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Soybean Aphid

 
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Soybean Aphid

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Pest Symptoms / Injury ID

Aphid-infested soybean leaves
Soybean aphid-infested soybean leaves.
  • 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
Soybean field infested with soybean aphid
Plants infested by soybean aphid are shorter.

 

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)
close-up of soybean aphid
Distribution
U.S. map of soybean aphid distribution
Soybean aphid distribution and area of increased probability of economic infestation.
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
Soybean leaves blackened due to sooty mold
Soybean leaves blackened due to sooty mold.

Natural Enemies

  • 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
Natural enemies of soybean aphids

Pest ID

  • 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)

 

Soybean aphid nymphs and adults
Soybean aphid nymphs and adults

Life Cycle

Life cycle of the soybean aphid
 

 

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)
  • Allow lady beetles, insidious flower bugs, and other beneficial insects to suppress populations
  • 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

      sprayed and unsprayed field for soybean aphids
  • 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

 

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