Fairy shrimp (Chirocephalidae)

Crops affected: The primary target of these pests is rice (Oryza sativa). The most vulnerable stages are seed germination and the early seedling phase. During these stages, the plant relies on stable conditions in the submerged soil, which can be severely disrupted by the biological activity of these crustaceans.

Biology and lifecycle: The lifecycle of Chirocephalidae is adapted to temporary water bodies. They produce dormant cysts that can remain viable in the soil for years during dry periods. Upon flooding the rice fields, these cysts hatch within a few days. The population growth is rapid due to high fecundity and fast maturation, often leading to massive infestations within a short period of irrigation.

Nature of damage and economic importance: The damage is primarily caused by the mechanical disturbance of the substrate and the root system. As the shrimp forage, they stir up the sediment, increasing water turbidity and blocking light necessary for photosynthesis in young rice plants. Furthermore, direct damage to the delicate root hairs leads to nutrient uptake impairment, resulting in stunted growth and significant gaps in crop stands.

Control measures: Management of fairy shrimp populations involves both cultural and chemical interventions. Drainage of the fields for a short period is the most common mechanical method to kill larvae. Chemical control involves the use of selective insecticides or molluscicides registered for use in rice cultivation. Proper field preparation, including precise leveling to avoid stagnant deep spots, significantly reduces the infestation potential.