There vine moth (Lobesia botrana) is the most dangerous parasite for Italian viticulture. The presence of this vine moth it mainly affects the central and southern regions of the country, but a potential infestation cannot be underestimated in the north as well. This insect has a specific biological cycle and it is its larvae that produce the greatest damage to the vine plant.
In this article we describe the different stages of this moth and its life cycle. Let’s also look at the monitoring and sampling techniques. Finally, let’s understand the defense techniques to be implemented in the vineyard for eliminate the moth without the use of chemical pesticides.
Description of the vine moth
The vine moth is an insect of the order of Lepidopterafamily of the Tortricidesgenus Lobesiaspecies L. botrana.
Let’s see its morphological characteristics, useful for the winegrower for identification.
Adult vine moth
- it looks like a little butterfly;
- it has a wingspan of about 10-12 mm;
- marble-like fore wings, with brown spots alternating with other greyish ones;
- presence of a characteristic dark band that crosses the wing in the middle part, which narrows from the outside towards the inside.
Vine moth eggs
- lenticular form;
- small size (0.7 x 0.6 mm);
- color first yellowish, then light gray;
- the deposition takes place in isolation on the flower buds or on the berries.
Vine moth larva
- when born it is whitish in color;
- color that turns to yellow-green and finally to brown;
- when fully ripe it is 9-10 mm long;
- head of yellow-brown color;
- the larva crosses and turns into a butterfly
- brown chrysalises, 4-6 mm long.
Life cycle of the insect
The vine moth overwinters as a chrysalis in a silky cocoon. It does this by repairing itself in the crevices of the bark of the stump or in the cracks of the stakes supporting the plant itself. The first flight of adult butterflies takes place between the second half of April and throughout the month of May. Mating takes place immediately, mainly in the twilight hours. The next phase is that of oviposition which occurs on the floral buttons, on the pedicels and on the rachis.
First generation
After 7-14 days of incubation, the first generation larvae are born, called antofaghe. These larvae erode the flowers, wrapping them with silky threads to form typical glomeruli. Their activity lasts more or less 20 days, so they always cross on the bunch.
Successive generations
Second flight adults originate from these grapevine moth chrysalis in summer (from mid-June to July). These lay their eggs on the now well-formed grapes, giving way to the second generation larvae, called carpophages. The latter give rise either to the wintering pupae (in the northernmost regions) or to a third generation. In this case, adults flicker from August to the end of September, depending on the climatic bands. These eggs lay on the grapes in the ripening phase. Therefore, the vine moth usually completes 2-3 generations a year, which in some very favorable seasons can reach 4 (extreme southern regions).
What plants does it affect?
In addition to the vine, the Lobesia botrana it can also be found on other plants of the Mediterranean scrub. In particular currant, olive tree, viburnum, privet and honeysuckle. However, the moth is a parasite that particularly worries the vine.
Damage to the vine caused by moth
The extent of damage to the vine by the moth varies depending on the phenological phase of the plant. The first generation larvae they concentrate trophic activity on the clusters of flowers, destroying a part of them to build the nest. This damage is the least serious, since, usually, the attack is not very massive. Furthermore, the loss of some flowers is compensated by the larger size of the grapes in the cluster.
The greatest damage is caused by the larvae of second and third generation, which attack the berries directly, penetrating and emptying it. From the outside you can see the entrance and exit holes. The grape turns brown and withers.
Further damage to the cluster is caused by the formation of nests: small silky cocoons located within the cluster itself.
The third generation also causes indirect damage, as the grapes are in the final ripeness, therefore more delicate. The attack makes them more susceptible to serious conditions such as botrytis and acid rot.
Climate favorable to vine moth infestations
The vine moth causes the greatest damage in very dry areas. In rainy environments and with high humidity its presence is limited. Unfortunately, spring and summer drought is an increasingly frequent environmental condition. In the years, the Mediterranean is turning into an arid regionThis condition favors the presence of high populations of moth.
How to get rid of the vine moth
In vineyards conducted organically, characterized by a high degree of biodiversity, the vine moth can be controlled by beneficial insects. Spiders (arachnids), forficule (skin bacteria), chrysopid neuropterans, hoverflies and tachinidae dipters, and hymenoptera, are good predators of moth larvae and eggs. A vineyard where thegrassing favors the presence of these antagonistic insects.
Traps for monitoring
For eliminate the vine moth with the biological struggle, we start from its carefulness monitoring. This is done by placing traps in the vineyard activated with the sexual aggregation pheromone. The one for the vine moth is available in specialized stores, and has a low cost. The operation of monitoring traps it’s not complex. In short, they must be placed in the vineyard starting in early April and replaced following the pheromone’s expiration indications. Typically, two traps are used per hectare of vineyard, so their cost is sustainable. The trap gives us an indication of the presence of the moth, so as to organize the interventions. Normally no action is taken on the first generation larvae.
Bacillus thuringiensis
In organic viticulture the most effective product in the control of the vine moth is the bacillus thuringiensis. Only the kurstaki variety (found here), it is good not to be confused with the other varieties of bacillus, useless on this parasite. It is a very selective organic insecticide, and is effective on moth larvae in the early stages of life. It acts by ingestion, so it must reach the moth larvae before they enter the berries. For this reason it is used for second and third generation larvae. Thanks to the capture traps we can calibrate this intervention.
How to intervene
For the second generation larvae, Bacillus thuringiensis is sprayed on the plants twice: the first at 7-9 days from the moment of the growing phase of capture in the traps; the second after 15-16 days (7 days after the first treatment).
For third generation moth larvae, only one intervention is done, after 14-21 days from the beginning of the catch with monitoring traps. To improve the effectiveness of the bacillus against the moth, about 1 kg of sugar is added for every 100 l of water.
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