Genotypically diverse cultivar mixtures for insect pest management and increased crop yields.
Abstract
In modern crop production, each plant is often nearly genetically identical to its neighbours, allowing insect pests and pathogens to move easily from plant to plant and decimate crop fields. The associational resistance and enemies hypotheses predict that increasing plant diversity in agricultural fields will reduce pest abundance and damage. Ample research has supported these hypotheses by demonstrating that increased plant species diversity can improve insect pest management via bottom-up and top-down mechanisms. In spite of this support, diversification strategies that might contribute to improved pest control and yield have not been widely adopted owing to logistical and financial constraints. Basic and applied research is increasingly demonstrating the value of intraspecific genetic diversity for improving ecosystem stability and function. Thus, a more practical way of diversifying crop fields may be to increase plant genotypic diversity by planting cultivar mixtures. Our objective is to review the literature documenting the benefits of genotypic diversity for natural and agricultural ecosystems and synthesize the evidence in support of intraspecific diversity as a viable pest management strategy for insect pests of field crops. We found strong support for wide-ranging benefits of genotypic diversity that improved plant fitness and productivity in natural and applied settings. Multiple lines of evidence converge to support the potential of intraspecific variation to contribute to improve insect pest control. However, very little work has sought to develop empirical support or viable implementation practices in agricultural systems. Thus, implementation of this practice is limited. Synthesis and applications. Intraspecific plant diversity can improve plant fitness via bottom-up and top-down effects on pest populations and niche partitioning. Further research is required to refine implementation practices and demonstrate value in terms of reduced pesticide use and increased yield. Growers can implement intraspecific crop diversity with minimal financial investment or changes in production practices. As the benefits of biodiversity for yield stability are increasingly recognized, intraspecific diversity is poised to become a prominent and sustainable management tactic.