Attributes of natural enemies in ephemeral crop habitats

Ephemeral habitats differ from perennial habitats by their temporal and spatial continuity. The ephemeral habitats that compose annual crops impose constraints on the herbivorous pests and their natural enemies that exploit such habitats. Biological control theory that is based largely on the experiences and successes associated with perennial habitats may not align with opportunities that exist in ephemeral crop habitats. Traits of natural enemies that are successful in ephemeral habitats may not be the same as those associated with natural enemies that are successful in perennial habitats. We suggest that the practice of biological control in ephemeral crop habitats may require a different perspective that recognizes the duration of habitat structure and that desired traits of natural enemies might differ, depending on the particular biological control objective. (C) 1997 Academic Press.