The need to find new bioinsecticides is continuously increasing. In this MSc thesis, we tested aegerolysin proteins from oyster mushrooms that had been found to exert insecticidal effects against two plant pests that belong to the Chrysomelidae family: the Colorado potato beetle and the Western corn rootworm. These aegerolysins bind to insect-specific membrane sphingolipid receptor ceramide phosphoethanolamine (CPE) and form transmembrane pores in insect cell membranes in concert with their protein partner pleurotolysin B, which bears a membrane-attack complex/perforin (MACPF) domain. In order to check whether these aegerolysin-based protein complexes are toxic also against other beetles from the Chrysomelidae family, we assessed their toxicity against the cereal leaf beetle (Oulema melanopus) and against the cabbage flea beetle (Phyllotreta atra). The insects were collected on non-treated fields and fed with leaves treated with aegerolysins and aegerolysin/pleurotolysin B mixtures. Our tests showed the sensitivity of cereal leaf beetle to these treatments, while cabbage flea beetles were not susceptible. We also analysed the presence of CPE in lipid extracts from cereal leaf beetle and cabbage flea beetle, as well as from other plant pests (brown marmorated stink bug, Drosophila suzukii, English Grain Aphid, Colorado potato beetle and Western corn rootworm). The presence of CPE was confirmed in all pests’ extracts, but in different concentrations. The highest CPE amount was detected in D. suzukii, and the lowest in English Grain Aphid. The comparison of lipidomic data and toxicity tests showed no correlation between the CPE membrane content and the toxic activity of aegerolysin-based complexes on tested insects.