Development of Sustainable Strategies to Control Plant Parasitic Nematodes by Using Plant Derived Formulations

This PhD thesis is the result of a convention agreement between the CNR, Institute for Sustainable Plant Protection (IPSP), Bari, Italy, and the University of Basilicata, Italy. The main protagonists are Plant-Parasitic Nematodes (PPNs), which are some of the most economically important pathogens of crops worldwide, causing yield losses of over US$157 billion annually. The foundation of this thesis was laid through the morphological and molecular characterisation of some PPNs economically important in crops like grapevine and olives under different management systems. Early detection techniques were developed before the work on developing sustainable solutions for PPNs control using biocidal derivatives (Essential Oils (EOs) and extracts) of plant origin. The main research line is the in-vitro evaluation of plant-derived formulations and their deployment for the control of PPNs, in response to the ban on many synthetic nematicides and the EU Green Deal, which necessitated the search for more sustainable alternatives for crop protection. This thesis evaluated in vitro the biocidal effects of essential oils of sweet wormwood, Artemisia annua, on two PPNs characterized by different parasitism modes: the root-knot nematode, Meloidogyne incognita, and the root-lesion nematode, Pratylenchus penetrans. Furthermore, the effects of A. annua essential oils from different geographical locations (India and Italy) at different incubation times and concentrations to determine the minimum concentration that exhibited nematicidal effects were evaluated. The molecular pathways involved in the response of the nematodes were also studied using RNA and Real-Time PCR techniques. Commercial EO of A. annua from India showed higher effectiveness on M. incognita second-stage infective juveniles (J2s) compared to the laboratory-extracted EO from Italy. The study demonstrated that the different nematicidal effects of the A. annua EOs and different expression profiles of the investigated genes following the treatment of the M. incognita J2s are associated with distinct phytochemical compositions, different geographical origins, and season of collection. These findings, including a clear understanding of the molecular pathways and modes of action, demonstrate that A. annua is a promising EO for the development of effective and eco-friendly nematicides, paving the way for future applications in sustainable management of plant-parasitic nematodes.