Great ramshorn snail

Systematic position. The Great ramshorn snail (Planorbarius corneus) belongs to the phylum Mollusca, class Gastropoda, and family Planorbidae. It is a common freshwater air-breathing snail characterized by its large, flat, disk-shaped shell that coils in a single plane.

Affected crops and damage. This pest primarily threatens aquatic nurseries, hydroponic systems, and rice fields. The snails consume young shoots, delicate foliage, and root systems, which results in stunted plant growth, significant reduction in commercial quality, and even the total destruction of young seedlings.

Biology and development. These snails are hermaphrodites with a high reproductive rate. They attach their egg masses, encased in transparent mucus, to the undersides of leaves or solid surfaces. Their ability to tolerate low oxygen levels and diverse water qualities makes them highly resilient, allowing populations to explode within closed irrigation or ornamental systems.

Damage patterns. Damage is typically manifested as irregular holes, scalloped leaf margins, and damaged root tips. In high-density infestations, the snails can strip an entire tank or pond of its vegetation, posing a major challenge for professional aquatic plant growers and nursery managers.

Protection measures. Management strategies include regular manual removal and inspection of all incoming aquatic plants for egg masses. Maintaining optimal water conditions and implementing thorough cleaning protocols are essential. In severe cases, specific molluscicides may be used, although biological control methods such as introducing natural predators are often preferred for sustainable plant protection.