Innovative uses of banker plants (open rearing systems) can boost biological control in greenhouse and open-field horticulture

<ns5:p>Banker plants, also known as open rearing systems, represent a sophisticated form of conservation biological control that facilitates the in-situ rearing of natural enemies for preemptive pest management in horticultural crops. This systematic review synthesizes the scientific literature on the innovative uses of banker plant systems in both protected (greenhouse) and open-field environments. It reveals the well-established efficacy of classic cereal-aphid-parasitoid systems for aphid management in greenhouses, which function by creating a managed tritrophic interaction that leverages apparent competition. Furthermore, it details innovative strategies, such as the use of pollen-providing flowering plants to sustain generalist predators for thrips control, and the development of advanced, multi-functional architectures like combined systems for multi-pest management and “guardian plant systems” that integrate microbial biocontrol agents. A critical challenge identified is the translocation of these systems from controlled greenhouse settings to variable open-field environments, where success is contingent upon complex factors including landscape ecology, natural enemy dispersal, and resilience to environmental fluctuations. The discussion highlights that while technical efficacy is often demonstrated, the primary barriers to wider adoption are the systems’ ecological complexity and the knowledge-intensive management they require, which contrasts with conventional input-based pest control paradigms. While significant research is imperative, particularly concerning food web interactions, long-term ecological impacts, and robust economic analyses, banker plants are a pivotal technology for advancing sustainable, resilient, and productive horticultural systems.</ns5:p>