Author: (Hübner, 1796)
European grape berry moth
Species Overview:
Adult: wingspan 12-15 mm; forewings pale ochreous, extensively suffused and strigulated with yellow-ochreous, with a contrasting heavy median fascia; costa and dorsum strigulated or dotted with black.
Egg: opalescent, greyish brown when first laid, later becoming spotted with bright orange. Single eggs are laid on or near the food source of the neonate larvae: in spring on bracts, petals and stems of the flower clusters and in summer on the berries.
Larva: head, prothoracic plate and thoracic legs dark brown or shining black; abdomen shagreened, varying from olive-green to reddish brown or brownish yellow; pinacula brown, large and moderately prominent; anal plate varying from brown to yellow [E. ambiguella larva ]
Pupa: reddish brown; in a leaf-case amongst ground debris or attached to a stem of the food plants.
Taxonomic Description:
Male:
Eupoecilia ambiguella adults
Eupoecilia ambiguella male
External characters: Labial palpi ochreous-cream, head and thorax cream, abdomen brownish. Antenna shortly ciliate. Forewing only slightly dilated posteriorly; ground colour pale ochreous-white, extensively suffused and strigulated with yellow-ochreous, costa and dorsum strigulated or dotted with black, costa narrowly suffused with fuscous-black from base to beyond middle (outer margin of median fascia); markings dark grey; basal and sub-basal fasciae obsolescent, indicated only by costal striae; median fascia conspicuous, inwardly oblique, dilated on costa, diffusely strigulated or mixed with blackish, a variable ferruginous admixture above and below median fold, sometimes extending to dorsum; pre-apical spot obsolescent, indicated by weak costal striae; apex variably suffused with blackish; a small diffuse blackish spot in terminal margin near middle; cilia pale ochreous, a dark sub-basal line. Hindwing grey, paler basally; cilia light grey, with a dark sub-basal line (Bradley et al., 1973; Razowski, 1970a).
male genitalia E. ambiguella
Genitalia: Socii expanding towards base such that bases touch each other; thin narrow terminals of socii situated laterally on broad bases. Vinculum divided ventrally, forming two sclerites. Caudal margin of valva oblique; sacculus broad at base, narrow beyond base, with short spinules on raised terminal portion; transtilla with strong median process. Aedeagus large, with one large thin cornutus and many small cornuti, arranged in three groups: 2 smaller groups and one in which the cornuti are arranged in a ring. In the latter group, the cornuti have plate-shaped bases.
Female:
External characters: Forewing markings similar to those of male; hindwing more uniformly grey.
female genitalia E. ambiguella
Genitalia: Antrum very short, broad, connected to sterigma. Ductus bursae short, distal part membranous with many small denticles, anterior part sclerotized, reaching into the corpus bursae, covered with denticles. Anterior part of corpus bursae membranous.
Biology:
In mainland-Europe, where this species has two or more generations, the larva is a pest on grapevine (Vitis vinifera). In the spring the larva spins the flowers and flowerheads of the vine and is known as "Heuwurm"; in late summer the larva lives in the fruits and is known as "Sauerwurm" (Swatschek, 1958; Bradley et al., 1973).
After hatching the larvae penetrate the flower buds or berries. The mature larvae leave the clusters and weave their cocoons, the non-diapausing ones mainly on the edges of the leaves, the diapausing ones in the bark of the trunks. They overwinter as diapausing pupae. Moths are crepuscular insects. They feed in the evening and early in the morning, mate after midnight until early morning, and lay eggs in the afternoon and evening (Roehrich and Boller, 1991).
In England, this species has only one generation yearly. Larvae occur in July and August, feeding on the berries of Frangula alnus, living within a berry and eating the pulp and seeds, usually attaching the berry to a leaf. In later instars the larva may move to a fresh berry or join two or three berries together with a silken tube. When full-grown in the autumn the larva leaves the feeding place and constructs a case from leaf fragments, either amongst debris on the ground or attached to a stem of the food plant, overwintering in the case, but sometimes pupating in the autumn. Moths fly in from the end of May to June (Bradley et al., 1973).
Host plants:
Acanthopanax, Acer campestre, Cornus mas, Frangula alnus, Fraxinus, Hedera helix, Ligustrum, Lonicera, Prunus spinosa, Ribes, Symphoricarpus, Syringa persica, Viburnum, Vitis vinifera.
Also recorded as a pest of lemon (Citrus).
Roehrich and Boller, 1991, mention that in vine-growing areas, larvae are only rarely found on reported host plants and seem to be restricted to grapevine.
Damage:
Damage depends strongly on the developmental stage of the grapevine. Before and during flowering the larvae at first penetrate single flower buds and later on start to tie together several flower buds, building shelters in which they stay and continue their feeding activities. In this stage the tolerance level for infestation is relatively high and depends on the ability of the grape variety to compensate the damage. For example, the cultivar 'Cabernet Sauvignon' can tolerate up to two larvae per flower cluster without reduction of yield. Experiments simulating larval damages by artificial removal of increasing numbers of flower buds showed that cultivars with smaller flower clusters, such as 'Riesling x Sylvaner' or 'Pinot noir', can tolerate only one larva per cluster. Consequently, the tolerance level implemented in various countries varies between 15 and 100 larvae per 100 flower clusters.
The larvae of the summer generations infest the grape berries. The most serious damage is not necessarily caused by the actual destruction of a few berries by the larva but by the fungus Botrytis cinerea Persoon, which develops readily on the injuries caused by the larvae. The economic thresholds during this period depend on various aspects, such as whether the grapes are produced as table fruit or for vinification, the level of precipitation (higher or lower risk of Botrytis infestation) and the quality and price level of the crop. In the different European countries and regions it varies between 2 and 20 larvae per 100 grapes (Roehrich and Boller, 1991; Remund and Siegfried, 1982).
Distribution:
Widespread in the temperate zones of the Palaearctic and Indo-Oriental Regions.
Their abundance in the various viticultural areas is not uniform but can change within relatively short distances: in certain places they can cause heavy damage every year, in other areas the populations are always low, and there are also areas where the abundance changes from year to year according to the local climatic conditions.
Pheromone:
Z9-12Ac : 100 *
E9-12Ac : 0.5
D9,11-12Ac : 0.2
12Ac a : 3 *
Z9-12OH : 8
16Ac : 10
18Ac : <2000 *
20Ac : 40
Components marked with * are involved in attraction (Arn et al., 1986b).
Attractantia:
Z 9-12Ac : 1
12Ac : 1
18Ac : 2 (Arn et al., 1986b)
Parasitoids:
Dibrachys affinis Masi can parasitize up to 85% of the diapausing pupae. However, studies conducted in Spain showed that adults of this antagonist emerge too early in spring and that they are not present in pupae of the first two generations.
Trichogramma dendrolimi Matsumura, Trichogramma semblidis (Auriv) and Trichogramma maidis Pint. et Voeg. (Trichogrammatidae) parasitize the eggs.
Also recoreded from Eupoecilia ambiguella:
Itoplectis maculator Fabricius (Ichneumonidae)
Itoplectis alternans Gravenhorst (Ichneumonidae)
Ephialtes sagax Hartig (Ichneumonidae)
Habrocryptus alternator Gravenhorst (Ichneumonidae)
Agrypon flaveolatum Gravenhorst (Ichneumonidae)
Angitia fenestralis Holm. (Ichneumonidae)
Campoplex difformis Gmelin (Ichneumonidae)
Ascogaster quadridentata Wesmael (Braconidae)
Ascogaster rufidens Wesmael(Braconidae)
Monodontomerus aereus Walker (Chalcididae)