Acarus immobilis

Systematic position. Acarus immobilis belongs to the order Acariformes and the family Acaridae. It is a microscopic arachnid known primarily as a stored-product pest. These mites are ubiquitous in storage environments where high humidity and temperature permit the rapid expansion of their populations.

Affected crops. The pest targets a wide range of stored agricultural commodities, including cereals, oilseeds, legumes, and processed products like flour. It is particularly prevalent in silos and warehouses where grain moisture content is not strictly managed, leading to rapid contamination of the bulk.

Biology and life cycle. The development cycle of Acarus immobilis includes eggs, larvae, protonymphs, deutonymphs, and adults. Under favorable conditions, the mite reproduces exponentially. A critical aspect of its biology is the formation of a hypopus stage—a non-feeding, highly resistant dispersal stage that allows the mite to survive periods of food scarcity or adverse environmental conditions.

Damage and economic impact. Mites feed primarily on the grain embryo, drastically reducing seed viability. They also consume the endosperm, leading to physical loss of commodity mass. Their presence is linked to the introduction of micro-organisms, causing grain heating, rancidity, and the formation of unpleasant odors, which often leads to the condemnation of the entire grain lot.

Control measures. Mitigation focuses on preventive environmental management. Key strategies include:

• Maintaining grain moisture below 13% to inhibit mite development.
• Regular monitoring of stored grain for hotspots and mite presence.
• Strict sanitation and structural maintenance of storage facilities.
• Application of appropriate fumigants in accordance with agricultural regulations when infestation thresholds are exceeded.