PMC INSECT TRAP

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common name: Grape vine moth

scientific name: Lobesia botrana (Denis and Schiffermüller), Polychrosis botrana (Insecta: Lepidoptera: Tortricidae)

Below:

Description

Biology

Life cycle

Damage

DESCRIPTION

Adult (photo 57,8 Kb): 18 to 20 millimetres wingspan. Long and thin antennae, pearly gray fore wings sprinkled with small reddish brown areas with 3 slightly slanted bands; one at the base, one at the center of the wing, broadened in its middle and one apical, quite dark bordered by a clearer zone. The grayish hind wings, with a darker marginal zone are bordered with gray bristles.

Egg: circular, of a diameter of 0.6 to 0.7 millimetres, slightly convex, whitish green with a rainbow hue.

Larva (photo 27,2 Kb): 8 to 9 millimetres, narrow, yellowish green to grayish green, brownish yellow head and thoracic plate; this caterpillar is very agile and moves about rapidly; when it is disturbed, it drops to the ground, suspending itself by a silk thread.

Pupa (photo 55,4 Kb): in a silken cocoon inside the bunch of grapes, in the folds of dry leaves, under the bark or the straw mulch as well as in the support-stake cracks or under earth mounds.

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BIOLOGY

Host plant: vine but also Daphne gnidium, a wild plant extremely common to the south of France and which seems to be its original host, as well as ivy (Hedera), privet (Ligustrum vulgaris), black currant, currant.

Adult (photo 57,8 Kb): active at night, the moth can fly several hundred meters and looks for dry places. The flights take place when the temperature is at least 14 degrees Celsius but under 31 degrees Celsius.

Lifespan: 10 to 12 days. Mating begins at nightfall and egg laying starts 2 to 3 days later. The first generation eggs are laid on the flower bud, sometimes on the bracts, the vine-shoots or the leaves, those of later generations on the grains.

Fecundity: 40 to 60 eggs.

Egg: development lasts 6 to 9 days for the first generation; itlasts only 4 to 6 days for the later generations, the temperature being higher.

Larva (photo 27,2 Kb): the first generation larva has a "strolling stage" of a few hours. After having slipped between 2 or 3 flower buds, it spins a few threads then perforates the flower envelopes and penetrates the bud; it may enter the peduncle of the bunch of grapes and cause the drying up of the bunch. The caterpillar is active and spins a relatively large sheath, difficult to detect. The caterpillar of later generations move about for only a few minutes and attack fruits: they web several fruits together with silk threads then nibble them or penetrate them.

Pupa (photo 55,4 Kb): development lasts 10 to 14 days. Over wintering occurs in the pupal stage, under the bark of the stump or in support-stake cracks.

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LIFE CYCLE

2, 3 and sometimes 4 generations depending on the region and whether the summer has been hot.

The moths appear from the end April until the end May depending on the regions, generally when the vine has 3 or 4 leaves. They emerge at intervals and the flights spread over 2 to 3 weeks. The caterpillar finishes its development at the time of flowering then pupates. The second flight takes place end of June-July; the more advanced caterpillars pupate and the third flight occurs between mid-August and the end of September.

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DAMAGE

Damage can be important: The caterpillars gnaw the almost ripe fruits and various moulds, in particular Botrytis, develop very rapidly on the wounds; the attacked fruits turn brown at the place of attack and rot. The presence of larvae (photo 27,2 Kb) and rotten fruits lowers the quality of the crop; moulds render vine making difficult and may require the crop to be harvested prematurely.

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