Verdecia Mogena, Arletys María (2025). Entomopathogenic Nematodes-Maize Interactions: Implications for Sustainable Agriculture. (Thesis). Universität Bern, Bern

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Abstract

Natural enemies of herbivores provide a biocontrol tool for insect pest management. Previous studies focused on understanding the interactions between plants, herbivores and herbivore natural enemies. However, the direct interactions between plants and herbivore natural enemies remains underexplored despite their potential relevance for agroecology. This work aimed to provide a better understanding of the interactions between plants and insect natural enemies and the role of bacteria associated with insect natural enemies in these interactions. The model system was maize Zea mays L. and a species of entomopathogenic nematodes (EPNs) Heterorhabditis bacteriophora Poinar. Chapter 1 provides a comprehensive characterization of maize local response to EPN exposure using transcriptomic and metabolomic analyses. The results indicates that maize plants respond locally to the presence of EPNs in the soil inducing a mild stress response that resulted in altered metabolomic and signalling pathways. However, this EPN-induced shift in the maize metabolome does not affect herbivore performance nor survival of Diabrotica spp. larvae. Chapter 2 presents a characterization of systemic maize response to EPN presence in the soil after an observation in the field trial where EPNs reduce aboveground maize plants infestation by the herbivore Ostrinia nubilalis. The chemical cues underlying the insect oviposition preference remain unknown, although preliminary data suggest the involvement of wax or lipid derivatives. Chapter 3 confirms that EPNs carry a rich microbiota other than the well-known symbiont genus Photorhabdus quite conserved across environmental conditions and insect hosts. The findings also suggest that EPN surface bacteria can alter soil bacterial community. Chapter 4 provides a broad description of the effect of members of the core microbiota of EPNs on plants, insects and EPN fitness and survival. The results confirm that some members of the core microbiota of EPNs are involved in EPN entomopathogenicity and influence EPN survival in in vitro conditions. This work highlights the context-dependent nature of plants-EPNs-microbes interactions providing a better understanding of multitrophic interactions. The findings present new aspects for improving the use and the potentiality of EPNs and their associated microbes in sustainable agriculture.

Item Type:	Thesis
Dissertation Type:	Cumulative
Date of Defense:	27 March 2025
Subjects:	500 Science > 570 Life sciences; biology 500 Science > 580 Plants (Botany)
Institute / Center:	08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS)
Depositing User:	Hammer Igor
Date Deposited:	16 May 2025 13:36
Last Modified:	16 May 2025 13:37
URI:	https://boristheses.unibe.ch/id/eprint/6161

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