Grapevine Moth: All You Need to Know for Healthy Vines

The European Grapevine Moth (Lobesia botrana or EGVM) is a significant agricultural pest that poses a threat to grapevines worldwide. Originating in Europe, the moth has caused considerable damage to grapes and other berries globally, with its presence first detected in the United States in 2009 before being officially eradicated in 2016. This pest is particularly destructive due to its ability to feed on the flowers and fruits of the host plant, often targeting grapes.

One of the primary concerns associated with the grapevine moth is the potential for vineyard powdery mildew outbreaks. These outbreaks can be tackled through a high volume application of water mixed with a wetting agent, which works by washing off all the spores from the grapevine and preventing further dispersal to healthier parts.

As grapevine moth infestations can lead to severe losses in grape production, it is crucial for vineyard owners and growers to be aware of the various preventative and control measures. Such measures can include monitoring moth populations, monitoring vineyards for signs of infestation, and implementing appropriate management practices.

Grapevine Moth Overview

Identifying the Grapevine Moth

The European Grapevine Moth (EGVM), or Lobesia botrana, is a type of pest from the Tortricidae family. Native to southern Italy, they are found in several other regions, including Europe, the Middle East, Africa, and even the United States. These moths were first detected in Napa County, California in 2009source. Key identifying features of the European Grapevine Moth include:

• Adult moths are about 1/4-inch long
• Wing color depends on the region they are found in, ranging from brownish-gray to light brown with dark markings
• Larvae are small and yellowish-green in color with a brown head

Life Cycle of the Grapevine Moth

The life cycle of the European Grapevine Moth consists of four stages:

1. Egg: Female moths lay eggs on the buds of the grapevine. Eggs hatch after about 3-6 days.
2. Larvae: The larvae feed on the grapevine’s flower or fruit, causing significant damage. Their feeding period lasts around 21-28 days.
3. Pupa: Following the feeding period, the caterpillars form a cocoon and pupate, which takes around 10-20 days.
4. Adult: Adult moths emerge from the cocoon and continue the life cycle by laying eggs.

The European Grapevine Moth’s life cycle is impacted by the climate, with warmer temperatures causing faster development. In summary, the European Grapevine Moth is a significant pest that poses a threat to grapevines worldwide. Recognizing its identifying features and understanding its life cycle can greatly assist in pest control efforts.

Damage and Symptoms of Infestation

Effects on Grapevine Berries and Clusters

The European Grapevine Moth (Lobesia botrana) causes significant damage to grapevines, primarily by feeding on the berries, flowers, and fruits. When adult moths lay their eggs on grape flowers or developing fruit, the hatched larvae feed on these host plants, causing substantial harm ¹.

• Berries: Larvae burrow into the berries and consume the interior, causing them to lose their skin and seeds, eventually withering away ².
• Flowers: The moth feeds on this crucial reproductive part of the plant, affecting overall fruit production.

Impact on Grape Production

The damage caused by the European Grapevine Moth negatively impacts grape production in several ways:

1. Quantity: As the larvae feed on flowers and developing fruits, the overall yield of grapes is significantly reduced.
2. Quality: Affected grape clusters may have an increased presence of rot and fungal infections due to the larvae’s activity ³.

A comparison of healthy grapevines and those infested with the European Grapevine Moth:

In conclusion, the European Grapevine Moth poses a considerable threat to grapevines, mainly through its damaging effects on grape berries, flowers, and fruit production. Understanding these symptoms enable early detection and appropriate management techniques to mitigate the pest’s influence on grapevines.

Control and Management of Grapevine Moths

Mating Disruption and Biological Controls

• Mating disruption techniques involve using pheromones to confuse male grapevine moths and prevent mating.
• Specific parasitoids such as Dibrachys spp. can help control European grapevine moth populations by attacking their larvae.

Grapevine moth control can begin with non-chemical methods, such as mating disruption and biological controls. Mating disruption uses pheromones to disrupt the communication between male and female moths, making it difficult for them to find each other and mate¹. Biological controls, such as introducing natural enemies like parasitoids, can also help manage grapevine moth populations. For example, the parasitic wasp species Dibrachys spp. is known to attack the larvae of the European grapevine moth³.

