Abundance and diversity of plant-parasitic nematodes associated with watermelon in Nigeria, with focus on Meloidogyne spp.

Little information is available for nematode pests associated with watermelon in sub-Saharan Africa (SSA). This study recorded the abundance and prevalence of plant-parasitic nematodes from 25 localities across south-west Nigeria during 2016/2017. Of the 11 nematode species identified, those belonging to Meloidogyne spp. were predominant according to Prominence Values, followed by Helicotylenchus dihystera, Pratylenchus zeae and Scutellonema bradys. Morphological and molecular analyses revealed the identity of four species of root-knot nematodes: Meloidogyne enterolobii, M. incognita, M. javanica and M. arenaria (in descending order of abundance and occurrence). Meloidogyne arenaria is reported for the first time from south-west Nigeria, while S. bradys and Xiphinema nigeriense are first reports for watermelon. Significant associations were observed between the frequency of occurrence of the predominant nematode species and soil properties as well as rainfall. Results provide baseline information on the nematode pest occurrence on watermelon in Nigeria and in a wider context for SSA.