• 2026-06-17
• Ariyo A. C., Olojugba M.R., Omokungbe O.R, Oladitan T.O
• Volume 8, Issue 1

Abstract

Plant-parasitic nematodes (PPNs) are among the most economically damaging soil-borne constraints to oil palm (Elaeis guineensis Jacq.) production globally, causing substantial root damage, impaired nutrient uptake, and progressive decline in palm vigor. Concurrently, rhizosphere microbial communities played a fundamental role in regulating soil health and mediating plant–nematode interactions, yet these biotic interactions remained poorly characterized in Nigerian oil palm agroecosystems. This study investigated the morphological diversity of nematodes and their interaction with other microbial communities in oil palm rhizosphere soils in Okitipupa, Nigeria. Soil and root samples were collected from nine selected sites across three communities (Ikoya, Ayeka, and Erinje). Nematodes were extracted using a modified Baermann tray method combined with sucrose centrifugal flotation and identified morphologically under light microscopy. Bacteria and fungi were isolated using standard serial dilution and culture-based techniques, while community diversity was quantified using taxa richness (S), Shannon–Wiener diversity index (H′), and Pielou's evenness index (J′). The results revealed six nematode genera, namely Helicotylenchus, Pratylenchus, Tylenchus, Tylenchulus, Aphelenchus, and Hemicyclophora, with Helicotylenchus spp. dominating across all sites. The bacterial community was dominated by Bacillus spp. and Staphylococcus-like bacteria, while Fusarium spp. and Aspergillus flavus-type colonies were the most prevalent fungal taxa. Ayeka exhibited the highest nematode (H′ = 1.49), bacterial (H′ = 2.43), and fungal (H′ = 2.05) diversity, highlighting significant risks for synergistic root disease development in oil palm. The findings provided foundational ecological data for developing integrated soil health and nematode management strategies in oil palm production systems of southwestern Nigeria.