Survey of soybean aphid populations in the Red River Valley and potential influencing factors

A number of biotic and abiotic factors have the potential to influence herbivore populations, but recognizing which factors are important can be difficult. The soybean aphid is an eruptive arthropod pest capable of causing significant yield losses. Thus, it is worthwhile to investigate factors that can affect soybean aphid population densities. It is important to consider that management strategies implemented in agroecosystems can have a multitude of possible effects on insect communities, particularly herbivore pests and their natural enemies. During the growing seasons of 2011, 2012, and 2013 we surveyed organic and conventionally managed soybean fields located along the Red River Valley (ND and MN). Fields were paired by location (4-5 pairs) so that each organic field was near a conventionally managed counterpart. We measured a number of biotic and abiotic factors that may be expected to differ with management strategies. Through various sampling techniques we quantified insect densities at weekly or bimonthly intervals throughout each season. This data was then used to quantify differences in insect populations within the fields surveyed. Such patterns could help lead to a better understanding of insect communities in agroecosystems, which can lead to additional studies of how these communities are created and their impact on herbivorous pests. The results of this study could also potentially provide insight into the causative abiotic factors behind variations in soybean aphid population densities.