Chemical Control and Insecticides

Common insecticides:

• Insect growth regulators (IGRs)
• Spinosyns
• Bacillus thuringiensis (Bt)

Chemical control methods involve the use of insecticides, which can effectively manage grapevine moth populations when applied correctly and at the right time. Some common insecticides for grapevine moth control include insect growth regulators (IGRs), spinosyns, and Bacillus thuringiensis (Bt)².

IGRs, as the name suggests, interfere with the growth and development of insects, making them unable to reproduce. Spinosyns are another group of insecticides derived from a naturally occurring soil bacterium; they target the nervous system of insects and are generally considered safe for non-target organisms⁴. Bacillus thuringiensis (Bt) is a naturally occurring soil bacterium that produces a toxin harmful to certain insects, including grapevine moths⁵. Bt can be applied as a biological insecticide to control larval populations.

Insecticide pros and cons:

Pros:

• Effective in controlling grapevine moth populations
• Can be applied in a targeted manner to minimize impact on non-target organisms

Cons:

• Can cause resistance in pests if used improperly
• May negatively affect beneficial insects and other non-target organisms

While insecticides can be effective, it is important to use them responsibly to prevent the development of resistance in pests, minimize harm to beneficial insects, and limit the impact on non-target organisms. The University of California’s Integrated Pest Management program recommends monitoring vineyards for grapevine moth presence and damage, and then applying insecticides when necessary⁶.

Geographical Spread and Quarantine Measures

Global Distribution of Grapevine Moths

The European Grapevine Moth (Lobesia botrana) is a significant agricultural pest, predominantly found in:

• Europe: Native region
• Mediterranean: Widespread presence
• Southern Russia: Invasive species established in vineyards
• Japan: Limited distribution
• Middle East: Regional infestations
• Near East: Sporadic occurrences
• Northern and Western Africa: Non-native invader species (source)

The moth is particularly harmful to grapevine crops due to its larvae feeding on flowers and fruits, resulting in severe crop loss.

Quarantine and Detection Methods

The United States had its first detection of the European Grapevine Moth (EGVM) in California in 2009. Through rigorous quarantine efforts, the country successfully eradicated the pest by August 2016 (source).

Some common detection methods and practices are:

• Pheromone traps: Attracts male moths for monitoring population trends
• Visual inspections: Examination for eggs, larvae, and crop damage
• Annual surveys: Ongoing efforts to monitor and prevent new infestations

In addition, biological control measures using parasitic wasps have proven effective in reducing EGVM populations. These wasps are natural enemies of the moth, targeting their eggs and larvae.

Comparing the two main generations of EGVM, researchers found the first generation affects flowers, while the second generation feeds on grape berries. Control measures must be adjusted accordingly to counter the moth at each stage of its lifecycle.

Prevention Strategies and Resources

Best Practices for Vineyard Management

• Monitor vineyards: Regularly check for signs of infestation such as webbing, larvae, and damaged berries. This helps in early detection and prevention of grapevine moth damage.
• Pruning and canopy management: Proper pruning and canopy management allow for better air circulation and sunlight penetration, reducing the risk of infections and moths finding a suitable habitat.
• Remove infested berries: Remove and destroy any infected green berries or grape clusters to prevent larvae from developing and spreading.
• Use reduced-risk insecticides: Apply reduced-risk insecticides when necessary to control grapevine moth populations. Examples include neem oil, which targets adult moths, and other compounds that target the Lepidoptera group.

Available Guidelines and Restrictions

• USDA APHIS: The United States Department of Agriculture provides guidelines and resources for managing European grapevine moth infestations.
• UC IPM: The University of California Statewide Integrated Pest Management Program (UC IPM) offers research-based information on grapevine moth identification, monitoring, management, and treatment options.
• CDFA: The California Department of Food and Agriculture (CDFA) provides up-to-date information on European grapevine moth detections, regulations, and control efforts in California.

A consistent and well-planned prevention strategy can help reduce the risk of grapevine moth infestations and the associated damage to grape production. Utilize the provided resources and guidelines, and tailor them to your vineyard’s specific conditions to maintain a healthy crop.