Understanding how changes in biodiversity affect the function of agroecosystems is paramount to conservation biological control. The Species Assemblage Control Hypothesis predicts increasing species richness of predator assemblages can increase the assemblages' ability to suppress pests. I hypothesized that an increase in species richness of a predator assemblage leads to an increase in prey mortality and predator species identity can alter the relationship. An assemblage of predators identified from an assessment of a collard agroecosystem was evaluated to find that only some predators fed on larval Pieris rapae, they did not differ in their per capita consumption, and some intraguild predation occurred. In testing the hypotheses I found a significant relationship between predator species richness and prey mortality; however, predator species identity altered the relationship. These findings highlight the importance in understanding predator assemblages before conservation decisions that effectively suppress pests can be made.