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 during the overwintering phase; 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

• Outbreaks:
  • Soybean aphids cause direct damage (yield impact) by sucking plant sap. Soybean aphid outbreaks can lead to reduction in pod number, seed size and quality.

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.
• In September and October winged adults move to buckthorn to lay eggs.

Damage/Symptoms

• Symptoms of feeding damage include plant stunting, and/or leaves covered with honey dew (sticky substance excreted by aphids) and black sooty mold, a fungal growth on honey dew-coated leaves.
• Soybean aphids can vector soybean mosaic virus and alfalfa mosaic virus.

Scouting Procedure and Economic Threshold

• Scout soybeans from late vegetative stage/R1 (beginning bloom) through R5 (beginning seed).
• To scout, examine 20 to 30 plants in a field, covering 80% of the field. Check the whole plant, especially leaf undersides.
• When R1 through R5 soybean growth stages reach an average field density of 250 aphids per plant (economic threshold), treatment with a foliar insecticide is recommended. Regular field scouting is required to determine if aphid populations are increasing.
• Regardless of soybean price, treating below 250 aphids per plant results in no detectable yield increase. In addition, early insecticide application below the economic threshold kills beneficial insects allowing soybean aphid populations to rebound more quickly.

Integrated Control

• Biological control: A parasitoid wasp, Binodoxys communis, has been introduced to help keep aphid numbers down. Ladybeetles, lacewings, and minute pirate bugs also help suppress populations.
• Cultural control: Soybeans planted later in the season tend to have higher aphid populations as do fields deficient soil test potassium (K) levels.
• Chemical Control: For current Wisconsin recommendations, consult University of Wisconsin-Extension Publication A3646, Pest Management in Wisconsin Field Crops.

Back to top

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
• Soybean aphid suction trap network

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.

Back to top