Deciphering the Survival Strategies of the Entomopathogenic Nematode Steinernema carpocapsae Using Rapid Desiccation Assisted by Nanoparticle-Based Emulsion

Water is essential for organisms’ survival. Entomopathogenic nematodes (EPNs), such as Steinernema carpocapsae , experience rapid desiccation (RD) upon application to foliar surfaces, significantly reducing their biocontrol efficacy. Protective strategies employed by the rapidly desiccating EPNs, and their potential improvement through formulations, have been largely unexplored. We determined the protective physiological and molecular mechanisms employed by S. carpocapsae in non-formulated (control) and formulated treatments to withstand RD under different humidity levels. Building on previous results, we hypothesized that titania Pickering emulsion (TPE) and silica Pickering emulsion gel (SPEG) will enhance EPN survival and efficacy through distinct changes in physiological and molecular mechanisms. We determined the effect of RD using gravimetric analysis, confocal microscopy, transcriptomics, ultra-high performance liquid chromatography and ultrastructural (scanning and transmission electron microscopy) assessments. Our results indicate that SPEG and TPE temper the impact of RD in EPNs through diverse physiological mechanisms. Formulated EPNs exhibited significantly delayed water loss and enhanced survival under low humidity compared to controls. Confocal microscopy indicated two distinct protective mechanisms: the primary mode of action in SPEG was retention of hydration on the nematode, whereas TPE effectively slowed water loss from the nematode body. These protective mechanisms correlated strongly with differential patterns of trehalose accumulation, providing biochemical confirmation of formulation efficacy. Transcriptome analysis and ultrastructural validation highlighted the adaptive mechanisms such as—extracellular matrix remodeling, including basement membrane integrity and cytoskeletal reorganization—as critical components of EPN’s adaptative response to RD.