Photographer:Todd M. Gilligan and Marc E. Epstein Affiliation: USDA APHIS ITP Source:www.bugwood.org Copyright:CC BY-NC 3.0
The adult moth is approximately 0.3 inch long, with a wingspan of 0.4 - 0.5 inch, with the female being slightly larger. Both males and females have mosaic-patterned wings that are very similar to one another. The first pair of wings (forewings) is tan-cream in color, mottled with gray-blue, brown, and black blotches. The second pair of wings is gray with a fringed border. The wings are held in a bell shape over the abdomen when at rest.
Host Plant: Grape and spurge laurel are preferred hosts; but Lobesia botrana is also found on the fruits/flowers of blackberry, gooseberry, black and red currant, olive, cherry, prune, persimmon, kiwi, pomegranate, ivy, plum, privet, nectarine and carnation hosts.
Lobesia botrana attacks grapevines in several ways: the first generation larvae attack the flower clusters, second-generation larvae (July-August) feed on green berries in which they penetrate the berry and hollow them out, leaving the skin and seeds and third-generation larvae (August-September) cause the greatest damage by webbing and feeding inside berries and within bunches, which become contaminated with frass excrement. Additionally, feeding damage to berries exposes them to infection by Botrytis and other secondary fungi. With Lobesia botrana able to strike all the host plants mentioned above, if it were able to spread outside of California the economic damages would be easliy in the 100 millions.
European grapevine moth has two generations in its life cycle in northern Europe, three generations in southern Europe, and it is reported to have a partial fourth generation in warmer regions of Spain, Greece, Jordan, and Egypt. The first-generation population tends to be the largest, where the majority of females mate only once. Egg laying begins one or two days after mating. Eggs of the first generation are glued singly on flat surfaces on or near the flower cluster. A female can lay as many as 35 eggs/day for about 6 days; averaging 80-140 eggs/female depending on the generation. Egg hatch depends on temperature, and ranges from 3 to 5 days under optimal conditions in summer to 10 to 11 days in less favorable spring conditions. Also depending on climate the adult lifespan is from 1 to 3 weeks. The larvae of the first generation create webs around flower parts weaving them together and also feed on individual flowers and pedicels; they may enter the peduncle and cause the whole grape bunch to dry up. Like other larvae in the family tortricidae, when disturbed they will wiggle and drop down on a silken thread. Larval development is completed in 20 to 30 days depending on temperature. Pupation occurs inside a webbed cocoon that may be found on the flower cluster, under the bark on cordons, or in soil cracks. Adults emerge 6 to 14 days after pupation. Studies in Europe have shown that the adult and egg stages are considered the most vulnerable to environmental factors.
Surveys for Lobesia botrana started in 1986 and there weren’t any confirmed populations until 2009. Survey activities have determined this insect is present in several counties within the central portion of California and the state had to quarantine 162 square miles of land back in 2010. In January 2013, the quarantine was lifted for 4 California counties: Santa Clara, Nevada, Santa Cruz and a portion of Sonoma County; releasing 317,000 acres from quarantine.
U.S. Habitat: Wherever vineyards are present; first found in Napa Valley in California.
U.S. Present: CA
Red delta traps with Lobesia botrana pheromone lures can be placed two weeks before grape bud break, with 2 traps/vineyard and a minimum of 1 trap for every 30 acres. These traps can be used to detect the first, second and third generation emergence of the Grapevine moth adults.
In countries where Lobesia botrana is established, control measures are targeted at the second generation. However, treatment of the first generation is recommended if populations are high or if treatments are conducted on an area-wide basis. Under California conditions, control of both first and second generations may be warranted, given that this is a newly introduced pest. Insecticides are less effective on the third generation because they are within the grape bunches.
Several reduced-risk insecticides are registered for use in grapes to the larvae. For several years, mating disruption has been studied in Europe; and has shown to be most effective when grapevine moth populations are low and when applied to large areas of over 10 acres. Biocontrol Isomate-EGVM is registered for Lobesia botrana pheromone mating disruption.
In the European literature there have been hundreds of predators and parastioids discovered. The parasites that are reported to cause the greatest impact are those attacking the overwintering pupa. In Spain these include the parasitic pteromalid wasps Dibrachys affinis and D. cavus, which are reported to cause up to 70% pupal mortality, whereas in Italy the ichneumonid wasps Dicaelotus inflexus and Campoplex capitator are the most important. There is still much to be known about the California populations. On the other hand, the European studies show good “starting points” for controlling the Grapevine moth in California so it doesn’t spread to other states that have a growing number of vineyards and other fruit orchards, like Texas.
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Varela, L. G., Smith, R. J., Cooper, M. L., & Hoenisch, R. W. 2010. European grapevine moth, Lobesia botrana. Napa Valley vineyards. Practical Winery & Vineyard. March/April, 1-5.