European grapevine moth pupa inside
partially open cocoon found under the
bark. Photo Jack Kelley Clark, courtesy of
UC Statewide IPM Program.
Ground surveys for immature
insects by vineyard, regulatory, and
UC Cooperative Extension personnel
were more fruitful. Almost 30 individual
properties inNapa County are now
presumed positive for at least one life
stage of L. botrana. By November 2009,
trapping efforts had ended for the season,
concurrent with the lack of a population
in the adult stage.
In late winter/early spring 2010,
trapping efforts will resume in Napa
County, and expand throughout California
to determine statewide distribution
of L. botrana. Considering its status
as one of the most damaging pests of
grape berries in the Mediterranean
region, and its recent rapid spread in
Chile, this state-wide monitoring effort
will be critical to delimit populations
to track the pest’s spread and damage
in California vineyards.
Currently, the European grapevine
moth has been classified as a Q-rated
pest by the CDFA, a temporary rating
pending determination of a permanent
rating. Once adequate information has
been collected on its statewide distribution,
L. botrana will then be assigned an
A, B, or C rating.
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Pests with an A-rating are organisms
of recognized economic importance that
are subject to state-enforced action
involving eradication, quarantine regulation,
containment, or rejection; B-rated
pests generally have established, but not
widespread populations, are recognized
as economically damaging, and are subject
to regulatory action at the discretion
of the Agricultural Commissioner at the
local level. C-rated pests are recognized
as generally distributed, and are therefore
not subject to regulatory action
except to retard spread, and at the nursery
level to assure pest-free plants.
During the 2009 harvest, quarantine
zones and compliance agreements
established for the light brown apple
moth (Epiphyas postvittana) in Napa
County may have limited the movement
of European grapevine moth.
Geographic distribution
L. botrana was first described by
biologists Denis and Schiffermüller in
1775 in Vienna, from samples collected
in Italy, and was classified as a pest in
Austria in 1800. It was reported from
several European countries and Russia
in the 1800s and has since spread to
North and West Africa and the Middle
East. It was introduced into Japan
before 1974 and recently into Chile.
Climates in the area occupied by the
pest can be characterized generally as
dry or temperate. The currently
reported global distribution of L.
botrana suggests that the pest may be
most closely associated with habitats
classified as montane scrub, Mediterranean
scrub, and temperate broadleaf
and mixed forest.
The Chilean department of agriculture,
Servicio Agrícola y Ganadero
(SAG), issued the first report on L.
botrana in the Americas on April 23,
2008. Surveys conducted in 2008 and
2009 showinfestations in all grapegrowing
regions of Chile, a spread of approximately
1,500 kilometers (930 miles).
Hosts
European grapevine (Vitis vinifera),
American bunch grape (V. labrusca), and
spurge laurel (Daphne gnidium), a common
shrub inMediterranean Europe, are
the main hosts. Some researchers theorize
that D. gnidium constitutes the original
host of L. botrana and its adaptation to
grapes is a relatively recent event.
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The larva feeds on all cultivated
grape varieties, although they develop
better on some than on others. Females
lay eggs almost exclusively on flower
clusters and berries.
The literature includes about 25
hosts other than grape, however
Lobesia is found only very rarely or
accidentally on other hosts with the
exception of D. gnidium. Vitis vinifera
constitutes the main food resource.
L. botrana is considered a major pest
only on grapevines. In olive, only the
flowers are infested, never the fruit;
therefore, olive trees next to vineyards
may constitute an important source of
infestation of nearby vines by moths in
the late spring.
Females select plants to lay eggs on
by flying upwind following olfactory
cues.Once they land on a plant they also
taste the surface with contact chemoreceptors
before laying their eggs. Plant
surface chemicals stimulate or deter egg
laying. The host-plant range in
California will need to be studied to
establish the role that alternate hosts
play in the life cycle of L. botrana.
Identification
The adult moth is approximately ¼
inch long. Female moths tend to be
slightly larger, although both sexes
have mosaic-patterned wings. The first
pair of wings is tan-cream and mottled
with gray-blue, brown, and black
blotches. The second pair of wings is
gray with a fringed border.
Unlike other common vineyard tortricids,
which lay eggs in overlapping
masses, L. botrana lays single, elliptical,
and flat eggs (0.03 inches in diameter).
As it ages, the iridescent, creamy white
egg turns yellow, and later blackens as
the head of the developing larva
forms. The larva hatches from the edge
of the egg, leaving the translucent egg
shell attached to the plant.
Both sexes have five larval instars;
fully grown larvae are approximately
½ inch long with dark thoracic legs.
First-instar larvae are creamy white
with a black head. Older larvae have
lighter, yellowish-brown heads with a
dark border at the rear edge (closest to
the body) of the prothoracic shield
(segment behind the head; see photo).
Young larvae have tan bodies, whereas
older larvae take on the color of their
gut contents and food source (from
dark green to shades of maroon).
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