Considering the undeniable need to use synthetic pesticides in agriculture, there are new steps to find new pesticides and new ways to manage them to act safer to human and the environment. In this study, the toxicity of thiacloprid and fenvalerate were tested under field conditions at recommended field rates on the black bean aphid, Aphis fabae Scopoli (Hemiptera: Aphididae), and also evaluated

biosafety against its parasitoid, Lysiphlebus fabarum. This aphid is one of the most polyphagous sap-sucking pests that make primary and secondary damages to more than 200 leguminous host plants. While L. fabarum plays an important role in the control of A. fabae (3-79% parasitism in different conditions), insecticides must be used in special conditions to reduce their adverse effects.The Black bean aphids were sprayed with the insecticides or water after adaptation on the Vicia faba leaves. Thiacloprid and fenvalerate caused 89.21±3.6% and 81.14±4.2% mortality against aphids, respectively. The insecticides were also applied to the immature stages of parasitoid which were exposed to the materials by briefly dipping mummified aphids into insecticide emulsion or water (control). 34.65±1.91%, 11.64±1.38% and 38.79±1.84% of adults emerged after exposure to thiacloprid, fenvalerate and control, respectively. Results demonstrate that both insecticides have significant mortality effects on A. fabae, while thiacloprid does not significantly reduce the adult emergence of L. fabarum. Based on these results, thiacloprid could be used and classified as a slightly dangerous insecticide to L. fabarum in immature stages, but mortal to A. fabae.