Pests| Thrips | Pests main menu |
Due to their excellent natural adaptation thrips have developed to be
one of the most feared and widespread pests. They cause serious damage
to vegetable crops as well as ornamentals and soft fruit.
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Adult thrips are small, elongated insects with typical fringed wings. They measure about 1 mm, and have a greyish or yellow to brown colour. The two most common harmful species are the onion thrips (Thrips tabaci) and the western flower thrips (Frankliniella occidentalis). The female thrips deposits eggs in the leaf tissue. The eggs hatch within a few days into very mobile larvae which immediately start to feed. After the second instar they let themselves fall on the ground to pupate. The total development time from egg to adult takes from 20 days at 20°C (68°F) to 12 days at 30°C (86°F). At sufficiently high temperatures one female thrips can produce up to 200 descendants.
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Thrips damage the crop by withdrawing the plant cell fluids. Empty cells are filled with air, causing a silvery appearance, on which dark spots (the excrements) are visible. Moreover, there exist many more damage symptoms depending on the crop. For instance, thrips on very young cucumber fruits give deformed fruits.
In sweet pepper, they cause cosmetic damage on the fruits close to the calyx. In several ornamentals, flower damage through discoloration or deformation occurs. Only a few individual thrips are enough. Moreover, thrips are important vectors of several viruses (e.g. tomato spotted wilt virus, TSWV).
| Amblyseius cucumeris | Amblyseius degenerans | ||||
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| Orius insidiosus | Orius laevigatus | ||||
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| Orius majusculus | |||||
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