Scientific name: Aphis glycines
Order: Hemiptera
Family: Aphididae

Info

Biological Description

• Adults: Small (1/16 inch); soft-bodied; yellow-green
  • Some have wings and some are wingless. Winged aphids have black head and thorax
  • Late in the summer white morphs can appear
• Eggs: Egg stage occurs only when aphids are on buckthorn; otherwise aphids give live birth to nymphs. Eggs are tiny and green or black.
• Nymphs: Nymphs look like adults, only smaller. Can be paler in color.

Economic Importance

• Soybean aphid is only a pest of soybeans.
• Outbreaks:
  • Aphid populations increase faster when plants are under moisture stress.

Life Cycle

• Soybean aphid overwinters in Wisconsin on buckthorn in the egg stage.
• In spring, there are 2 to 3 generations on buckthorn before aphids move to soybeans.
• Soybean aphids migrate to soybeans in June. There are many generations of mostly wingless females.
• Population growth increases when soybeans are under moisture stress.
• Populations increase the most when soybeans are in the late vegetative and early reproductive stages.
• In September and October winged adults move to buckthorn to lay eggs.

Damage/Symptoms

• Damage includes plant stunting; yellow, puckered leaves; and reduced pod numbers.
• Risk of yield loss is greatest when the aphid population peaks as soybeans are beginning to flower.
• Soybean aphids can transfer soybean mosaic virus and alfalfa mosaic virus.
• When an infestation is severe stems and pods are covered; honeydew and sooty mold cover bottom leaves; and plants are stunted.

Scouting Procedure and Economic Threshold

• Start spot checking soybeans when they are seedlings and continue scouting through pod set.
• Intensify checking in July when aphid populations are likely to increase quickly. This is also generally around late vegetative and early reproductive soybean stages when timely spraying will have the greatest yield return.
• To scout, examine 20 to 30 plants in a field, covering 80% of the field. Check the whole plant, especially leaf undersides.
• If the average number of aphids per plant is 250 and numbers are increasing (at least two scouting efforts will have to be made to determine this), treatment is recommended.
• Spraying is most effective when beans are between R1 and R4 stages. After R6 spraying is not effective. Spraying before mid-July kills beneficial insects and only temporarily decreases the number of aphids present.

Integrated Control

• Natural control: A parasitoid wasp, Binodoxys communis, has been introduced to help keep aphid numbers down. Ladybeetles, lacewings, and minute pirate bugs also help control populations.
• Cultural control: Soybeans planted later in the season tend to have higher aphid populations.
• Chemical Control: For current Wisconsin recommendations, consult University of Wisconsin-Extension Bulletin #A3646, Pest Management in Wisconsin Field Crops.

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Site Links

Insect Images

• Soybean pest images

Extension Publications

• Identification of soybean aphid and look-alike species. Herbert, A., Malone, S., Cullen, E. and Ratcliffe, S. 2007. USDA CSREES North Central Region IPM Publication.
• Soybean aphid research update. 2008. North Central Region IPM Publication.
• Reproductive soybean development stages and soybean aphid thresholds. Fischer, D., Fanta, J. 2004. UW Extension Publication.
• A visual guide for soybean aphid scouting. Proost, R., Jensen, B. UW Extension Publication.

Websites

• UW Soybean Plant Health: Soybean aphid
• ipm-Pest Information Platform for Extension and Education - (up-to-date reports on soybean aphid distribution throughout North America)
• Soybean aphid suction trap network

Extension-Based Conference Proceedings

• Current and developing soybean aphid scouting protocols. Cullen, E. 2008. pp. 197-200. In Proceedings of the 2008 Wisconsin Fertilizer, Aglime, and Pest Management Conference. University of Wisconsin, Madison, WI.
• Soybean aphid suction trapping. Cullen, E. 2006. pp. 108-114. In Proceedings 2006 Wisconsin Fertilizer, Aglime, and Pest Management Conference, University of Wisconsin, Madison, WI
• Soybean aphid in the Midwest : Looking toward a dynamic threshold - emerging recommendations, lingering questions. Cullen , E.M., Gaska, J., Myers, S., Jensen, B., Grau, C., Borges, R. 2004.pp. 68-72. In Proceedings Illinois Crop Protection Technology Conference, University of Illinois, Urbana-Champaign, Illinois.

Wisconsin Crop Manager Articles

• Soybean aphid increasing and variable--Scout fields now. Wisconsin Crop Manager, Vol.15 No.20, July 24, 2008. Cullen, E.
• Soybean Aphid Update for Late August 2008. Wisconsin Crop Manager, Vol.15 No.24, August 21, 2008. Cullen, E.
• Soybean aphid fall flight: destination buckthorn. Wisconsin Crop Manager, Vol.14 No.1, January 18, 2007. Cullen, E.
• Soybean aphid biological control ... An exotic approach. Wisconsin Crop Manager, Vol.14 No.11, May 17, 2007. Cullen, E.
• Soybean aphid scouting and management recommendations 2007. Wisconsin Crop Manager, Vol.14 No.19, July 12, 2007. Cullen, E.
• Critical to watch soybean aphids as temperatures cool. Wisconsin Crop Manager, Vol.12 No.21: 172-173. Jul. 28, 2005. Cullen, E.
• Soybean aphids and high temperatures. Wisconsin Crop Manager, Vol.12 No.16: 122. Jun. 23, 2005. Cullen, E.
• Guest article feature: planning for the 2005 soybean aphid population. Wisconsin Crop Manager, Vol.12 No.12: 92-93. May 26, 2005. Cullen, E.
• Research Brief: Soybean aphid and soil potassium availability. Wisconsin Crop Manager, Vol.12 No.5: 35-37. Apr. 7, 2005. Cullen, E.

PowerPoint Presentations

• 2007 Pest Management Updates. (Slides 36-51). 2007. Cullen, E.

Webcasts

• Managing Soybean Aphids: How Will Biological Control Contribute?
  A link to 9 talks on the subject.
• Soybean Aphid: Biology in North America (Part I) and Economic Threshold and Injury Level (Part II)
  A link to a 20 minute (I) and 26 minute (II) talk by David Ragsdale, University of Minnesota

Refereed Journal Articles

• Kraiss, H. and E.M. Cullen. 2008. Insect growth regulator effects of azadirachtin and neem oil on survivorship, development and fecundity of Aphis glycines (Hemiptera: Aphididae) and its predator, Harmonia axyridis (Coleoptera: Coccinellidae). Pest Management Science 64: 660-668.
• Kraiss, H. and E.M. Cullen. 2008. Efficacy and non-target effects of reduced-risk insecticides on Aphis glycines (Hemiptera: Aphididae) and its biological control agent, Harmonia axyridis (Coleoptera: Coccinellidae). Journal of Economic Entomology 101: 391-398.
• Ragsdale, D. W., B. P. McCornack, R. C. Venette, B. D. Potter, I. V. MacRae, E. W. Hodgson, M. E. O'Neal, K. D. Johnson, R. J. O'Neil, C. D. Difonzo, T. E. Hunt, P. A. Glogoza, and E. M. Cullen. 2007. Economic threshold for soybean aphid (Hemiptera: Aphididae). Journal of Economic Entomology 100: 1258-1267.
• Hodgson, E.W., B.P. McCornack, K.A. Koch, D.W. Ragsdale, K.D. Johnson, M.E. O'Neal, E.M. Cullen, H.J. Kraiss, C.D. DiFonzo and L.M. Behnken. 2007. Field validation of Speed Scouting for soybean aphid. Crop Management doi:10.1094/CM-2007-0511-01-RS.

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