Interactions between the European red mite, Panonychus ulmi (Koch), and the predaceous mite Amblyseius potentillae (Garman) were studied under semicontrolled glasshouse conditions in two types of ecosystems: single leaves, isolated by a sticky barrier at the petioles, and eight-leaf seedlings. Three different starting numbers of the prey (one, four, and eight females, respectively) were established in each type of ecosystem, and a single adult female predator was introduced 10 days later. Predator-free controls were also included.
