The aim of this thesis is to comparatively elucidate the mechanisms of action of insecticides that target the digestive system of insects and to highlight their selectivity, effectiveness, and risks to non-target organisms. A review and comparative analysis of the literature was conducted with a focus on the midgut as a functional barrier and primary target for insecticides, where key processes of digestion, absorption, and detoxification take place. The findings indicate that after activation in the lumen, Bacillus thuringiensis endotoxins cross the peritrophic matrix, bind to specific receptors on the enterocyte membrane, and trigger pore formation or enterocyte death, which leads to disruption of the gut barrier. Transgenic plants can further reduce the digestive efficiency of pests by expressing inhibitors of key enzymes (e.g., endopeptidases, α-amylases) or lectins, while among newer approaches RNAi and CRISPR/Cas technologies stand out for gene-specific silencing or modification of targets in the midgut epithelium. The efficacy of RNAi depends on the uptake of dsRNA into enterocytes, its release from endosomes into the cytosol, and the activity of complexes Dicer/RISC. The main limitations are molecular instability and pronounced interspecific differences of insects in susceptibility. In conclusion, the insect midgut is a promising target for more selective and environmentally acceptable approaches. However, substantial further research is required before these methods can be widely implemented in practice.
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