BackgroundBiological control of insects is the current goal of modern researches to avoid using the harmful chemicals. Some fungi are capable of infecting and killing insects and, hence, are commonly known as entomopathogenic fungi (EPF). On the other hand, some insects can kill harmful fungal strains using their products such as peptides. Hence, the aim of this review article is to highlight the use of EPF as biocontrol tools against each other.ResultsEPF are generally characterized by having a wide range of hosts which made them the perfect candidate for biological control missions. They are existing in abundance in the environment and involved in plenty of environmental interactions. They have prestigious enzymatic machinery and toxins that contribute as killing tools. Moreover, after penetrating the insect, the expanded vegetative growth of hyphal bodies enabling the invasion of the fungi throughout the entire tissues of host insect cause physic, histolytic, and pathologic changes ultimately leading to the death of the host insect. On the other hand, some insects can kill harmful fungal strains using their secreted products such as peptides.ConclusionIn this review, the use of fungi and insects as biological control agents against each other was described. Furthermore, the history of using EPF for this purpose, their killing mechanism, host range, and the factors affecting EPF virulence were highlighted. Moreover, the role of insect’s immunology and some insect’s products as antifungal agents was presented focusing on peptides with biological activities against fungi. Finally, future prospects concerning the use of insects and fungi in biological control process were discussed.