Roles of environmental factors in shaping soybean aphid populations

Population dynamics for outbreak pests are often difficult to grasp, especially when they are potentially influenced by a number of particular factors. The soybean aphid, for example, is a sporadic outbreak pest of economic importance because of its ability to affect soybean yields. Numerous studies have shown soybean aphid populations to be influenced by numerous abiotic and biotic factors acting at different spatial and temporal scales. Examining these patterns across spatial and temporal scales is crucial to better understand and control the pest population. Soybean fields were sampled during growing seasons of 2011, 2012 and 2013 in North Dakota and Minnesota. Data was collected regarding soybean aphid populations, natural enemy communities, presence of other arthropods, soybean plant growth, soil type, and general climate data. Using non-metric multidimensional scaling we compared arthropod communities of soybean fields to see how they differed across space and time. We found arthropod communities across different fields in a given year were more similar to each other than the communities of fields that were managed the same way or were in the same location each year. These results seem to differ from previous studies that showed the importance of spatial location and landscapes. Our results may indicate seasonality or weather conditions in a given year as important determinants of soybean arthropods and soybean aphid populations. Recognizing specific factors driving this pattern, and the relative amount of influence and spatial range of each factor, would provide beneficial information to producers and provide insightful information for aphid ecology.