Aphids are ubiquitous herbivores, and many species act as pests on economically important crops. Therefore, it is vital to understand how aphid communities react to changing environmental conditions. Understanding the distribution, abundance, and diversity of pest aphid species helps to inform crop management practices. The goal of this study was to determine the effect of environmental variation over large, regional spatial and temporal scales on aphid community structure. We postulated that accumulated degree days, pesticide application and land use patterns would correspond to observed variation in aphid community structure. Specifically, we postulated that the invasive soybean aphid (Aphis glycines) populations would increase in relative abundance and dominate the aphid community as temperatures increased, due to its high biological potential for reproduction and survival at warmer temperatures. Aphid suction traps were placed over agricultural fields spanning the states of Iowa, Illinois, Indiana, Kansas, Kentucky, Michigan, Minnesota, Missouri, South Dakota, and Wisconsin. Traps were checked every seven days from April-December over 2005-2013, and insects were identified to the highest taxonomic precision possible (usually species).
Results/Conclusions
A total of 714,500 individuals were captured across 230 aphid species comprising 73 genera over the 9 year period. Aphid communities were variable over time, with differences between years and across spatial scales (PERMANOVA, p<0.01). In general, numbers of aphids increased in states where more cropland was planted, and communities varied with dominant crop present in that state. Soybean aphids dominated the community during the early years in our study period; however, this species declined in number and only sporadically dominated the community in the latter years of the study. Although single-species analyses focusing on particular crop pests are common, our results provide some of the first information documenting aphid community responses across long temporal and spatial scales.