Bipalium kewense

Systematic position: Bipalium kewense belongs to the phylum Platyhelminthes, class Turbellaria, order Tricladida, and family Geoplanidae. Often referred to as a "hammerhead worm" due to the distinct shape of its cephalic plate, this species is a non-native invasive predator that has spread globally via the international nursery and plant trade.

Biology and life cycle: This worm is a hermaphrodite, primarily reproducing asexually through a process called fragmentation. The posterior part of the body detaches and develops into a new, independent individual. These worms are highly moisture-dependent, strictly nocturnal, and prefer habitats with high humidity and stable temperatures, making greenhouses and gardens their ideal environment.

Nature of damage: Unlike most plant pests, Bipalium kewense does not consume plant tissues directly. Instead, it is an apex predator of the soil, specifically hunting earthworms. By consuming earthworms, which are essential for soil aeration and nutrient cycling, the flatworm disrupts the beneficial biological activity within the substrate, leading to poor soil structure.

Impact on crops: The economic impact is mainly felt in horticultural settings, such as greenhouses, commercial nurseries, and ornamental plant collections. By decimating earthworm populations, the presence of these flatworms can lead to soil compaction and a subsequent decline in plant vigor. While not a direct phytophage, its ecological disruption negatively affects the overall health of greenhouse crops.

Control measures: Effective management of this invasive pest relies on strict biosecurity and cultural practices. Growers should:

• Inspect all incoming soil, compost, and nursery stock for the presence of flatworms.
• Maintain drier surface conditions in greenhouses to discourage their activity.
• Manually remove and dispose of identified worms using salt or alcohol solutions.
• Avoid the movement of potentially infested soil between different greenhouse zones.