Adult Recognition
Adult FWL: 6.0-7.5 mm
The forewing is yellow or yellowish orange with a well-defined dark-brown to black median fascia. Males and females exhibit no sexual dimorphism in wing pattern although females may be slightly larger than males. Males lack a forewing costal fold. Male genitalia are distinguished by a reduced uncus, short socii, prominent transtilla, distally triangular valva, and large aedeagus. Female genitalia are distinguished by a broad, short ductus burase and a corpus bursae with numerous sclerotizations and spines.
Adults may be confused with other species of Eupoecilia or European Cochylini, although E. ambiguella is the only cochylid commonly associated with grape. A genitalic dissection can be used to confirm E. ambiguella identity.
Larval Morphology
Late instar larvae are approximately 10-12 mm in length. The head, prothoracic shield, and legs are dark brown to black. Body color varies from brown to yellow and green. Pinacula are large, conspicuous, and brown. The anal shield is pale brown.
Larvae cause damage similar to Lobesia botrana and the two species can be found sympatrically. Other tortricid grape pests include: Argyrotaenia franciscana, Argyrotaenia ljungiana, Epiphyas postvittana, Paralobesia viteana, Platynota stultana, and Proeulia spp. Larvae of E. ambiguella can be separated from the larvae of other tortricid grape-feeding pests by the L-group (or prespiracular) pinaculum on T1, which extends horizonally beneath the spiracle in E. ambiguella.
Biology
The life cycle of E. ambiguella is similar to that of Lobesia botrana, with the exception of two generations for E. ambiguella versus three or more generations for L. botrana. Over most of its range, adults are present in May and June for the first generation and again in August and September for the second generation.
Females deposit eggs singly on buds, pedicels, and flowers during the first generation, and on grape berries during the second generation. Early instar larvae burrow into the buds or berries and feed internally; later instars web together buds or berries, and a single larva can feed on up to a dozen berries. Pupation occurs in leaves for the first generation and under bark for the second generation. Overwintering occurs as a second generation pupa. Development time is highly dependent on temperature and humidity. The optimum relative humidity level for development is 70% or higher; eggs will fail to hatch at low relative humidity levels.
Economic losses on grape are caused by direct feeding damage and secondary infections. Feeding damage is similar to that of Lobesia botrana. Larvae of the first generation cause minor damage by feeding on flower buds, while those of the second generation cause the most damage by feeding on grape berries. The most significant losses are due to secondary infection of feeding sites on berries and clusters by Botrytis cinerea. Economic thresholds vary with the type of grape and cultivar.
Host plants
Although grape (Vitis vinifera) is the most economically important host, E. ambiguella has been recorded from plants in several families.
| Family | Genus/species | Common name |
| Aceraceae | Acer campestre L. | hedge maple |
| Araliaceae | Eleutherococcus Maxim. | ginseng |
| Araliaceae | Hedera helix L. | English ivy |
| Araliaceae | Hedera L. | ivy |
| Caprifoliaceae | Lonicera L. | honeysuckle |
| Caprifoliaceae | Lonicera periclymenum L. | European honeysuckle |
| Caprifoliaceae | Lonicera ramosissima Franch. & Sav. ex Maxim. | |
| Caprifoliaceae | Symphoricarpos Dunham. | snowberry |
| Caprifoliaceae | Viburnum L. | viburnum |
| Cornaceae | Cornus L. | dogwood |
| Cornaceae | Cornus mas L. | Cornelian cherry |
| Cuscutaceae | Cuscuta L. | dodder |
| Cuscutaceae | Cuscuta reflexa Roxb. | giant dodder |
| Grossulariaceae | Ribes L. | currant |
| Oleaceae | Ligustrum L. | privet |
| Oleaceae | Syringa X persica L. | Persian lilac |
| Rhamnaceae | Frangula alnus Mill. | glossy buckthorn |
| Rhamnaceae | Rhamnus L. | buckthorn |
| Rosaceae | Prunus L. | |
| Vitaceae | Parthenocissus quinquefolia (L.) Planch. | Virginia creeper |
| Vitaceae | Vitis vinifera L. | wine grape |
Distribution
Eupoecilia ambiguella is widely distributed across the Palearctic, where it is more common in cooler and humid climates. It has been reported from Brazil (EPPO 2007), but this record could not be verified. It is not considered established outside of Europe and Asia.
References
Bradley, J. D., W. G. Tremewan and A. Smith. 1973. British Tortricoid Moths - Cochylidae and Tortricidae: Tortricinae. The Ray Society, London, England.
EPPO (European and Mediterranean Plant Protection Organization). 2007. PQR, EPPO plant quarantine information retrieval system. Version 4.6 (2007/07) [accessed 28 Feb 2011].
Gilligan, T. M. and M. E. Epstein. 2011. The European grape vine moth not found in California: Eupoecilia ambiguella (Hubner)., pp. 32-34. In Plant Pest Diagnostics Center Annual Report 2010. California Department of Agriculture, Sacaramento, CA.
Meijerman, L. and S. A. Ulenberg. 2000. Arthropods of Economic Importance: Eurasian Tortricidae. Arthropods of Economic Importance series. ETI/ZMA.
Roehrich, R. and E. Boller. 1991. Tortricids in vineyards, pp. 507-514. In L. P. S. van der Geest and H. H. Evenhius [eds.], Tortricid Pests: Their Biology, Natural Enemies, and Control. World Crop Pests, Vol. 5. Elsevier, Amsterdam.
Razowski, J. 2009. Tortricidae (Lepidoptera) of the Palaearctic Region, Vol. 2, Cochylini. Frantisek Slamka, Slovakia. 195 pp.
