FEATURED INFORMATION

The European Grapevine Moth (Lobesia botrana)

Gonçal Barrios Sanromà
Government of Catalonia’s Department of Agriculture, Livestock, Fisheries, Food and the Natural Environment - Plant Protection Service

Lobesia botrana is the most important and widespread grapevine pest. What makes it a major pest is not only the direct damage and ensuing crop loss that it causes, but also the indirect damage caused by the wounds produced by larvae in grape berries, which can pave the way for infections from different types of grape rot (Botrytis cinerea, Rhizopus nigricans, Aspergillus niger, and sour rot) in suitable climate conditions.

There are three full generations a year, although with mild temperatures in late summer and early autumn there may be a partial fourth generation that can cause damage to late-harvested grape varieties. Currently, population monitoring and developmental surveillance ofLobesia botranatogether with pest control recommendations are an example of precision targeting adapted to Integrated Pest Management.

Lobesia botrana is the most important and widespread grapevine pest. What makes it a major pest is not only the direct damage and ensuing crop loss that it causes, but also the indirect damage caused by the wounds produced by larvae in grape berries, which can pave the way for infections from different types of grape rot (Botrytis cinerea, Rhizopus nigricans, Aspergillus niger, and sour rot) in suitable climate conditions.

There are three full generations a year, although with mild temperatures in late summer and early autumn there may be a partial fourth generation that can cause damage to late-harvested grape varieties. Currently, population monitoring and developmental surveillance ofLobesia botranatogether with pest control recommendations are an example of precision targeting adapted to Integrated Pest Management.

Monitoring methodology

Flight monitoring:
The following information is obtained using Delta-type pheromone traps:

  • Presence or absence of the parasite.
  • Flight data from the beginning to the end of each generation. This information is essential to identify when to start checking for eggs laid on the grapes.
  • Timing of product application to target the appropriate developmental stage of each generation.
Catch numbers for a given generation ofLobesia botranado not reflect the true population level: monitoring traps may catch large numbers while there is little egg-laying activity, and vice versa. The actual intensity of the infestation is determined by the number of eggs laid on the grapes. It should also be noted that the population level of one generation bears no relationship to the population level of the following generation.

Monitoring of egg laying:
This method is essential to determine the population level and the right timing of treatment with each product group. A group of grapes is closely followed in each monitored plot, with careful tracking of eggs, which develop in the following stages:
  • White or recently laid egg
  • Yellow or more developed egg
  • Black head, an egg in which the dark colored head capsule is visible; hatching will occur within a few hours.
  • Penetrations of fruit by neonate larvae.
The percentages of the different stages observed allow us to determine, with enough accuracy for each generation, the timing of current treatments used to control this pest.Beginning of flightBeginning of egg-layingBeginning of hatchingPeak hatchingOnce the damage has been done, focal points are counted to find out the level of attack. From birth until they reach maximum development, the larvae move in and out of adjoining berries, forming focal points. A focal point reflects the activity of a single larva. There is significant variability in the number of adjoining berries a single larva can penetrate, and we can find focal points consisting of anything from 2-3 to 8-10 damaged berries.

With the data collected, the most effective way of discovering the level of infestation is to count the eggs and the focal points produced by berry penetration, specifically:
  • Percentage of grapes affected, which indicates the level of infestation
  • Number of focal points per 100 grapes, either in the form of eggs or in the focal points of penetration made by each larva, which indicates the number of individuals and therefore the intensity of the infestation.
Control systems

Chemical control
Traditionally, phosphorus compounds were used and were to be applied on the days with the highest number of larvae births. The current situation is very different: very few of these products remain authorized, and the new active substances only have an impact at very specific moments in the biological cycle. Whilst this limited activity is actually good news, since it means the substances are much more selective and therefore the impact on other insect fauna is reduced, it also necessitates very accurate timing. The current recommended application times for different products are as follows:
  • Beginning of flight
  • From the beginning of flight to the beginning of hatching (the egg-laying period)
  • The very start of hatching, defined as the time when the first eggs with a black head are detected.
  • Hatching peak, defined as the period from 30% to 80% hatched eggs.

Since individual products focus on only one of these periods, using them outside that period significantly reduces effectiveness.Current advice is to treat the second and third generations, and only in exceptional cases treat the first. Agricultural Warning Stations and Plant Protection Associations (ADV) in Catalonia notify pest stages in each wine-growing area, so farmers must choose in advance the product to be used and wait for the corresponding notification.

Mating disruption
Following years of work in different parts of Spain, a mating disruption technique has been developed in the fight against Lobesia botrana. However, for this to be really effective a number of requirements must be fulfilled:

  • In our experience, the minimum area should exceed 40 hectares, and at least 80 hectares in windy areas. The larger the surface area, the lower the effect reduction at the borders, which ensures greater overall efficiency. This surface area should be as homogeneous as possible, with mating disruption applied to all encompassed plots of land.
  • The lay of the land is important: this technique works best in flat areas.
  • Emitters should be placed when the first catches of a given generation are detected, often just before bud break, and should be distributed evenly across the surface, keeping to the recommended density per hectare.
  • Emitter density may be reduced after a few years of high effectiveness. Still, emitters should always be placed over large surface areas, centrally sited, and set to an hourly release rate of no less than 25 mg/hectare.
  • It is important to identify problem areas in the mating disruption zone, whether these are external borders or internal ones. Such problem areas should be tackled locally if they arise, to avoid an increase in following generations.
  • This technique can be highly effective at present, allowing for a very high treatment threshold: currently, 10% of grapes affected.

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Data protection policy

In accordance with the Organic Law on the Protection of Personal Data 15/1999, of 13 December, Promotora de Exportaciones Catalanas SA (hereinafter PRODECA), whose address is Gran Via de les Corts Catalanes, 620, principal, 08007 Barcelona, with tax reg. no. NIF A58241316, declares that the images contained on the website www.smartfruitcongress.cat are included in a file belonging to PRODECA. The purpose of this file is the promotion, via its website, of the activities conducted by PRODECA – SmartfFruit IPM International Congress.

PRODECA guarantees that you may, at any time, exercise your right to access, rectify, cancel or oppose by writing to the aforesaid postal address, using the reference "PROTECCIÓN DE DATOS - SMARTFRUIT", or to the email address smartfruitcongress@smartfruitcongress.cat.

Specifically, to correctly exercise these rights you must clearly provide the following items in that communication:
- Name, surname(s) and photocopy of National Identity Document or Passport.
- Statement of the purpose of the request.
- Address for notification purposes.
PRODECA also declares that it reserves the right to delete from its website any content that it considers violates current and applicable legislation.

D’acord amb l’article 17.1 de la Llei 19/2014, la ©Generalitat de Catalunya permet la reutilització dels continguts i de les dades sempre que se'n citi la font i la data d'actualització i que no es desnaturalitzi la informació (article 8 de la Llei 37/2007) i també que no es contradigui amb una llicència específica.