The present work was carried out to evaluate the toxicity of four pesticides i.e. Abamactin, Bifenazte, Spinossad and Beauvaria bassiana against Tetranychus urticae Koch and predator mite comparing with release the predator mite, Phytoseiulus persimilis Athias-Henroit on Cucmber plant, Cucumis sativus that were assessed in greenhouse. Fabcomic, Acramite, Tracer and Biovar were much less toxic to adult females and immature of P. persimilis than to those of T. urticae. Chemical pesticides gave its maximum reduction after 3 days from treatment, 86.04, 72.61 and 76.52%, respectively for Fabcomic, Acramite and Tracer, while Biovar was the least. On the other hand releasing of P. persimilis at level 1:10 gave the best results of bio-control T. urticae infesting cucumber plant where it gave 26.09% reduction after 3 days from released and the reduction percentage increased gradually until reached its maximum values after 14 days with 88.41%. These results were nearly similar to those gave by other pesticides. P. Persimilis significantly affected by feeding on treated prey where longevity and fecundity decreased.
Conclusively, the predatory mite, P. persimilis introduced good results in controlling the two-spotted spider mite, T. urticae on cucumber plants in green houses. So, it can use as a biocontrol agent in controlling this dangerous mite pest on other plants, but it would be appear that conjoint use of the tested pesticides with P. persimilis in IBM have be sequence separated by time intervals that would be sufficient to minimize the toxicity effects on the predator.