandemis pyrusana
and the oblique-banded leafroller. Both are pests of apples, pears and
cherries.

In heavily infested areas, apple growers may spray orchards with
insecticide two to four times a season to keep these caterpillar pests
from damaging fruit. But making the orchards more hospitable to the wasps
in the spring could diminish the need for spraying, according to Unruh, at
the ARS Tree Fruit and Vegetable Insects Research Unit, Wapato, Wash.

A longer article about the gardens, now being field-tested in Washington
and Oregon, appears in the January issue of Agricultural Research
magazine, available online at:
http://www.ars.usda.gov/is/AR/archive/jan04/rose0104.htm

ARS is the U.S. Department of Agriculture's chief scientific research
agency.
___________________________________________

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