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Agricultural entomology: Moth of the vine

Agricultural entomology: Moth of the vine


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Classification and host plants

Class: Insects
Order: Lepidoptera
Suborder: hetoneuri
Family: Tortricides
Genus: Lobesia
Species: L. botrana (Denis et Schiffermüller)

Bibliographic reference:
Phytopathology, agricultural entomology and applied biology” – M.Ferrari, E.Marcon, A.Menta; School edagricole - RCS Libri spa

Host plants: Vine, Currant and other spontaneous plants marginal to the vineyards.

Identification and damage

The Tignoletta della Vite is an insect widespread throughout Italy but especially in the warmer central-southern regions; it is among the most dangerous insects, together with the Moth, which attack the Vine. The butterfly, whose dimensions are about 10-12 mm of wingspan, is gray-yellow and blue variegated gray: the livery is intensely marbled.
The larvae (9-10 mm long) at the first ages are ocher-hazel colored with a dark head, then the body becomes darker green-brownish and the head becomes lighter.
The damage is determined by the larval stage. The larvae of the first generation attack the flower clusters (antophagous generation), feed on the single flower buttons also building silky nests, visible on the inside of the bunch; this generation is not very harmful either because the damage to individual flowers is bearable (for some tight cluster varieties it could also be good), and because the attack is generally never massive. The larvae of the second generation are more dangerous because they feed on the berries (carpophagous generation), entering and emptying them. The attack is evident in that the berries wither and darken; upon closer inspection, the entry or exit holes and possibly also the larvae that take shelter in more or less loose whitish silky shelters built inside the cluster are noted. In some northern regions there are only 2 generations, but in most cases Lobesia also completes a third generation; these larvae behave like the previous one, attacking the berries.
In these cases, the generation takes place in late summer, when the berries are in the ripening phase, and is even more dangerous due to the complications of a fungal nature (botrytis and acid rot) that can occur on the wounds caused by the larvae.

Biological cycle

The Tignoletta della Vite overcomes the winter in the chrysalis stage in a small whitish cocoon between the ravines of the Corte del Vite, any braces and at the base of the plants.
The first adults appear from April to May; immediately mating occurs and the females lay on the flower bunches.
The first generation larvae (antophagous larvae) will be born from the eggs; their activity lasts about 3 weeks, then they become incisal in the bunch, originating, at the beginning of the summer (mid-June-July), the second flight adults who lay on well-formed berries, giving rise to the second generation larvae (carpophagous larvae).
These, after their activity on the berries, can originate the wintering chrysalis (in some northern regions) or more frequently produce a third generation. In the latter case, the flicker of adults will occur from August until the end of September, depending on the environment.
The Tignoletta makes, therefore, 2-3 generations per year.

Vine Moth adult - Lobersia botrana (Denis et Schiffermüller) (photo IASMAA - Trento)

Larva di Tignoletta - Cluster infested with botrytis following the larval activity of the moth
(photo IASMAA - Trento)

Fight

The fight against the Moth of the Vine is carried out, currently, with guided fighting techniques that are based on the monitoring performed either with sampling techniques or with the use of sexual traps. You can also follow the indications of the provincial or zonal integrated struggle bulletins.

Sampling technique
The sampling is carried out by checking the bunches (about 100 per hectare of vineyard), randomly chosen on the branch, on a number of strains randomized on the field.
Sampling must be carried out in three pre-established periods which correspond more or less to the three generations; in particular at flowering (the generation), from the pinky to the pre-closure of the bunch (2nd generation) and from the veraison to the first half of September (3rd generation). With sampling the intervention thresholds are:
- 1st generation: 35-50% of infested bunches;
- 2nd generation: it is possible to intervene in the first attacks on grapes, in areas at risk; or with a threshold of 5% of bunches infested with larvae or in the presence of eggs or with penetration holes;
- 3rd generation: action is taken at a threshold of 5% of infested bunches.

Use of sexual traps
The intervention threshold can also be determined through the use of sexual traps for monitoring. These must be installed (1 or 2 per hectare or per farm) in early April; it is necessary to change the hormonal capsule, and possibly also the fund, about 10 days before the expected flight of the next generation.
Generally the catches of the first generation are only indicative of the existing population (it is not convenient to deal).
For the other generations the indicative threshold proposed in some environments is 15-20 males caught per trap per week (e.g. traptest).
If you do not want to consider the intervention threshold, you can treat it about 10-12 days after the first catches, if only one treatment is sufficient; or it can be treated at 9-13 days, with a subsequent intervention after 7 days, from the moment in which the phase of capture of the males is increasing.
The intervention is also activated upon exceeding the threshold of the infested bunches, or at the first damage on the grapes.
Guided fighting can also be carried out with biotechnological products, in fact biological formulations based on Bacillus thuringiensis ssp can be used. kurstaki.
This biological insecticide, in consideration of its characteristics, must be distributed before the larvae have entered the berries; it is used with good results against the larvae of the second generation, distributing it twice (the first 7-9 days and the second 15-16 days from the beginning of the growing catch phase) or once only between the 19th and the 13th day since the beginning of the growing catch phase. Against the third generation, it applies 2 to 3 weeks after the start of the male catch. In these interventions, to improve the effect of the treatment, it is advisable to add about 500-1000 g of sugar per hectolitre of water.
In addition, preparations based on viruses and fungi are being tested (microbiological struggle), which seem to have activities against some Tortricides including Lobesia, and techniques of sexual confusion.
Finally, among the entomophages, some parasitoid Hymenoptera (Chalcidoid and Icneumonides), the Tachinid Diptera and the Chrysopids, these last good auxiliary egg predators.


Video: Agricultural Entomology-1 Nemraj Sunda (May 2022).