Entomopathogenic Nematodes – Entomopatogenic Fungi interaction in Microbial Control

Entomopathogenic fungi and entomopathogenic nematodes are globally distributed soil organisms capable of infecting and killing a wide variety of insects. Therefore, these organisms are frequently used as biocontrol agents in insect pest management. Both entomopathogenic fungi and nematodes share the soil environment and therefore can infest and compete for the same insect host. However, natural co-infections are found rarely due to the cryptic soil environment. Due to a recent trend of combining biocontrol agents to increase their efficacy, many studies focused on the co-application of different species of EPF and EPNs against various insect pests with variable outcomes for instance, synergistic effect, additive effect, and antagonism. Also, the effect on the development and reproduction of each pathogen varied from normal reproduction to exclusion, and generally, the outcomes of the interactions were dependent on the pathogen and host species, pathogen doses, and timing of infection. The interactions between entomopathogenic fungi and nematodes are very competitive and, in general, the nematodes appear to be stronger competitors due to their faster infestation and development inside the host. Nevertheless, in particular pathogen species and strain combinations, the outcome can be different. The relationship between entomopathogenic fungi and the nematodes is mostly antagonistic, where one or both competitors are negatively affected. Nevertheless, the effect of dual pathogen infection can have an additive or synergistic effect on host mortality and can be used to increase the effectiveness of both pathogens in biological control. In addition, the insects infected with the fungus respire more and attract entomopathogenic nematodes that follow the gradient of carbon dioxide. It is generally accepted that the efficacy of pest control agents can be improved by their combination. Two control agents applied together can act independently of each other in each host, and the impact on the target organism is the sum of the impact of each one resulting in an additive effect. The interaction can be also synergistic or antagonistic, and the combination is thus more or less effective in control than in the case of an additive effect. In synergy, one agent causes the target organism more susceptible to the other; while in antagonistic interaction, the agents are in competition or interfere with each other. Conclusion: good results with entomopathogenic nematodes, good results with entomopathogenic fungi (EPF conidia do not move but nematodes can move): Why do not use EPN & EPF together.