In agroecosystems, increasing plant diversity is known to contribute to numerous ecological services, including regulation of insect pest densities directly or indirectly through the activity of their natural enemies. The objective of this review is to provide an overview and synthesis of the effects of crop diversification methods on insect pest management that can lead to more sustainable vegetable production systems. Focus is on trap cropping, flowering plants, living mulches and intercropping. This review highlights some of the most promising methods (e.g., trap crops supplemented with insecticide application or integrated with biological control, flowering plants that can support omnivorous predators, specific plantings that can act as a ‘virus-sink’) that can be readily implemented by farmers in support of ecologically-based pest management. Advantages and disadvantages associated with trap cropping are discussed in light of its effectiveness, simplicity, and cost considerations in various vegetable systems. Farmscape plants are reviewed in terms of their effects on fitness of parasitoids and omnivorous predators of insect pests, measures of success, and impact of natural enemies as biological control agents. The main mechanisms underlying the effects of living mulches and intercrops on pest suppression are discussed in terms of disruption of host-plant finding and chemically-based repellency, their effects on insect pests and their natural enemies, and potential competition between the cash crop and the neighboring non-crop. While each of these techniques can be a stand-alone approach to pest management, it is advisable to integrate approaches including chemical (if needed – e.g., in the case of trap cropping), cultural, and biological controls. Further development of such methods that promote biodiversity and provide favorable conditions for agriculture based on ecological principles are expected to reduce chemical inputs (e.g., insecticides), thus impacting positively the society and the environment to move towards sustainability in vegetable production systems.
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