Exploring Actinobacteria for new insecticides and their delivery in crop protection

Crop protection is essential for agricultural production systems, safeguarding yields and product quality. Chemical controls are a mainstay of protection; however, regulatory and consumer demands, environmental concerns and a general overreliance resulting in resistance development in pest populations have led to increased interest in biopesticides and environmentally friendly alternatives. Biopesticides targeting insects include micro-organisms and their derivatives, such as peptides and specialized metabolites. Their target specificity, structural complexity, modes of action and environmental safety are key differentiators to chemical controls, and when used in integrated pest management programmes, biopesticides can reduce reliance on chemical pesticides and promote sustainable agriculture. As the demand for bioinsecticides grows, so too has the research and application of micro-organisms, alongside their taxonomic diversity and isolation sources. Of key interest are Actinobacteria as both promising and well-tested alternatives for managing insect pests in various agricultural settings, with several products commercialized for use across a variety of crops and target pests. Recent advances and investigations in metabolomics and genomics highlight the untapped and significant biochemical potential and value of Actinobacteria for natural product discovery. This review covers a broad spectrum of published literature that has reported on insecticidal biological activity data associated with Actinobacteria or their natural products. We also report on Actinobacteria-derived nematicides and acaricides that are significant for crop protection. The origin of these natural products, their structural diversity and notable substructures are discussed, along with new areas for discovery and avenues for enhancing screening methods and metabolo-genomics approaches.