Entomopathogenic and plant pathogenic nematodes as opposing forces in agriculture

Abstract

Plant-parasitic nematodes (PPN) are responsible for substantial damages within the agriculture industry every year, which is a challenge that has thus far gone largely unimpeded. Chemical nematicides have been employed with varying degrees of success, but their implementation can be cumbersome, and furthermore they could potentially be neutralizing an otherwise positive effect from the entomopathogenic nematodes (EPN) that coexist with PPNs in soil environments and provide protection for plants against insect pests. Recent research has explored the potential of employing EPNs to protect plants from PPNs, while providing their standard degree of protection against insects. The interactions involved are highly complex, due to both the three-organism system and the assortment of variables present in a soil environment, but a strong collection of evidence has accumulated regarding the suppressive capacity of certain EPNs and their mutualistic bacteria, in the context of limiting the infectivity of PPNs. Specific factors produced by certain EPN complexes during the process of insect infection appear to have a selectively nematicidal, or at least repellant, effect on PPNs. Using this information, an opportunity has formed to adapt this relationship to large-scale, field conditions and potentially relieve the agricultural industry of one of its most substantial burdens.

Effect of the entomopathogenic nematode-bacterial symbiont complex on Meloidogyne hapla and Nacobbus aberrans in short-term greenhouse trials

“…Some EPN isolates may be more effective against certain plant-parasitic nematode species, and some plant species may not be as attuned to the benefits of specific EPNs (Kenney and Eleftherianos, 2016). For this reason, it is important to consider new EPN isolates and compare the effect of different inoculation options of the nematode-bacterial symbiont complex.…”

The symbiotic bacteria Alcaligenes faecalis of the entomopathogenic nematodes Oscheius spp. exhibit potential biocontrol of plant‐ and entomopathogenic fungi

“…() found that EPNs could extend their ecological niche breadth by associating with different symbiotic bacteria. Therefore, the spectrum of ecological consequences that are mediated by EPB extends from influencing the surrounding soil biota to modifying the behaviour of the symbiotic nematodes (Kenney and Eleftherianos, ), which should cascade down to influence the whole soil community dynamics of interactions.…”

Transmission Success of Entomopathogenic Nematodes Used in Pest Control

“…Such multiple infections, although leading to competition between nematodes (see below), lower the risk of them being overcome by the host’s immune system. However, Kenney and Eleftherianos suggested that the success of infection of EPNs used in biocontrol programs could be improved by developing nematode-bacteria complexes that produce proteins necessary for evasion of the host’s immune system, or nematodes with a short delay in the ejection of their bacterial symbionts [ 157 ].…”

“…Because of their negative interaction on other nematodes, EPNs can be used to control pest species. Many studies already documented the efficacy of EPNs against pest nematodes (reviewed by Kenney and Eleftherianos [ 157 ]). For instance, several species of EPNs, and particularly their bacteria, proved to be efficient against the root-knot nematode Meloidogyne incognita , a parasite of tomato plants [ 179 , 180 , 181 ].…”