Rice water weevil

Systematic position. Lissorhoptrus bosqui belongs to the order Coleoptera and the family Curculionidae. It is a highly specialized insect pest that primarily targets rice cultivation, representing a significant challenge for agricultural productivity in its habitat range.

Crops and damage. The primary host is rice (Oryza sativa). The larvae are the most destructive stage, feeding on the root system of submerged plants. This damage prevents the crop from absorbing nutrients, leading to stunted growth. Adults, on the other hand, feed on the leaf blades, creating narrow, longitudinal scars that reduce the overall photosynthetic capacity of the rice plants.

Biology and life cycle. This species is perfectly adapted to aquatic environments. Females deposit eggs in the submerged roots or stems of the plants. Upon hatching, the larvae remain underwater, moving through several developmental stages. Before pupation, larvae construct small air-filled cocoons attached to the roots, which allow them to undergo metamorphosis safely while remaining submerged.

Nature of damage. The visual signs of infestation include yellowing foliage and a noticeable reduction in plant vigor. Because the root system is compromised, affected plants struggle to remain upright and often show signs of severe nutrient deficiency. In extreme cases, high larval populations can result in significant stand loss and reduced grain yield.

Protection measures. Integrated Pest Management (IPM) is essential for controlling this beetle. Key strategies include:

• Seed treatment with systemic insecticides before planting.
• Water management, specifically regulating irrigation cycles to interrupt the larval development.
• Application of granular insecticides into the floodwater.
• Crop rotation to reduce the overwintering population in the soil.