Banker plants and landscape composition influence colonisation precocity of tomato greenhouses by mirid predators

Conservation biological control involves manipulation of the environment to enhance the efectiveness of natural enemies in controlling crop pests. In this study, we combined historical data, sticky trap sampling of tomato greenhouses and beat sampling of adjacent vegetation to identify which greenhouse characteristics, habitat management practices and landscape features favour an early colonisation of tomato greenhouses by the key mirid predator Macrolophus pygmaeus and its establishment in NE Spain. Results show that landscape composition and the use of Calendula ofcinalis banker plants inside the greenhouse are key factors. In general, greater amounts of herbaceous semi-natural cover at the landscape scale promoted M. pygmaeus colonisation, while the use of C. ofcinalis banker plants encouraged M. pygmaeus colonisation independently of the landscape context. We identifed host plants adjacent to tomato greenhouses that sustain M. pygmaeus populations; however, they did not have a major efect on M. pygmaeus colonisation compared to larger landscape and banker plant efects. Early colonisation of greenhouses by this predator species also translated into lower accumulated incidence of pests at the end of the sampling period. This study demonstrates the importance of active habitat management practices in promoting the early arrival of M. pygmaeus in greenhouses with delayed spontaneous colonisation.

This study was funded by EU-funded projects, EUCLID (Project Number: 633999-2) and EMPHASIS (Project Number: 634179-2), the project AGL2016-77373-C2-1-R (Spanish Ministry of Economy and Competitiveness) and the CERCA Programme of the Generalitat de Catalunya. AA was partly supported by a Ramón Areces fellowship while writing this manuscript.