The present study evaluate the bio-effect of coriander seed extract alone and under MAs of microhabitat harvested food in hermetically sealed conditions with low oxygen and high carbon dioxide i.e. 25%, 50% C02 and 99.8% nitrogen under 27 :I: 20C and 60 :I: 5% RH against adults of Sitophilus oryzae (L.), Rhizopertha dominica (Fab.) and Tribolium castaneum ( Hbst.) at in stored grain insects lab., Faculty of Agriculture, Moshtohor, Zagazig University. Results obtained revealed that, the effectiveness depends first on the coriander extract concentration, exposure period and tested insect species. The extract at 1 % wjw was the most effective to R. dominica adults hence the adult mortality reached 75.5% after two weeks, while it was 30% and 9.9% for S. oryzae and Tribolium castaneum. respeitively In respect to 25% C02 micro-habitate atmosphere (MA). The adult mortality demonstrated 100% for T. castaneum after 3 days of exposure, while it was 56.6 and 87.7% for both S. oryzae and R. dominica,. respeitivtively Complete mortality was achieved for R. dominica and S. oryzae survivors after 5 and 7 days, respectively. The modified micro-habitat atmospheric conditions (MA), containing of 50% C02 demonstrates complete mortality of the three tested insects species after three days of treatment. Similar results were in respect to the reduction parameter expressed as percentage (%) of the adult emergence (%). The atmospheric micohabitat containing 99.8% N2 showed complete mortality of S. oryzae and R. dominica after 5 days exposure period, while it was 88.8% for T. castaneum. The joint action of extract with the three modified atmospheres figures were used depends mainly on extract concentration, insect species and type of the modified atmosphere, physical factors prevailed. Results revealed the presence of reliable synergistic effect for S. oryzae individuals at 25% C02 and 25% extract, on the other hand additive effect was reported for R. dominica and T. castaneum. At 50% C02 and 5% extract, the resultant effect demonstrated additive for the three insect species. The microhabitat components of 99.8% N2 with 5% of the extract showed reliable additive effect after 3 days from exposure period with the three insect species.