Bulb mite

The bulb mite (Michaelopus macfarlanei) is a microscopic pest belonging to the Acaridae family, known for causing significant damage to various bulbous plants.

Adult mites are approximately 0.5 to 1 mm in length, possess an oval-shaped, whitish-yellow body with brown legs, and are covered with fine, long bristles.

These mites thrive in high humidity conditions (above 70%) and moderate temperatures ranging from 20 to 25 degrees Celsius, making greenhouse and storage environments ideal.

The life cycle includes egg, larva, protonymph, deutonymph, and adult stages, with the deutonymph stage acting as a highly resistant phase that can survive poor conditions.

Due to their photophobic nature, they remain hidden inside the bulbs, often making early detection difficult until significant damage has already occurred.

Bulb mites attack a wide variety of plants, including onions, garlic, tulips, lilies, daffodils, and other ornamental species grown for bulbs.

The pest penetrates the bulb through the basal plate or existing mechanical wounds, then begins to burrow through the fleshy scales of the plant.

Feeding damage prevents nutrient uptake, leading to root rot, weakened growth, and eventually the death of the entire plant structure.

During storage, the mite causes rapid deterioration of bulbs, turning them into soft, decaying matter covered in fungal spores and mite excrement.

Severe infestations can result in total crop failure, impacting both commercial onion production and the quality of ornamental gardening supplies.

Initial signs of infestation include yellowing and wilting of leaves, which often fail to develop properly and may wither from the tips downward.

In affected ornamental plants, flower stalks may become deformed or fail to bloom, resulting in significant aesthetic damage to the garden.

Upon examination, the basal plate of the bulb appears decayed and brittle, often emitting a distinct, foul odor caused by secondary bacterial decay.

In storage, a layer of greyish dust, consisting of mites and their debris, is often visible at the base of the bulbs or in the storage bins.

• Stunted plant growth.
• Premature wilting of leaves.
• Basal plate rotting.
• Presence of grey dust inside the bulbs.

Effective management begins with proper storage conditions, specifically maintaining low humidity and cool temperatures to limit mite reproduction.

Curing bulbs thoroughly after harvest in warm (30-35 degrees Celsius) and dry conditions is an essential step to reduce the initial mite population.

Chemical control through the application of specific acaricides to the planting material before storage or sowing can effectively manage infestations.

Practicing crop rotation is vital; avoid planting bulbous crops in the same area for at least three to four years to break the mite life cycle.

Sanitation practices, including the removal and destruction of all infested plant material and debris after harvest, are critical to prevent future outbreaks.