FORMULATION AND APPLICATION TECHNOLOGIES OF ENTOMOPATHOGENIC NEMATODES: FROM TRADITIONAL CARRIERS TO NANOFORMULATIONS

Abstract

Entomopathogenic nematodes (EPNs), primarily belonging to the families Steinernematidae and Heterorhabditidae, are widely recognized as effective and environmentally friendly biological control agents against a wide range of soil-dwelling and, increasingly, foliar insect pests. Although EPNs have a broad host range and can be integrated effectively into integrated pest management (IPM) programmes, their commercial use has been limited by several challenges, particularly the short shelf life of infective juveniles (IJs), their sensitivity to desiccation, and their susceptibility to ultraviolet (UV) radiation. Over the years, formulation technologies have evolved considerably, beginning with simple aqueous suspensions and moisture-retaining carriers such as sponge, vermiculite, peat, and clay. These approaches were subsequently followed by gel-based and alginate encapsulation systems and, later, by partially desiccated formulations such as wettable powders, water-dispersible granules, and wheat-gluten-based Pesta granules. More recent developments include superabsorbent polymer and hydrogel based formulations, which can improve IJ survival under room-temperature storage conditions. Nanotechnology has further expanded the possibilities for EPN delivery, with materials such as titanium dioxide and silica nanoparticles being investigated as protective coatings, including their incorporation into Pickering emulsions to reduce desiccation and UV-related damage during foliar application. In addition, early research has explored the nanoformulation of EPN-derived venom proteins as potential bioactive insecticidal agents. Alongside formulation development, application technologies have also progressed from conventional soil drenches to drip and micro-sprinkler irrigation, adjuvant-assisted foliar sprays, granular broadcasting, infected host or cadaver-based delivery, and more precise encapsulated placement systems. The suitability and effectiveness of these application methods are closely linked to the characteristics of the formulation used. This review also considers the physiological mechanisms associated with desiccation and cold tolerance that influence formulation performance, as well as concerns related to nanoparticle biosafety, regulatory approval, and commercialization. Overall, the development of EPN formulations demonstrates a clear transition from simple carrier-based approaches toward engineered, stress-protective, and nanoscale delivery systems. Future advances in precision application, biodegradable polymers, hydrogels, and nanocarrier technologies may further improve EPN stability, field performance, and commercial viability, helping EPN-based biopesticides become more competitive with conventional insecticides.