Greenhouse Studies of Soybean Aphid Effects on Plant Growth, Seed Yield, and Composition

Authors: Riedell, Walter; CATANGUI, MICHAEL - SOUTH DAKOTA STATE UNIV

Submitted to: Journal of Agricultural and Urban Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2008
Publication Date: 4/15/2008
Citation: Riedell, W.E., Catangui, M.A. 2008. Greenhouse Studies of Soybean Aphid Effects on Plant Growth, Seed Yield, and Composition. Journal of Agricultural and Urban Entomology. 23(4):225-235.

Interpretive Summary: Because soybean is an important crop in the U.S., development of an integrated pest management system for soybean aphid is a high priority research need. Integral components of IPM programs for pest population management is knowledge of the effects of pest injury on plant growth, yield, and seed composition. The objectives of this study were to measure the effects of soybean aphid infestation, applied at different soybean development stages, on soybean plant growth, yield, and seed composition. Aphid feeding during the vegetative stages increased internode elongation, increased stem length, and increased individual seed weight. Aphid feeding injury during reproductive stages tended to reduce the individual seed weight, but this reduction did not translate into reductions in yield. Thus is appears that the soybean plants were able to compensate for feeding injury imposed during the reproductive phase so as to ameliorate yield loss. Large decreases in oil concentration were observed in plants infested in the reproductive stages. Because of the intimate association between lipid bodies, chloroplasts, and fatty acid synthesis in soybean and the reduction in photosynthesis caused by soybean aphid feeding, it is not unexpected to see the dramatic reductions in seed oil concentration in soybean injured by soybean aphids. Even though aphid injury in this study did not lead to a significant loss in total seed yield, measured differences in oil concentrations suggest that seed composition responses to aphid injury should be an important consideration when conducting research to develop IPM systems for this soybean pest.

Technical Abstract: There is little published information available that describes the effects of soybean aphids (Aphis glycines Matsumura) on soybean [Glycine max (L.) merr] growth, yield, and seed composition. The objective of this research was to measure how soybean growth, yield, and yield components are affected by soybean aphid infestations under controlled environments. Greenhouse-grown plants were infested with aphids at the first node stage (V1), the third node stage (V3), the beginning bloom stage (R1), the full pod stage (R4) and the beginning maturity stage (R7). Aphids remained on the plants for a total of 6000 aphid-d (e.g. 600 aphids present for 10 days) after which the insects were removed with insecticide. Increases in stem length, as compared to uninfested controls, were observed in plants infested at the V1 and V3 stages but not at the R7 development stage. Aphid infestation had no significant effect on seed yield, number of pods plant-1, or number of seeds pod-1. Aphid treatment reduced seed number plant-1. Individual seed weights were greater in aphid infested plants than control when treated at the V1 and V3 development stage but were not different when aphids were applied to plants in the reproductive stages. Seed protein concentration was not affected by aphid infestation treatment. Infestation at the R4 and R7 stages resulted in dramatic reductions in seed oil concentrations compared with controls. Even though aphid injury in this study did not lead to a significant loss in total seed yield, aphid-induced reductions in oil concentration suggest that seed composition responses to aphid injury should be an important consideration when conducting research to develop IPM systems for this soybean pest.