Antagonistic potential of Moroccan entomopathogenic nematodes against root-knot nematodes, Meloidogyne javanica on tomato under greenhouse conditions

Ali El Aimani,Slimane Khayi,Rachid Mentag,Rachid Lahlali,Fouad Mokrini,Ghizlane Diria,Driss Iraqi,Abdellah Houari,Salah-Eddine Laasli,Abdelfattah A Dababat

doi:10.1038/s41598-022-07039-0

Abstract

The root-knot nematode, Meloidogyne javanica is a devastating pest affecting tomato production worldwide. Entomopathogenic nematodes (EPNs) are considered very promising biocontrol agents that could be used to effectively manage plant-parasitic nematode. The antagonistic activity of five EPN strains isolated from different fields in Morocco was evaluated against juvenile (J2s) antagonism in soil, the number of egg masses, and the galling index of M. javanica and J2s reproduction in the root. In greenhouse experiments, Steinernema feltiae strains (EL45 and SF-MOR9), Steinernema sp. (EL30), and those of Heterorhabditis bacteriophora (HB-MOR7 and EL27) were applied to the soil alongside RKN J2s. There was a significant reduction in M. javanica densities in the soil and roots by EPNs treatments when compared to the positive control. The EPNs decreased both egg masses formation and galling index by 80% compared to the positive control. The application of EPNs at a rate of 50 and 75 infective juveniles (IJs) cm−2 gave significant control of all studied nematological parameters compared to the positive control, which confirmed the importance of the doses applied. The applied dose was significantly correlated with M. javanica parameters according to polynomial regression models. The results also showed that S. feltiae strain (EL45) significantly increased plant height and root length, while H. bacteriophora strain (HB-MOR7) only enhanced root fresh weight. Therefore, both indigenous EPN strains; EL45 and SF-MOR9 have eco-friendly biological potential against M. javanica in vegetable crops.

Highlights

Plant-parasitic nematodes (PPNs) are viewed as major biotic constraints causing great damage and yield loss to the majority of crops worldwide[1,2,3]
H. bacteriophora strains (EL27 and HB-MOR7) demonstrated less antagonistic activity toward J2s densities in the soil and root system when compared to the positive control (Findex = 22.4; df = 1; P < 0.05)
The interaction between PPNs and Entomopathogenic nematodes (EPNs) resulted in distinct antagonistic patterns that could have implications for implementation in vegetable production and attempts to reduce the use of chemical methods

Summary

Introduction

Plant-parasitic nematodes (PPNs) are viewed as major biotic constraints causing great damage and yield loss to the majority of crops worldwide[1,2,3]. Meloidogyne incognita and M. javanica have been reported to be the most common species[8,10] This wide distribution and frequent occurrence of RKNs require effective management strategies to keep their damage under the threshold levels. Entomopathogenic nematodes (EPNs) of the genera Steinernema (Panagrolaimomorpha: Steinernematidae) and Heterorhabditis (Rhabditomorpha: Heterorhabditidae) are potential biocontrol agents that showed efficient antagonistic effects against many insect p ests[11]. These beneficial nematodes invade and kill insects within 24–48 h. The main objective of this study is to investigate the antagonistic activity of native EPN strains against M. javanica under greenhouse conditions in Morocco

Objectives

Methods

Results

Conclusion