New Zealand flatworm

Systematic position: Arthurdendyus triangulatus belongs to the phylum Platyhelminthes, class Turbellaria, and family Geoplanidae. Originating from New Zealand, it has become an invasive threat in various parts of the world, primarily affecting temperate climates where humidity levels are high.

Biology and life cycle: These creatures are hermaphrodites that can produce egg cocoons throughout the year under suitable moist conditions. The egg cocoons appear as small, shiny black capsules, roughly the size of a pea. Once hatched, the juveniles resemble adults and begin their predatory behavior almost immediately, growing steadily in cool, damp environments.

Crops affected: The species does not attack plant tissues directly but causes widespread damage to agricultural and horticultural land by eliminating earthworms. Since earthworms are vital for soil health, their disappearance affects virtually all types of crops, including vegetables, fruit trees, and ornamental plants that rely on healthy soil structure.

Character of damage and harmfulness: The flatworm hunts by trailing the mucus left by earthworms. Once caught, it wraps its body around the prey and secretes enzymes to digest the earthworm externally. A high population density of these flatworms can lead to a total collapse of earthworm populations, causing soil compaction and a significant drop in organic matter decomposition.

Protection measures: Controlling this pest is challenging as there are no chemical pesticides currently approved for its eradication. The following integrated management practices are recommended:

• Quarantine measures: inspect all incoming plants and soil thoroughly.
• Manual removal: collect flatworms by hand (wearing gloves) and destroy them in salt water.
• Habitat modification: clear debris and stones where the flatworms prefer to hide.
• Monitoring: use non-porous mats to trap and collect specimens during damp weather.