Soybean Aphid

Soybean aphid. Click on image to view a larger version.

Soybean Aphid Research Update 2011 Read online (pdf) or order a free print copy by calling 1-800-383-1423)

The soybean aphid (Aphis glycines) is the only aphid in North America able to develop large colonies on soybeans. It was identified as a pest in North America in 2000. Since then, it has established itself in most soybean-growing areas and is a significant soybean pest in some years.

When the tiny, sap-sucking insects are present in large numbers (several hundred per plant), their feeding can cause stunting, puckered yellow leaves, reduced pod set, and smaller seed.

Agronomic impact

The risk of yield loss is greatest when aphid populations peak during the R1-to-R4 growth stages, when blooms and young pods are most suseptible to stress.

Damage due to aphid feeding increases when growing conditions, especially soil moisture, are below optimum. 

Present and future tools to manage soybean aphids

Management of the soybean aphid is an active area of research in the north central region. Growers now have a toolbox of strategies to work with, including.

• Well-established scouting procedures and an action threshold of 250 aphids/plant.
• Resistant soybean varieties - four resistant gene packages, called "Rag" genes (Resistance: Aphis glycines) have been reported by university researchers. The Rag1 resistance package was available in commercial soybean cultivars in 2011, and others are on the way. Host plant resistance works by inhibiting aphid growth and development and increasing plant tolerance to aphid feeding.
• Biological control - the soybean aphid would be a far more damaging pest were it not for biological control. Be aware of beneficials keeping aphids in check. A major regional research program is in progress with the goal of augmenting resident populations with specialist natural enemies.
• IPM - integrating aphid host resistance with biological control, scouting, insecticides, and crop management practices is the most effective strategy for aphid management. Read the Soybean Aphid Research Update 2011 for a good overview of soybean aphid IPM.