Many predatory arthropods are nocturnal, yet the potential contribution of nocturnal predators to biological control is often overlooked. The soybean aphid, Aphis glycines Matsumura, has emerged as a significant pest of soybean in the North Central US. Soybean aphid biological control research has focused on diurnal predators. Here, we used video cameras to continuously monitor soybean plants infested with soybean aphids, compare the diurnal and nocturnal predator communities on those plants, and assess predator activity during different times of day. Different predator communities were observed being active on soybean during day and night. Coccinellids and anthocorids dominated the diurnal predator community, while Opiliones and Araneae dominated the nocturnal predator community. Nocturnal and diurnal predators were recorded being active for similar rates per hour. Future research is needed to clarify the significance of arachnid predators and other nocturnal generalists to soybean aphid biocontrol.
