Compatibility of Entomopathogenic Nematodes with Agrochemicals and Biocontrol Potential of their Combinations against Insect Pests: An Updated Review

Entomopathogenic nematodes (EPNs) are biocontrol agents against various insect pests in the world for their characteristics of infectivity and compatibility with different control agents. Several environmental factors directly affect the EPN populations in the soil, as well as the resistance of certain insect pests to EPN penetration. Under these circumstances, EPNs cannot exhibit high virulence on the targeted insect pest; therefore, they should be applied in combination with some of the other control agents. In this context, the main objective of this review was to summarize the current knowledge on the compatibility of EPNs with various agrochemicals and examine the interactions of EPNs and these agents in combined application against insect pests. This review highlighted firstly the growing research attention worldwide concerning the compatibility of EPNs with other control agents. Then, the compatibility of EPNs with synthetic insecticides of different classes was reviewed. In this regard, also, some special attention has been paid to herbicides, fungicides and nematicidal compounds as possible compatible agents to EPNs. Later on, the current review discussed the importance of EPN application in combination with different insect growth regulators, juvenoids, ecdysteroids and chitin synthesis inhibitors. An overview of agricultural management practices and soil amendments in relation to EPNs was provided including the compatibility of EPNs with organic and inorganic fertilizers. Some attention has been paid to the EPN tolerance and susceptibility to heavy metals and other soil chemical pollutants, and EPNs as good bio-indicators of the environmental pollutants. The last aspect was the compatibility of EPNs with crude plant extracts and isolated phytochemicals. In conclusion, a combination of EPNs with compatible agrochemicals is a promising approach to the pest control strategy. EPNs may be combined with various compatible agrochemicals with additive, or preferably synergistic, effects on pest mortality. For this purpose, also, the exposure period should also be taken into consideration, because the exposure of EPNs to agrochemicals for a prolonged exposure period may turn their interaction to antagonistic and subsequently low control efficiency against the targeted insect due to the reduction of the EPN viability and infectivity.