Planorbarius metidjensis

Systematic position: Planorbarius metidjensis is a species belonging to the order Basommatophora and the family Planorbidae. These freshwater snails are typically associated with aquatic environments but can become a nuisance in agricultural settings, particularly in irrigated areas where they move through water canals into croplands.

Target crops and damage: The pest primarily threatens moisture-dependent crops such as rice and various vegetable varieties grown in wetlands or irrigated fields. The snail feeds on the epidermis and soft tissues of leaves and stems, leading to severe defoliation and weakening of young plants, which stunts their overall development.

Biology and life cycle: As a hermaphroditic species, Planorbarius metidjensis exhibits high reproductive potential. It lays eggs in gelatinous masses on aquatic vegetation or submerged debris. The life cycle is highly adaptive, allowing the snail to survive in muddy substrates during short periods of drought, ensuring rapid population recovery when water returns.

Nature of damage: Damage is characterized by scraping marks and irregular holes in foliage. By destroying the plant's surface tissues, the snail significantly increases the risk of secondary infections by bacteria and fungi, which can lead to rapid decay of the foliage and significantly reduce yield quality.

Protection measures: Integrated pest management is crucial, starting with the maintenance of irrigation ditches and seasonal drainage to disrupt the life cycle of the snail. Mechanical barriers can be used to prevent movement, while molluscicides containing metaldehyde may be employed in severe infestations, provided they comply with local environmental regulations regarding water safety.