Thrips

Thrips, also known as fringed aphids or bladderworts, are among the most important pests in the cultivation of ornamental plants, fruit and vegetables under glass. They belong to the order of fringe-winged insects (lat. Thysanoptera). Flower thrips have an elongated body, hair fringes on the wings and are about 1 - 3 mm in size.

Flower thrips have wings but hardly fly actively. They infest both sides of the leaf blade, but more often the underside. Because of their small size, they can hide well in leaf axils, bud scales, and under the sepals and petals of the open flower, making them difficult for insecticides to reach. A typical infestation characteristic is their dark, dot-like fecal clusters.

Life cycle of the thrips

Adult females live an average of 20 days and lay up to 300 eggs in plant tissue during this time. After 4 - 6 days, the larvae hatch, already causing damage through their sucking activity. The first two larval stages on the plant extend over 5 - 8, the two pupal stages in the soil over 3-5 days. Development from egg to adult takes about 2 weeks at 25 °C. In the greenhouse, 12 to 15 generations occur per year.

Damage caused by flower thrips

Damage is caused by both larvae and adults. It is caused by sucking on leaves and flowers. In the process, cells are sucked out and pollen sacs are opened. Color changes and deformations of fruits and flowers occur. Sucked-out epidermal cells fill with air, giving them a silvery, shiny appearance. The main damage is caused by transmission of viruses, specifically the "tomato bronze spotted wilt virus" ("Tomato Spotted Wilt Virus").

Which plants are damaged by thrips?

Especially susceptible in the greenhouse are ornamental plants (chrysanthemums, streptocarpus (turnip), usambara violets, gloxinia) and vegetables (tomatoes, eggplants, cucumbers, peppers) as well as strawberries.
However, thrips also occur on many other plants under glass.
Control flower thrips with beneficial nematodes

Nematodes are tiny, thread-like soil organisms about 0.6mm long. They are natural enemies of the flower thrips. The nematode species Steinernema feltiae, among others, specializes on the flower thrips and can use it for its own feeding and reproduction. The nematodes are supplied alive in a gel. For application, they should be applied exactly according to package directions.

Which stages of thrips can be controlled?

The best effect is achieved against the stages pre-pupa and pupa.

Agents against thrips - for professional users only

nemaflor® contains nematodes of the species Steinernema feltiae for biological control of pre-pupae and pupae of flower thrips. The gel formulation prevents residues of the product from remaining on flowers and vegetables after spraying.

Application period: nemaflor® can be used in the greenhouse all year round.

Correct use of nematode products against thrips

Dissolve nemaflor® in water and apply with a crop protection sprayer or watering trolley. Apply at weekly intervals, with 125,000 - 250,000 nematodes per m², depending on infestation.

Apply in the evening hours to take advantage of the higher humidity for the nematodes. For application via drip irrigation, use the powder product nemaplus®.

nemaflor® should be used as a supplement in thrips control. Ideal is the use together with predatory beneficial insects on the leaf.

More information about pest control in greenhouses