ABSTRACT
On about 1.000 ha of glasshouse vegetables in the Netherlands the main pests are controlled by annual introduction of their natural enemies (Table I). A private company organizes the mass production and delivery of the control agents (the parasitic wasp Encarsia formosa against greenhouse whitefly, and the predatory mite Phytoseiulus persimilis against red spider mite), and offers intensive guidance to the individual grower on à commercial base.
