Bulb mite

Schwiebea similis is a species of mite belonging to the order Acariformes and the family Acaridae. It is a common soil-dwelling pest that primarily thrives on decaying organic matter but can become a significant problem in agriculture by infesting root vegetables and bulbs, especially when these plant parts have been weakened by mechanical injury or other diseases.

The host range for this pest includes various bulbous plants like onions and garlic, as well as root crops such as carrots, potatoes, and beets. While they are often present in low numbers in healthy soil, they become highly destructive in storage environments where high humidity and moderate temperatures provide ideal conditions for population outbreaks.

The biology of Schwiebea similis is characterized by a rapid life cycle, passing through egg, larval, and nymphal stages before reaching adulthood. A notable aspect of their biology is the formation of a specialized survival stage known as the hypopus, which is highly resistant to environmental stressors, including dehydration and various chemical treatments.

Damage caused by these mites usually starts at the root plate or crown of the plant. They burrow deep into the tissues, causing the plant material to break down and rot. This feeding activity creates pathways for secondary infections, such as bacteria and fungi, which often cause more damage than the mites themselves. Infested bulbs often become hollow, mushy, and completely unfit for consumption or planting.

Integrated pest management (IPM) is essential for controlling this mite. Key strategies include ensuring crops are thoroughly dried before storage to keep humidity levels low and maintaining storage temperatures near freezing. In the field, crop rotation and sanitation are critical, as removing crop residues prevents the buildup of mite populations and limits their ability to survive between growing seasons.