Tomato leaves showing severe mosaic, leaf puckering, filiformism and stunted growth were collected and identified as CMV subgroup II. A single strain A25 was selected because of their protective effect against CMV-induced diseases, growth promotion & identified as Bacillus subtilis and the strain is referred to as BS3A25. The growth parameters of the aphid A. gossypii were found to be restricted in the BS3A25 supernatant treatment.The present study also recorded the higher activities of PAL, PO, Phenols, CAT, PPO in plants treated with BS3A25 speculating of induced defense responses in plants. The results of field study indicated that the treatment consisted of BS3A25 formulation for seed and BS3A25supernatant formulation for foliar treatment proved highly effective in reducing the aphid population than treatment with seed and foliar spray of imidacloprid.BS3A25 gave significantly higher yield (34.08 tonnes/ha.) compared to imidacloprid treatment (31.12tonnes/ha.) and control plants (20.0 tonnes/ha.).The highest cost: benefit ratio (1:2.5) was obtained following the treatment with BS3A25 formulation than imidaclopid (1:2.0)and control plants(1:1.4).