M.Sc. DissertationFall armyworm (FAW), Spodoptera frugiperda (J. E. Smith) was reported for the first time in Africa in 2016 from America. FAW is widely distributed in Tanzania, causing significant damage to maize. Two factor, cropping systems and biopesticides were tested in Randomized Completely Block Design arranged in a two - way factorial experiment with three replications for their efficacy against FAW and associated parasitoids on maize field at Crop Museum of Sokoine University of Agriculture (SUA). Cropping systems tested included maize sole crop, maize + cowpea, and maize + desmodium and napier grass (push pull system). Biopesticides tested included Metarhizium anisopliae and Beauveria bassiana. The insecticide flubendamide was applied as a positive control, between August 2018 - December 2018 and December 2018 - March 2019 cropping seasons. In the laboratory sampled FAW egg masses and larvae were reared, emerged parasitoids were recorded. Three species of parasitoids (Chelonus bifoveolatus, Coccygidium luteum and Cotesia sp) were recovered. Results showed that C. bifoveolatus was mostly dominant parasitoids. However, highest parasitism rates were in Cotesia sp in push pull plots treated with M. anisapliae in season 1 and 2 (13.7% ± 0.14 and 14.5% ± 0.17 ) respectively. Abundance of parasitoids was significantly affected by cropping systems (p ˂ 0.01) and sampling weeks (p ˂ 0.001 for season 1 and p ˂ 0.01 for season 2) and percept damaged maize plants by FAW was significantly affected by cropping systems (p ˂ 0.001) pesticides (p ˂ 0.001) and cropping systems x pesticides application (p ˂ 0.01). Furthermore, highest maize grain yields and cost benefit ratio were estimated in push pull and cowpea + maize cropping systems compared to sole maize. These results prove that, biological control are effective and involves conservation of natural enemies for sustainable control of FAW.