Imidacloprid and the fungus Beauveria brongniartii (1x102 to 1x108 conidia/ml) were evaluated against the green peach aphid, Myzus persicae (second instar) and their predator Coccinella undecimpunctata (day-old adults) in tomato plantations in two different climatic Governorates Dakahlia and EL Behira. Using a spray technique to evaluate contact effect and a feeding technique to evaluate oral toxicity. Our results showed that under laboratory conditions, the LC50 values of Imidacloprid and B. brongniartii were 66 ppm and 72 conidia /ml, respectively against M. persicae. Under field conditions, the percentages of infested plants with M. persicae were significantly decreased after treatments with both Imidacloprid and B. brongniartii as compared with the corresponding controls. In El- Esraa Nobaryia (Behira) and El Dakahlia, the weights of tomato yield were 4978± 74.31 kg/feddan (F) and 4597±65.12 Kg/F in Imidacloprid plots treatments. The percentages of yield loss ranged between 24, 49 and 22, 50 in El- Esraa Nobaryia (Behira) and El Dakahlia, respectively. The study showed that C. undecimpunctata exhibit relatively high and reasonable resistance to Imidacloprid and Beauveria brongniartii at their highest lethal concentration for tested prey.