According to the principles of integrated plant protection, biological pest control is always given priority over chemical pest control. However, in some situations it is not possible to achieve the desired effect by biological control, so it must be combined with chemical control. In this case, only a selective insecticide can be combined that will "spare" the natural enemy and at the same time control the pest. In the process of registration of plant protection products, it is necessary to determine their effect on natural enemies through research, most often testing the effect on two parasitic wasps, Encarsia formosa Gahan and Trichogramma cacoeciae Meyer, and on the predatory mite Phytoseiulus persimilis Athias-Henriot. The aim of the study was to determine whether the insecticide A19526X based on the new active substance has a residual effect on the mummy of the parasitic wasp Aphidius colemani Viereck (Hymenoptera: Braconidae) and what is its impact on the biotic potential of wasps that developed from treated mummies. Two commercial insecticides (spirotetramate and imidacloprid), the investigated insecticide A19526X in three different doses and untreated control were included in the study. The experiment was conducted in six variants with five repetitions. For the test of direct contact action, parasitic wasps mummies were treated with insecticide and the release of newly emerged wasps was monitored for the next five days. The test did not reveal a negative effect of the investigated insecticide because the percentage of newly emerged wasps was the same in all variants, including the untreated control. The sex of the surviving wasps was determined, of which a total of 19 females were subsequently subjected to a residual toxicity test. Female parasitic wasps were individually dropped on previously grown pepper plants infected with cotton aphids (Aphis gossypii Glover) that were isolated in cylinders. After 14 days, the percentage of parasitism achieved by wasps developed from treated mummies did not differ significantly from untreated control. Based on the obtained results, the investigated insecticide A19526X can be categorized according to the IOBC scale as harmless and safe for the parasitic wasp Aphidius colemani. Also, the insecticide A19526X can be considered suitable in facilities where chemical and biological pest control measures are applied at the same time. The effect of A19526X insecticide on other types of natural enemies that can be applied in greenhouses should be further investigated.