Greenhouse Vegetable Sector Biosecurity Guide
Appendix 1: Example of a Thrips Pest Fact Sheet
Thrips Fact Sheet
Pest species include:
Western flower thrips (WFT) – Frankliniella occidentalis
Eastern flower thrips – Frankliniella tritici
Onion thrips – Thrips tabaci
Greenhouse thrips – Heliothrips haemorrhoidalis
Banded greenhouse thrips – Hercinothrips femoralis
Palm thrips – Parthenothrips dracaenae
Cuban laurel thrips – Gynaikothrips ficorum
Eggs are laid in plant tissue. There are two larval stages (Fig. 1) and two non-feeding stages, the pre-pupa and pupa (Fig. 2), and the adult stage (Fig. 3). Larvae feed on the underside of leaves. The second instar larva drops to the soil to form the pre-pupa and then the pupa. Adults emerge to feed on leaf, bud, fruit, and flowers, depending on species. Most species have males and females; however, the onion thrips is parthenogenetic (does not require mating to reproduce). Thrips prefer drier conditions such as along walkways and row ends.
The larvae and adults have "punch-and-suck" mouthparts that pierce the cell wall and remove the cell contents. The thrips will feed on several cells in a patch before moving to another part of the plant (Figure 4). They leave behind particles or oily frass, depending on species. Feeding damage results in cell death. In actively growing tissues, the killed cells result in deformed growth patterns in leaves, flowers and fruit.
Larvae: Examine the undersurface of leaves.
Adults: Examine the underside of leaves, flowers (Figure 5) and fruit, "tapping" a plant over a white sheet of paper, yellow or blue sticky cards in or just above the plant canopy, or trap plants.
Thrips are very difficult to manage and require constant attention.
Prevention: Quarantine and inspect incoming plant material, dip cuttings with an entomopathogenic fungus where permitted by the label, and pre-emptively release biological control agents.
Reaction: Routinely monitor to determine the number of thrips in the crop so that pesticide sprays can be conducted if the population exceeds the economic threshold or to determine if biological control agents or the pesticide applications have been effective. Trap plants such as yellow marigolds can actively draw thrips out of the crop. Sticky tape can be strung throughout the crop to capture flying adults. Overhead irrigation or water sprays can be used to dislodge thrips from plants.
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