Western flower thrips (Frankliniella occidentalis (Pergande, 1895)) is polyphagous pest of North American origin that feeds on more than 250 different plant species. It is important insect pest of many horticultural crops grown in greenhouses. They feed on all above ground plant parts causing both direct and indirect damage to plants. Populations of western flower thrips are difficult to mitigate because of its biology and it takes a lot of knowledge in order to do it successfully. Effective suppression is possible with implementing measures of integrated protection in combination with chemical or biological protection. Due to increasing restrictions on the registration and use of plant protection products in the EU and the fact that the number of active substances in insecticides market in Croatia is declining, there is a need for finding and examining the possibility of using some ecological plant protection products. The discovery of synthetic insecticides has unfortunately displaced the use of botanical insecticides that were previously used in agricultural production. One of underutilized and long known natural insecticide is neem whose main active compound is azadirachtin. Also, the use of various fertilizers or reinforcements for plants can reduce damage on plants. The aim of this master thesis was to investigate systemic effect of azadirachtin (preparation 'NeemAzal') and preparation based on organic nitrogen fertilizer ('Boundary') against adults of western flower thrips on bean leaves. The results showed that although azadirachtin is not sufficiently effective against western flower thrips adults, it reduces their feeding damage on the leaves and prevents egg laying, thus interrupting the life cycle of insect pest. 'Boundary' did not show a good efficacy in this experiment, but it effects thrips feeding and reduces damages on bean leaves.