Diversity, Abundance and Virus-Vector Relevance of Plant-Parasitic Nematode Genera in Potato Fields of Limpopo Province, South Africa

Abstract

Limpopo Province is one of South Africa’s major potato-producing regions, yet the field-level composition and community structure of plant-parasitic nematodes (PPNs) remain insufficiently documented. This study surveyed 30 potato fields in four districts to determine the occurrence, abundance and district-level patterns of PPN genera and to identify whether any detected genera had recognised plant-virus vector relevance. Composite root-zone soil samples were collected during autumn 2019. Nematodes were extracted from 250 cm3 soil subsamples, and PPNs were identified to genus level. Data included PPN, total nematodes, plant-parasitic percentage (PPP), fungal-feeder, bacterial-feeder, Wasilewska Index and Nematode Channel Ratio values. Ten plant-parasitic genera were detected in 25 of 30 fields (83.3%). Meloidogyne had the greatest mean density and prominence value, while Meloidogyne and Helicotylenchus were the most frequent genera. Waterberg had the highest median PPP and the lowest median WI, indicating dominance of PPN in the sampled fields. A virus-vector assessment showed that Nanidorus was the only detected genus that belongs to a nematode family with recognised tobravirus-vector potential. The findings provide an improved baseline for nematode surveillance in Limpopo potato fields and indicate that future monitoring should combine genus- and species-level nematode diagnostics with virus testing where Nanidorus or other trichodorids are detected.