Figure-eight diving beetle

Systematic position: Suphrodytes figuratus belongs to the order Coleoptera and the family Dytiscidae. This small predatory water beetle is found in various freshwater habitats. While often considered a minor component of biodiversity, it is recognized as a pest within controlled aquaculture environments.

Nature of damage and harm: The main economic impact is observed in fish farming, particularly during the larval and fry stages of fish development. Both the adult beetles and their larvae are predatory, attacking and injuring young fish. This leads to increased mortality rates and reduced yield in commercial nursery ponds.

Biology and life cycle: The life cycle comprises four distinct stages: egg, larva, pupa, and adult. Females deposit eggs on submerged vegetation. Larvae are highly aggressive and equipped with sickle-shaped mandibles for hunting. Adults are proficient fliers, which enables rapid colonization of new water bodies and complicates localized control efforts.

Affected areas and hosts: The species primarily affects fish farms, hatcheries, and managed ponds. In intensive aquaculture, high beetle populations can disrupt the balance of the ecosystem, causing significant losses when high-density fry are stocked without proper management of predatory insects.

Protection measures: Management relies on integrated pond maintenance. Essential strategies include systematic cleaning and drying of ponds, which eliminates breeding grounds for larvae. Furthermore, the installation of mechanical barriers, such as fine-mesh screens, prevents adult migration into sensitive nursery areas, protecting the fry from predatory attacks.