Straw itch mite

Taxonomic classification. The straw itch mite (Pyemotes dryas) belongs to the order Trombidiformes and the family Pyemotidae. It is a microscopic, highly adaptive ectoparasite that occupies both agricultural fields and storage facilities, playing a complex role in the ecosystem.

Host plants and damage. This mite primarily affects various grain, legume, and oilseed crops. While it often preys on insect larvae in the field, it causes severe economic losses in storage by feeding on the embryos of seeds. Such damage results in a significant reduction in germination rates and can render harvested grain unsuitable for sowing.

Biology and life cycle. The life cycle of Pyemotes dryas is characterized by viviparity and physogastry. Fertilized females become sessile and their abdomens enlarge significantly to host the developing offspring. The mites complete their entire development cycle inside the mother's body, and the emerging individuals are immediately ready for mating and searching for new hosts.

Symptoms of infestation. In storage, the infestation is often identified by the lack of seed viability and, in severe cases, by reports of skin irritation among workers handling infested materials. In the field, their impact is less direct; however, they can affect plant development by influencing the populations of insects they parasitize or by damaging tissues when their primary insect hosts are scarce.

Control measures. Protecting crops and stored products requires a strict sanitation strategy. Management practices include:

• Maintaining low grain moisture to inhibit mite reproduction.
• Regular cleaning and fumigation of storage facilities.
• Using selective acaricides when population thresholds are exceeded.
• Implementing Integrated Pest Management (IPM) to encourage natural predators.