Enhancing ultraviolet radiation resilience in entomopathogenic nematodes: A systematic review of strain selection, tolerance assessment, and protective formulations

Entomopathogenic nematodes (EPNs) are widely used biological control agents against insect pests in various agroecosystems. However, their effectiveness in the field is often constrained by environmental stressors such as ultraviolet (UV) radiation, extreme temperatures, desiccation, and exposure to agrochemicals. Among these, UV radiation and desiccation on exposed plant surfaces (e.g., leaves, stems, soil surface) are especially detrimental to EPN survival and infectivity. While EPNs, such as Steinernema and Heterorhabditis species, vary in their tolerance to these stresses, current data indicate significant inter- and intra-species variability, possibly linked to strain-level adaptations. Studies assessing EPN resilience typically focus on mortality or infectivity after short-term exposure; however, there is no standard methodology across studies, which limits direct comparisons. This kitchenham systematic review compiles available evidence through network analysis, research gap analysis, and trend analysis on EPN environmental tolerance and outlines formulation strategies such as polymer matrices, UV protectants, and humidity-retaining gels that may enhance persistence. Despite promising lab-based improvements, field results are often inconsistent, underscoring the need for standardized exposure protocols and a deeper understanding of EPN interactions with microclimates and substrates. By identifying robust strains and refining application techniques, this paper aims to support more reliable deployment of EPNs under varying field conditions.