Submitted to: Crops and Soils
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/2/2008
Publication Date: 6/18/2008
Citation: Beckendorf, E.A., M.A. Catangui, W.E. Riedell. 2008. Soybean Aphid Feeding Injury and Soybean Yield and Seed Composition. P. 17-21. In: B. Erickson (ed.) Crops and Soils, Summer 2008. www.agronomy.org. Interpretive Summary: The soybean aphid, a common soybean insect pest in Asia, was first found in Wisconsin during July 2000. Once established on a plant, soybean aphid populations can increase logarithmically via asexual reproduction. Soybean aphids also can develop winged form body morphology during summer months which allows the insect to spread through the air to infest large geographic areas, even in areas where the aphid does not overwinter. By 2003, the insect was found in 21 U.S. states and 3 Canadian provinces and is now considered to be a major soybean insect pest in the north central US. Predictions are that this insect will expand its range to include all regions of the US where soybeans are grown. Because the soybean aphid is a relatively new pest in the U.S., a comprehensive integrated pest management (IPM) approach to manage aphid populations has yet to be developed. We felt that a controlled-infestation field study of how aphid populations affect of soybean growth, yield, and seed composition would be a step toward the development of IPM systems for this invasive insect pest. This 2-yr field study measured aphid populations and the effects of those populations on soybean seed yield, yield components (shoot biomass, pods plant-1, seeds pod-1, and 100 kernel weight), and seed composition (oil and protein concentrations) when infested at the vegetative (V5) or reproductive (R2) development stages. Relating these aphid population parameters at the plant growth stages studied enables producers to make informed decisions about the need for and timing of rescue chemical treatments.
Technical Abstract: Accurate prediction of the level of yield loss caused by soybean aphid feeding is considered to be the crux of integrated pest management for these pests. Despite the accumulating literature on the soybean aphid, there are currently few published data on the effects of soybean aphid populations on soybean yield and seed components for soybeans grown in the United States. Thus, the objectives of this study were to quantify aphid populations and the injuries caused by those populations on plant biomass, seed yield, and components (total yield, pods plant-1, seeds pod-1, individual seed weight, oil concentration, protein concentration) in plants infested at the vegetative and reproductive development stage. Our results indicate that the reproductive potential of the soybean aphid was very high. A single aphid per plant introduced at the vegetative stage, for example, multiplied to a peak of 4627 aphids per plant and resulted in 101076 maximum cumulative aphid-days per plant. We also observed that seed yield, yield components, and seed oil percent declined linearly as peak aphid numbers per plant and maximum cumulative aphid-days per plant increased. We feel that relating these aphid population parameters at the plant growth stages studied to yield responses by this economically-important crop enables producers to make informed decisions about the need for and timing of rescue chemical treatments against the soybean aphid.