This study aims to evaluate the insecticidal activity of four bacterial strains against M. cerasi under both laboratory and field conditions, in order to provide a more sustainable and eco-friendly alternative to chemical insecticides. Four environmentally friendly bacterial strains were evaluated for their potential as biocontrol agents: Brevibacillus brevis (FD-1), Bacillus cereus (FD-63), Bacillus thuringiensis subsp. kenyae (FDP-8), and Bacillus thuringiensis subsp. kurstaki (FDP-41). Experiments were conducted under both controlled laboratory and field conditions. Data showed that mortality rates ranged from 33.33% to 93.33% under controlled conditions and from 13.33% to 50% under field conditions over the 96 h period. B. thuringiensis subsp. kurstaki (FDP-41) and B. thuringiensis subsp. kenyae (FDP-8) were the most effective bacterial strains against the aphids in controlled conditions. The percentage of mortality related to these applications was 93.33% and 80% in 96 h under laboratory conditions. However, the effectiveness of B. thuringiensis subsp. kurstaki (FDP-41) was 50% at 96 h in the field. These findings suggest that B. thuringiensis subsp. kurstaki and B. thuringiensis subsp. kenyae hold significant potential as biological control agents against M. cerasi. Additionally, FDP-41 showed the lowest LT50 value of 25.37 h in the laboratory and 86.40 h in the field. This indicates a much more rapid and potent effect on M. cerasi compared to other strains. As a result, it was concluded that these bacterial strains may be used successfully as biocontrol agents in the biological control of M. cerasi. Their successful use could reduce reliance on synthetic insecticides, thereby minimizing pesticide residues on crops and contributing to safer agricultural production and environmental sustainability.