Species Dynamics, Host Associations, and Black Pepper Resistance Assessment of Root-Knot Nematodes in Espírito Santo, Brazil

Root-knot nematodes (Meloidogyne spp.) are a major constraint to black pepper (Piper nigrum L.) in Espírito Santo (ES), Brazil. No state-wide comprehensive surveys have been conducted so far, and the influence of crop rotation and resistance evaluation is not explored. To address these gaps, 253 root samples were randomly collected from plants across four key microregions of ES. Species diversity, mix-population, and distribution were determined using a polyphasic approach that combined esterase isozyme phenotyping with mitochondrial COII and NADH5 sequencing. In addition, the resistance of the main cultivars 'Bragantina BR-124' and 'Kottanadan' was evaluated using the reproduction factor (Rf), while the influence of preceding crops on nematode occurrence was assessed through a Chi-square test of independence (χ²) and correspondence analysis. Meloidogyne spp. were detected in 94% of the samples (240/253), with mixed infections in 26.7% (64/240) of the fields distributed across 16 municipalities using esterase electrophoresis test. Three species were identified: M. arenaria (88/240), M. incognita (80/240), and M. javanica (8/240). Statistical analyses revealed strong associations between preceding crops and nematode occurrence, particularly M. javanica with papaya (Carica papaya) and sugarcane (Saccharum officinarum), and M. incognita with robusta coffee (Coffea canephora). Resistance screening showed that 'Bragantina BR-124' and 'Kottanadan' were immune to M. enterolobii (Rf = 0), resistant to M. paranaensis (Rf < 1), moderately resistant to M. javanica (Rf = 1.09 and 1.56), but highly susceptible to M. arenaria (Rf = 9.19 and 3.48) and M. incognita (Rf = 4.87 and 2.55). These findings establish the first state-wide baseline for Meloidogyne diversity, distribution, and cultivar resistance in black pepper and demonstrate the critical role of land-use history in shaping nematode communities. The exceptionally high incidence of Meloidogyne spp. in ES black pepper fields is likely linked to the use of infected planting material and preceding crops, underscoring the urgent need for certified nematode-free seedlings, nursery monitoring, and breeding programs incorporating resistance from wild Piper accessions to ensure the long-term sustainability of black pepper cultivation.