Chrysanthemum thrips

Thrips nigropilosus, commonly referred to as the chrysanthemum thrips, is a significant pest belonging to the order Thysanoptera and the family Thripidae. It is a highly mobile insect that causes economic damage by feeding on the sap of various host plants worldwide.

This pest primarily attacks members of the Asteraceae family, most notably chrysanthemums and pyrethrum, though it can also infest other vegetables and ornamental crops. It is particularly problematic in greenhouses, where stable temperatures allow the pest to maintain high reproductive rates throughout the year.

The life cycle of Thrips nigropilosus consists of egg, two larval stages, prepupa, pupa, and adult. Eggs are inserted into plant tissues, and development from egg to adult is highly dependent on ambient temperature, often completing within less than three weeks in warm indoor conditions.

The damage is caused by the puncturing of plant cells, which leads to characteristic silvering or bronzing of the foliage. Infested plants show stunted growth, distorted leaf development, and poor quality of floral buds. Excrement left by the thrips often appears as tiny black spots on the leaves, further degrading marketability.

Effective management requires an Integrated Pest Management (IPM) approach:

• Monitoring populations using blue sticky traps.
• Implementing biological control using predatory mites or pirate bugs.
• Sanitation practices, including the removal of crop debris and host weeds.
• Selective use of insecticides, ensuring rotation to prevent resistance development.
• Maintaining greenhouse hygiene to eliminate overwintering sites.