Unravelling the Genetic Basis of Insect Resistance in Maize: Progress and Future Challenges

Maize, the queen of cereals, is generally affected by several insect pests throughout its lifecycle and by post-harvest pests, which affects yield and grain quality, resulting in heavy reliance on chemical insecticides. Although host-plant resistance is environmentally friendly, its polygenic inheritance, genotype-by-environment interactions, the defence-yield trade-off, and pests' ability to adapt quickly make it imperative for researchers to understand the genetic architecture in order to initiate insect resistance breeding programs in maize. This review critically summarises the genetic, biochemical, and physiological baseis of insect resistance in maize, including mechanisms of antixenosis, antibiosis, tolerance, structural barriers, benzoxazinoids, protease inhibitors, and herbivore-induced volatiles and jasmonate-mediated signalling. It also assesses the advancement of germplasm screening, conventional and marker-assisted breeding, quantitative trait locus mapping, genome-wide association studies, genomic selection, clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated protein (Cas) genome editing, and transgenic Bacillus thuringiensis (Bt) technologies. It seems that for durable resistance to be achieved, it will be necessary to combine complementary defence mechanisms rather than relying on single loci or toxins. Future progress needs to incorporate landrace and wild-relative diversity into high-throughput phenotyping, pangenomics, multi-omics, multi-environment prediction, functional validation, and resistance management. This integrated approach can facilitate the development of higher-yielding, climate-smart, multi-pest-resistant maize and minimize pesticide use and associated environmental impacts.