Beyond Insects: Emerging Arthropod Reservoirs of Current and Novel Entomopathogens for Insect Pest Management – A Review

With the increasing resistance of insects to chemical pesticides, regulatory pressure on chemical pesticides, and the need for environmentally friendly and benign pest management systems, efforts are geared towards the search for new entomopathogens. Traditional bioprospecting focuses on diseased insects in sourcing for microbes to be used in formulating biopesticides, yet a wide range of non‑insect arthropods—copepods, arachnids (spiders and mites), myriapods (millipedes, centipedes), and other arthropod lineages—harbour microbial pathogens (fungi, oomycetes, microsporidia, bacteria, and viruses) with potentials to control insect pests. This manuscript reviews the ecological rationales, discovery methods, promising taxa, safety considerations, and the processes for sourcing novel entomopathogens from alternative arthropod reservoirs other than insects. We gave evidence that spider‑pathogenic fungi (e.g., Gibellula spp.), entomophthoralean fungi associated with springtails and mites (e.g., Pandora, Conidiobolus), oomycetes found on arthropods in aquatic environment (e.g., Lagenidium, Leptolegnia), as well as microsporidia linked with aquatic crustaceans (copepods) all represent yet-to-be-fully explored resources for both crop and veterinary pest management. We outline an integrated discovery framework which combines high‑throughput field sampling, specialized culture strategies, functional screening in Galleria mellonella and target pests, multi‑omics (amplicon, shotgun metagenomics, metabolomics), and genome mining for virulence/secondary metabolite clusters. Finally, we highlight a regulatory and formulation roadmap to de‑risk development while safeguarding non‑targets and aquatic ecosystems.