A recent study published in Soil Ecology Letters has elucidated the combined effects of soil amendments and pest attacks on plant-induced defence mechanisms and their impact on the behaviour of biological control agents. The research, conducted by the Spanish National Research Council (CSIC) and Fundación MEDINA, focused on the utilisation of vermicomposted olive mill waste as a soil amendment and its consequence on the tri-trophic interactions between olive trees (Olea europaea), the carpophagous generation of the olive moth (Prays oleae), and its natural predator, the green lacewing (Chrysoperla carnea).
The study emphasizes the pivotal role of belowground ecology in plant defence within a circular economy framework. The findings demonstrate that the application of vermicomposted olive waste and the simulation of Prays oleae attacks have a significant impact on the volatile compounds emitted by olive trees. These alterations in volatile compounds affect the attraction of Chrysoperla carnea, a principal predator of the olive seed-feeding caterpillar.
It is of particular significance that the research illustrates the important contribution of belowground fungal diversity in determining the composition of aboveground plant volatiles. Moreover, this study indicates that the attractiveness of these aerial volatiles is linked to soil organic carbon content and the diversity of both bacterial and fungal root communities. It is notable that three specific volatile compounds – 6-methyl-5-hepten-2-one, acetic acid and nonanal – were found to consistently attract the lacewing Chrysoperla carnea.
These findings emphasise the necessity of continuous monitoring of soil amendments in order to comprehend their influence on plant-induced defence mechanisms and their potential to enhance biological control strategies. The study offers valuable insights that can inform sustainable agricultural practices and the effective reuse of organic waste as soil fertilisers.
DOI: 10.1007/s42832-024-0281-z