Diversity and ecology of plant-parasitic nematode communities in olive in Spain

This work has studied the diversity of plant-parasitic nematodes infecting olive in a wide-region in southern Spain (Andalusia). Our data indicate that there is a high diversity of plant-parasitic nematodes (including root-knot = Meloidogyne spp., root-lesion = Pratylenchus spp., cystforming = Heterodera mediterranea, stubby- root = Trichodorus spp., reniform = Rotylenchulus sp., dagger and needle = Longidorus spp., Xiphinema spp., ring = Criconemoides spp., Ogmo spp., and other migratory ectoparasitic nematodes viz. Amplimerlinius spp., Helicotylenchus spp., Neodolichorhynchus spp., Paratrophurus spp. Paratylenchus spp., Rotylenchus spp., Trophurus sp., Tylenchorhynchus spp.) associated with olive in Southern Spain that can exert different damage to olive roots depending on the olive variety and their abundance. The highest number of species was detected in Xiphinema and Longidorus, with description of eight and seven new species, respectively, apart from several new records for Spain. In addition, seven Meloidogyne species were detected in wi ld and cultivated olive, from which one is being described as a new species. Multivariate analyses allowed determining the agronomic and environmental factors that drive the structure and diversity of plant-parasitic nematodes infecting olive in Southern-Spain, that included: soil physicochemicol factors (texture, pH, sand and doy, and extractable K), climatic variables (mínimum and maximum temperatures) and the olive cultivar. Nematode abundance and diversity indexes (Richness, Shannon, Evenness and plant-parasitic index) were influenced by olive cultivar, and orchard and soil management predices. The plant-parasitic nematode abundance was significantly higher in orchards managed organically compared to those managed conventionally. These findings could be the result of the influence of the herbaceous plants that compase the soil cover, which may affect plant-parasit ic nematodes at the species level.