Effect of different intercropping systems of sweet basil (Ocimum basilicum) plants and spraying with sweet basil oils on population of Green bean (Phaseolus vulgaris) L. pests (Bemisia tabaci (Genn.), Liriomyza trifolii (Burg.) and Tetrenchys urticae (Koch)) under three agricultural ecosystems namely; plastic greenhouse, scaffold net greenhouse and open field, an experimentwas carried out inside greenhouse experimental area at Dokki, Giza Governorate during 2012. According to interaction between of intercropping system and agricultural ecosystems on the level infestation with certain green bean pests, it is clear that, plastic greenhouse harboured the highest number of pests infesting green bean plants while the open field had the lowest number of pests whereas, the scaffold net greenhouse was intermediate as a result to spraying with basil oil is the best method to reduction the number of pests attacking green bean irrespective of intercropping with basil plants or cultivating under plastic or scaffold net greenhouse.