Insect pest management in organic agriculture: acting in harmony with complexity
Organic agricultural systems are characterized by a large biodiversity and high complexity. Biodiversity is often associated with a wide variety of entomophagous insects, which allows better natural insect pest control than in conventional systems. This contribution is not only limited to the farm itself. Studies at the landscape level have shown that non-cultivated areas may act as reservoirs for beneficial insects such as predators and parasitoids. However, biodiversity is not always effective at maintaining pests below the economic threshold. Consequently, prevention is a key component in insect pest management in organic crops. Prevention will aim to make the environment favourable to natural enemies but unfavourable to insect pests. Agricultural practices, such as crop rotation and choice of cultivars, are key elements when an integrated pest management approach is applied to an organic system. Along with agricultural practices and precautionary measures, some tools such as row covers, biopesticides and beneficial insects are also available as a last resort. However, the challenge is still overwhelming. Organic agroecosystems are complex and require much more research to understand the mechanisms that will allow natural control to become more efficient.