Title: Relationships between soybean shoot nitrogen components and soybean aphid populations Authors
Submitted to: Arthropod-Plant Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 21, 2013
Publication Date: October 31, 2013
Citation: Riedell, W.E., Beckendorf, E.A., Catangui, M.A. 2013. Relationships between soybean shoot nitrogen components and soybean aphid populations. Arthropod-Plant Interactions. 7:667-676. Interpretive Summary: The soybean aphid, Aphis glycines (Matsumura), was first detected in the U.S. in 2001. This invasive insect expanded its geographic range and is currently considered to be a major insect pest of soybeans in the north central U.S. Because soybean is a major crop of economic importance in the U.S., development of integrated pest management systems and soybean varieties resistant to soybean aphids are important priorities. Basic understanding of how the physiological and biochemical characteristics of the soybean crop interact with aphid population growth is an essential step towards meeting these priorities. We advance in this paper the results of a 2 year field study that tests the hypothesis that concentrations of nitrogen-containing compounds found in soybean shoots will differ across soybean developmental stages and that these differences will be correlated with soybean aphid populations found on those plants. Known numbers of aphids were applied to caged soybean plants at a specific time during vegetative plant growth. Aphid populations, plant growth and biochemical parameters were then measured during the reproductive stages of the soybean plant. Research findings indicate that aphid population dynamics are strongly correlated to the shoot concentration of nitrogen-containing compounds derived from the energy-intensive process of nitrogen fixation. Defining the interrelationships among soybean aphid populations, soybean plant development stage, and nitrogen fixation products may have important implications for breeding aphid-resistant germplasm or in developing crop management practices that reduce soybeans aphid populations without using insecticides.
Technical Abstract: Defining the relationships between soybean (Glycine max [L.] merr.) shoot nitrogen (N) components and soybean aphid (Aphis glycines Matsumura) populations will increase understanding of the biology of this important insect pest. In this 2-year field study, caged soybean plants were infested with soybean aphids (initial infestation of 0, 10, 50, or 100 aphids plant-1) at the fifth node developmental stage. Soybean aphid populations, soybean shoot dry weight, and shoot concentrations of nitrate-N, ureide-N, and total N were measured starting at full bloom through beginning seed soybean development stages. Soybean aphid population as well as shoot concentration of ureide-N increased rapidly starting at full bloom, peaked at beginning seed, and dramatically decreased by full seed soybean reproductive stages. Regression analysis indicated significant relationships (P = 0.01; r = 0.71) between soybean aphid populations and shoot ureide-N concentration. Thus, soybean aphid population levels appear to coincide with shoot ureide-N concentrations in the soybean plant.