Organisms face the dual threats of starvation and predation at the same time. Since foraging and vigilance are assumed to be mutually exclusive, the trade-off between foraging and vigilance would pose a challenge for organisms, requiring them to optimize their behavior. Previous research indicated that when individuals aggregate, interactions among individuals can influence behavior and partially mitigate the trade-off relationships that could not be resolved at an individual level. Recently, there has been accumulating evidence that heterogeneity within a group can lead to emergent changes in the group performance. For instance, in Drosophila melanogaster, a population with behavioral diversity shows a higher survival rate than a population without diversity. However, little is understood about the non-additive effects of genetic and/or behavioral heterogeneity within a group on the behavioral trade-off. Our study aimed to explore the effects of intraspecific diversity on behavior and the foraging-vigilance trade-off using 73 genetically distinct strains of D. melanogaster. We prepared groups consisting of either a single strain (homogeneous groups) or two different strains (heterogeneous groups), exposed them to looming stimuli that resembled a predator, and recorded their behavior for 5 minutes. We quantified the frequency of freezing behavior in response to the visual stimuli as an indicator of vigilant behavior and boldness, spatial comprehensiveness, and locomotive speed as indicators of foraging behavior. We compared the behavioral phenotypes in heterogeneous groups with the expected mean of two homogeneous groups to assess the non-additive effects of genetic heterogeneity. In our experimental condition, both homogeneous and heterogeneous groups indeed exhibited a negative correlation between foraging and vigilance, i.e., foraging-vigilance trade-off. Also, in some heterogeneous groups, non-additive effects appeared in their behavior. A high degree of phenotypic diversity in a couple of traits could be responsible for the non-additive improvement in the mean individual behavior within a group. Additionally, we found that some heterogeneous groups simultaneously improved foraging and vigilance behaviors. Our findings indicate that genetic heterogeneity can partially mitigate the foraging-vigilance trade-off at the group level, leading to higher group performance.