Plant parasitic nematodes associated with vegetable crops in the main agroecological zones of Côte d’Ivoire

Abstract

Vegetable crops in Côte d’Ivoire are attacked by numerous pests, including plant-parasitic nematodes that cause enormous crop losses. A survey was conducted in six agroecological zones (AEZ) to study the plant-parasitic nematodes associated with vegetable crops. 120 soil and root samples of seven plant species belonging to Solanaceae and Cucurbitaceae were collected. These samples were subjected to various laboratory analyses, including extraction, counting, and identifying nematodes. Plant-parasitic nematodes belonging to nine genera have been inventoried: Meloidogyne, Helicotylenchus, Radopholus, Pratylenchus, Hemicycliophora, Rotylenchulus, Hoplolaimus, Xiphinema and Heterodera. Overall, all the populations were abundant in soils (more than 1000 individuals per kilogram) and roots (more than ten individuals per gram). However, segregation between the genera was observed according to the frequency of populations. The genus Meloidogyne was the most frequent and abundant in the whole localities and vegetable crops. Frequencies of 91% and 100% were observed for Meloidogyne in the roots of tomato and the rhizosphere of zucchini. Xiphinema, Hoplolaimus, Heterodera, and Rotylenchulus had very low-frequency values in soils, while the other genera had intermediate frequency values. The Principal Components Analyses based on nematode populations highlighted a strong correlation between the AEZ I and some genera’s abundance, notably Xiphinema 92% correlated in the roots samples. Similarly, a strong correlation was observed between the abundance of some genera and eggplant; notably, Meloidogyne correlated to 83% in the soil samples. This study highlights the importance of plant-parasitic nematodes in Ivorian vegetable crops, hence the need to implement integrated management measures to limit yield losses.