Pest Symptoms / Injury ID

• Shortened plant height
• Curled leaves, often yellow on outside (similar to potassium deficiency)
• Excessive honeydew on leaves, which promotes sooty mold growth
• Presence of ants, which also feed on the honeydew

Pest Facts and Impact on Crop

• Latin name is Aphis glycines Matsumura
   
• Importance
  • Origin in Asia
  • First detected in U.S. near Lake Michigan in 2000
  • Major outbreaks in 2001, 2003, 2005
  • Untreated economic infestations frequently reduce yields by more than 10 bu/acre
• Development
  • Overwinter on buckthorn, move to soybeans in July and back to buckthorn in the fall
  • Host plants include a wide range of legumes (soybean, alfalfa, clovers)

Distribution

Causes of Yield Reduction

• Removal of moisture, nutrients needed for grain production
• Honeydew on leaves where sooty mold grows, which reduces photosynthesis
• Transmission of viruses

• Asian lady beetle - adult or larvae
• Chrysopa/Lacewing - adult or larvae
• Syrphid fly - larvae
• Predatory bugs - Minute pirate bug, Big-eyed bug, Damsel bug, etc.
• Biocontrol agent = Parasitic wasp - Binodoxys communis
• Various fungal diseases

• Soybean aphids are small
  • Less than 1 mm in length
  • Oval or pear-shaped
• Color is typically light green
• Adults may or may not have wings
  • Winged adults have black head/thorax
• Cornicles are distinguishing characteristic
  • Black "tail pipes" projecting from the rear of the abdomen
• Aphids develop by gradual metamorphosis in 3 stages:
  • Egg (fall and winter only)
  • Nymph (resemble small adults)
  • Adult (may or may not have wings)

Management Practices for Soybean Aphids

• Population factors
  • Consider using seed treated with a nicotinoid insecticide to delay soybean aphid population establishment, especially in late plantings
  • Temperatures in the low to mid 70s promote longevity and reproduction (doubling time is less than 2 days)
• Scout fields in July
  • Use economic threshold of 250 aphids per plant to justify insecticides
• Insecticide control
  • Spray fields before aphids reach 1,000 per plant and plant stage R5.5

• Plant resistance
  • Natural antibiosis - Monitor varieties with least antibiosis first
  • Natural antixenosis
  • Future Pioneer® brand varieties with array of Rag genes may reduce need to spray