Tortrix viridana

Status

EXOTIC

PORT INTERCEPT

Taxonomy

Tortrix viridana Linnaeus (Tortricidae: Tortricinae: Tortricini)

Common names: European oak leafroller, green oak tortrix

Synonyms: coeruleana (Tortrix), flavana (form), pflegeriana (form), suttneriana (Tortrix)

Adult Recognition

FWL: 8.0–11.0 mm

Forewing unmarked, uniformly green. The exact color varies from bright green to dull pale green, and some individuals have dull-yellow forewings, a condition that can also be caused by exposure of specimens to various killing agents and prolonged sunlight.

Male genitalia are distinguished by the following characters: uncus absent; socii large; valva sub-rectangular with well developed sacculus. Female genitalia are characterized by broad papillae anales with a patch of flat-headed setae, short apophyses, a long ductus bursae, and a small signum in the corpus bursae.

Larval Morphology

The following account is summarized from Bradley et al. (1973)Bradley et al. (1973):
Bradley, J. D., Tremewan, W. G., Smith, A. 1973. British Tortricoid Moths, Cochylidae and Tortricidae: Tortricinae. The Ray Society, London. 251 pp..

Late instar larvae are approximately 15–20 mm long with a green to gray abdomen. The head varies in color from brown to black and the prothoracic shield varies from near-translucent to black. Darkened pinacula, which are more prominent near the anterior end of the abdomen and on the thorax, serve to separate this species from many North American tortricid larvae. Other diagnostic characters include black thoracic legs and an anal comb with eight teeth.

A detailed description of larval chaetotaxy is available in Swatschek (1958)Swatschek (1958):
Swatschek, B. 1958. Die larval systematik der wickler (Tortricidae und Carposinidae) aus dem zoologischen Institut der Universitat Erlangen. Akademie-Verlag, Berlin. 269 pp. [Abhandlungen zur larvalsystematik Insekten 3.]. 

Similar Species

Adults of this species are unlikely to be confused with any other tortricid. In Europe, Tortrix viridana is similar both in size and coloration to Earias clorana (Nolidae).

Distribution

Tortrix viridana is found in Europe, Asia Minor, the Middle East, and northern Africa.

Biology

The following account is summarized from Bogenschütz (1991)Bogenschütz (1991):
Bogenschütz, H. 1991. Eurasian species in forestry, pp. 673-709. In: van der Geest, L. P. S., Evenhuis, H. H. (eds.), Tortricid Pests: Their Biology, Natural Enemies, and Control. World Crop Pests, Vol. 5. Elsevier, Amsterdam..

Tortrix viridana typically completes a single generation per year. In warmer regions, two generations can occur. Adults are present from May until early July over most of its range.

Females lay eggs during June and July in the crown of the host tree; eggs are laid in pairs for a total of 50–60 per female. Reproduction may be able to occur parthenogenically (du Merle 1999du Merle 1999:
du Merle, P. 1999. Deacute;veloppement partheacute;nogeacute;neacute;tique chez la Tordeuse verte du checirc;ne, Tortrix viridana L. (Lepidoptera, Tortricidae). Bulletin de la Socieacute;teacute; Entomologique de France. 104: 85-90.). The eggs overwinter and larvae hatch the following April and May. First instar larvae feed on open buds and subsequent instars feed on the leaves. Larvae complete five instars and pupation occurs in a folded leaf.

Oak (Quercus sp.) is the primary host and in outbreak conditions T. viridana can cause extensive defoliation of oak trees. Defoliation affects tree growth, reproduction, and increases the chances of damage by other insects and frost. This species is regarded as one of the most important tortricid forest pests in southern Europe.

Secondary hosts include blueberry (Vaccinium sp.), nettle (Urtica sp.), and possibly other species not listed here; records on Norway spruce (Picea abies), poplar (Populus sp.), and raspberry (Rubus sp.) could not be verified.

Plant Associations

View full screen host table here