acariens

Acari, also known as acarines, are a highly diverse group of arachnids that includes both mites and ticks. They are classified as a subclass within the class Arachnida and are divided into two major lineages: Acariformes and Parasitiformes. With tens of thousands of described species and many more likely undescribed, acari occupy a wide range of habitats, from soils and leaf litter to freshwater, marine environments, stored products, plants, animals and humans. Sizes range from less than 0.1 millimeter to several millimeters.

Anatomy and life cycle: Most adults have a body divided into a gnathosoma (mouthparts) and an idiosoma (the main body). They possess four pairs of legs as adults; the larval stage typically has three pairs and lacks the second set of legs, with subsequent nymphs developing eight legs. Mouthparts are adapted for piercing-sucking or chewing, depending on the species. Development is usually from egg to larva, then nymphal stages to adult; many species reproduce sexually, while others can reproduce by parthenogenesis.

Ecology and economic importance: Mites and ticks display extreme ecological diversity. Plant-feeding mites, such as spider mites, can be major agricultural pests. Stored-product mites infest grains and dried foods. Many species are free-living in soil or leaf litter, while others are ectoparasites or endoparasites of animals and humans. Ticks (a group within Parasitiformes) are hematophagous and vectors of diseases such as Lyme disease and other tick-borne illnesses.

Notable human and veterinary relevance: Scabies is caused by Sarcoptidae mites (Sarcoptes scabiei) and causes skin disease; Demodex mites inhabit human hair follicles and sebaceous glands. In apiculture, Varroa destructor parasitizes honey bees and can vector viruses. In agriculture, diverse mite pests are targets of integrated pest management and quarantine measures.