Variability in the colonisation of protected vegetable crops by native beneficial insects: the role of crop management and the surrounding landscape

Pest control through natural enemies is an alternative strategy for crop protection in organic market gardening systems. In the Mediterranean region, native mirid bugs (Heteroptera: Miridae) spontaneously colonise protected crops and can play an important role in pest control. However, this control process remains highly variable from one plot to another and is unreliable. This study is being carried out as part of the REGABRI project, which aims to identify the factors influencing the colonisation of tomato crops in organic and conventional farming by mirid bugs in the Roussillon region. An initial survey in 2010–2011 of 34 tomato crops showed that the abundance of mirid bugs within the polytunnels varies according to cropping practices and the characteristics of the surrounding landscape (100m to 200m). A second monitoring study in 2012 identified both cultivated and uncultivated elements in the vicinity of the polytunnels that are likely to either promote (source habitats) or reduce (dilution and sink effects) the colonisation of crops by mirid bugs. These results show that a systemic approach, taking into account the scales of the plot, the cropping system and the landscape, is necessary to optimise natural pest control in protected vegetable farming.