Nematodes as important source for omega-3 long-chain fatty acids in the soil food web and the impact in nutrition for higher trophic levels

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Several soil invertebrates, especially nematodes but also collembola and predatory mites, were assigned as a source of long-chain polyunsaturated fatty acids of the omega-3 family (ω3 LC-PUFAs). These are well recognized compounds of great physiological importance in animals, and commonly are regarded as not widely available in terrestrial food webs. Our studies showed that the fitness of Collembola and mites significantly benefited from ω3 LC-PUFA rich nematode diet, resulting in increased biomass and reproduction. This suggest that the biosynthesis of ω3 LC PUFA is costly and uptake by food is profitable for consumers, despite capability for de novo synthesis. Interestingly, co-existence in the same habitat occurs between taxa that can de novo synthesize ω3 LC-PUFAs with closely related taxa that cannot.The new project now asks - what are the physiological and ecological advantages of this de novo synthesis? It further aims to close knowledge gaps in the required enzymatic mechanisms. To achieve these goals, we will combine biochemical (enzymatic activity of fatty acid desaturases) and physiological (stress resistance, competition strength and learning behavior) approaches to gain deeper understanding in the importance of a food independent supply with ω3 LC-PUFA. The results will be completed by empirical data from a field survey comparing the genetic prerequisites to de novo synthesize ω3 LC-PUFA with life strategy of the corresponding nematode species collected in different soil habitats. Thereby, the proposed project will prove the role of ω3 LC-PUFA as an important driving force for interactions in the soil food web.