Greenhouse thrips

Systematic position. The greenhouse thrips (Parthenothrips dracaenae) belongs to the order Thysanoptera and the family Thripidae. This insect is a significant pest of indoor and ornamental plants, particularly common in glasshouses, conservatories, and interior landscaping, where it thrives due to constant temperature and humidity levels.

Host plants. The pest is polyphagous and infests a wide range of tropical and subtropical ornamental species. Common hosts include dracaenas, ficus species, palms, anthuriums, and hibiscus. Greenhouse thrips are particularly attracted to plants with thick, waxy leaves, where they establish colonies on the lower leaf surface.

Biology and life cycle. The life cycle involves egg, larval, prepupal, pupal, and adult stages. Parthenogenesis is the primary mode of reproduction in this species, meaning females produce viable eggs without mating. Under favourable indoor conditions with temperatures between 20°C and 25°C, the lifecycle is accelerated, allowing multiple generations to occur throughout the year.

Damage and pest status. Both adults and larvae feed by piercing the leaf surface and extracting sap. This feeding activity results in chlorotic, silvery patches on the upper leaf surface and the presence of dark, crusty fecal spots on the underside. Heavy infestations cause premature leaf yellowing, desiccation, and severe reduction in the ornamental value of the plant.

Control measures. Integrated pest management (IPM) is crucial for controlling this insect. Strategies include:

• Using yellow sticky traps for population monitoring.
• Removing and destroying heavily infested plant foliage.
• Applying systemic insecticides, such as neonicotinoids, via foliage spray or soil drench.
• Ensuring proper spacing and airflow between plants to reduce humidity hotspots.