Striped whirligig beetle

Systematic position. The striped whirligig beetle (Aulanogyrus striatus) belongs to the order Coleoptera and the family Gyrinidae. These insects are easily recognized by their unique swimming behavior on the water surface and their divided eyes, which allow them to see both above and below the water line simultaneously.

Biology and life cycle. This species undergoes a complete metamorphosis. Adult females lay eggs directly on submerged aquatic vegetation. Larvae are strictly aquatic, possessing specialized abdominal gills for underwater respiration. After completing several larval stages, they leave the water to pupate in cocoons attached to plants near the shoreline.

Affected crops and damage. While not a major global pest, Aulanogyrus striatus can become problematic in flooded agricultural systems, particularly rice paddies. Larvae cause damage by feeding on the submerged parts of young rice plants, including roots and delicate shoots, which disrupts the normal nutrient uptake of the seedlings.

Harmfulness. In areas with high beetle population density, crop thinning becomes a significant issue. The presence of these insects can lead to reduced plant stand uniformity and increased susceptibility to waterborne diseases. Furthermore, high concentrations of larvae can interfere with the nutrient balance in the water column of the paddies.

Control measures. Protecting crops from whirligig beetle infestations requires a strategy focused on environment management:

• Implementing intermittent irrigation practices to dry out paddies and destroy larval habitats.
• Strict control of aquatic weed growth around the edges of fields to reduce oviposition sites.
• Application of selective, water-safe insecticides during peak beetle activity.
• Encouraging natural predators such as frogs, dragonflies, and insectivorous fish to maintain biological balance.