A study published in the scientific journal Soil Ecology Letters demonstrates that the mill waste, treated by vermicomposting, can perform a key role in biological pest control in olive cultivation. The research, conducted in Spain, focused on the interaction between the olive tree, the olive moth (Prays oleae) and its main natural predator, the lacewing (Chrysoperla carnea).
Thus, the reuse of agro-industrial by-products of olive oil as organic soil improvers not only contributes to closing the nutrient cycle within the circular economy, but also triggers induced defense responses in plants.
Root microbiome and volatile signals
The treatment of the soil with these vermicomposted residues, the study explains, significantly altered the microbiome of the olive roots, favoring a greater microbial diversity. This microbial modification directly influenced the production of volatile organic compounds that the olive tree emits when attacked by the olive moth. These compounds act as chemical signals that attract the lacewing, proving to be an efficient biological control agent.
Among the most relevant volatiles identified were nonanal, 6-methyl-5-hepten-2-one and acetic acid, whose emission was positively correlated with the soil organic carbon content and with the diversity of beneficial bacteria and fungi in the rhizosphere.
Towards a more sustainable integrated management
The findings reinforce the importance of consider soil ecology as an essential component in plant protection strategies. The interaction between organic amendments, microbiome and plant defense mechanisms enables the development of more sustainable management methods, in which waste is transformed into resources.
The researchers emphasize the need to continue to evaluate the long-term impact of these practices on soil health and the effectiveness of biological control. The combination of organic microbial fertilization and ecological soil management could represent a promising solution to reduce the use of plant protection products in olive groves.
