Ginkgo thrips

Ginkgo thrips (Scirtothrips ginkgoe) belongs to the order Thysanoptera and the family Thripidae. These are minute insects, often measuring only 1–2 mm, which makes them difficult to detect without careful inspection.

Adult insects have slender, pale or yellowish-brown bodies that provide excellent camouflage against leaf surfaces. Their most distinct feature is the presence of narrow wings fringed with long hairs, giving them a feather-like appearance.

The larval stages resemble the adults but lack wings and appear smaller and lighter in color. They are highly active and usually congregate on the undersides of the leaves to feed.

This species is highly specialized, primarily affecting ginkgo trees. Initial infestations are often overlooked because the insects hide within the crevices of developing buds or young foliage.

For accurate identification, experts recommend using a magnifying glass or the "tap test," where a branch is shaken over a white sheet of paper to dislodge the insects for inspection.

The primary host for this pest is Ginkgo biloba. The thrips prefer feeding on the sap of young, actively growing shoots and tender leaves that are rich in nutrients.

While specialized to ginkgo, high populations of this pest can occasionally spill over onto other ornamental trees and shrubs in nursery environments.

The damage is most severe during the peak growth phases of the plant. As they feed, they puncture the epidermal cells, causing the leaf tissue to collapse and lose its vitality.

In greenhouses or controlled garden environments, the host range can expand due to the consistent climate, which allows for year-round breeding cycles.

Extensive feeding leads to severe stress in the host tree, making it significantly more susceptible to secondary infections, such as fungal pathogens or environmental stressors.

The activity of Scirtothrips ginkgoe is strictly regulated by temperature. Infestations typically begin in early spring once temperatures are warm enough to support larval development.

Summer is the peak season for these pests. Hot, dry weather accelerates their reproductive cycle, allowing populations to explode within a relatively short period of time.

During the peak summer months, damage becomes most visible. Agronomists should conduct regular monitoring during this period to prevent irreversible damage to new growth.

As autumn approaches and temperatures drop, the metabolic rate of the thrips decreases. They seek overwintering sites in bark cracks or under leaf litter to survive the winter.

Depending on the climatic zone, there may be several generations per year, necessitating a sustained management approach throughout the entire vegetation season.

The earliest signs of an infestation are small, pale or silvery spots on the leaves. Over time, these spots coalesce, leading to widespread necrosis of the leaf tissue.

Infested leaves begin to curl, deform, and yellow. The damaged areas lose their ability to perform photosynthesis, which stunts the overall growth of the plant.

Tiny black droplets, which are the excrement of the thrips, are frequently visible on the underside of the leaves and serve as a diagnostic indicator of their presence.

Severe infestations often result in brown, withered patches, significantly reducing the aesthetic value of the ginkgo trees in landscapes and nurseries.

• Deformed or stunted terminal shoots.
• Premature leaf drop in young trees.
• Silvering or bronzing of leaf surfaces.

Effective management begins with good horticultural practices, such as removing weeds around the base of trees and maintaining proper irrigation to reduce plant stress.

Chemical control involving systemic insecticides is often necessary when infestations are severe. These products are taken up by the plant, making it toxic to the sap-feeding insects.

Blue sticky traps are a highly recommended tool for monitoring adult populations and can help reduce the number of reproductive insects in the immediate vicinity.

Biological control, such as releasing predators like predatory mites (Amblyseius) or minute pirate bugs (Orius), can effectively manage populations without the need for harsh chemicals.

It is essential to rotate different classes of insecticides to prevent the development of resistance, applying treatments at 7–10 day intervals until the population is suppressed.