autoecisiä

Autoecisiä is a Finnish term used in biology to describe organisms whose entire life cycle takes place on a single host species or host lineage, without requiring an alternate host. In English, the equivalent term is autoecious. This concept is used primarily in parasitology, mycology, and plant pathology. Autoecious organisms are contrasted with heteroecious species, which require two or more distinct hosts to complete their development, often alternating between hosts during different life-cycle stages. The distinction helps explain disease cycles and informs control strategies.

In practice, autoecious parasites may complete sexual and asexual reproduction on the same host, sometimes involving different tissues or life stages within the host. In rust fungi, for example, some species historically described as autoecious complete their life cycles on a single plant host, whereas others are heteroecious, requiring alternate hosts. The term is also used for other pathogens and pests, including certain nematodes and arthropods, that do not depend on multiple hosts.

Etymology: from Greek auto- "self" and oikos "house" or "host." In Finnish scientific usage, autoecisiä is the plural form of autoecinen. Understanding whether a species is autoecious affects monitoring and management. Monitoring focuses on the single host, and control can be more targeted, but the potential for rapid spread on that host remains.