Strategies of entomopathogenic nematodes and their symbiotic bacteria against plant parasitic nematodes

Plant parasitic nematodes (PPNs) are microscopic organisms that inhabit soil and plant tissues causing a significant challenge for farmers around the globe leading to substantial crop damage and losses. Major concern on the indiscriminate use of chemical nematicides has led to exploitation of safe alternatives to mitigate these losses. Entomopathogenic nematodes (EPNs) Steinernema spp. and Heterorhabditis spp. and their associated symbiotic bacteria, Xenorhabdus spp. and Photorhabdus spp. have gained attention as eco-friendly biocontrol agents against insect pests and nematodes. They have the ability to kill the insects by causing septicaemia disease in host insect by production of toxins. EPNs are soil inhabiting, free-living nematodes that also combat PPNs. The secondary metabolites produced by these bacteria exhibits antimicrobial, antifungal, nematicidal, insecticidal, and even anticancer properties. This current review explores the potential of EPNs and their symbiotic bacteria as nematode management strategies by targeting different stages of PPNs resulting in decreased egg production and nematode population. The EPNs and their associated bacteria suppress PPNs by three different ways viz., repulsion, competition and antagonism. Overall, EPNs and their symbiotic bacteria offer sustainable and effective alternatives to chemical pesticides, since application of hazardous chemical pesticides are harmful to environment and human health. This review gives an overview and idea for further research and development of EPN's and their symbiotic bacteria as commercial bioproducts towards PPNs control.