Aphids

Aphids are small insect pests with oval-shaped green, brown or black bodies. Often occurring in colonies, aphids suck on sap, causing loss of vigour, and in some cases yellowing, stunting or distortion of plant parts. Honeydew (unused sap) secreted by the insects can cause sooty mould to develop on leaves. When aphids transmit viruses, the impact on crop growth and yield can be significant. The earlier the transmission of virus, the greater the potential impact.

Direct aphid feeding rarely causes major damage to broadacre crops, and control measures are generally unnecessary, as parasitoids and predators keep populations in check. Exceptions occur when aphid populations are extreme (particularly early) or the compensatory ability of the crop is compromised by stress (particularly moisture stress), and aphid impact on flowering or pod set/fill may be significant.

See also the following pages

Life cycle diagrams (in pdf) are available for the following aphid groups: Cabbage aphid | Cereal aphid | Green peach aphid | Turnip aphid | Winter cereal aphid

Aphid species

Crops infested

Alternative hosts

Virus transmission

Impact on crop
Turnip aphid Canola (Generally restricted to cruciferous crops and weeds) Wild radish and wild turnip Reduced pod set, pod fill and seed quality.
Cabbage aphidcabbage aphid Canola (Generally restricted to cruciferous crops and weeds) Wild radish and wild turnip Reduced pod set, pod fill and seed quality.
Blue green aphid Canola Pulses Pastures Pasture legumes Lucerne and pasture: damages terminal buds, upper leaves and stems.
Green peach aphid Canola Wild radish and wild turnip, lupins, capeweed plus others Beet western yellows virus (BWYV) Early season pest, with potential to impact on yield through transmission of BWYV. Rarely persists to cause direct yield loss.
Cowpea aphid Pulses Pasture legumes potatoes Cucumber mosaic virus (CMV) in lupins, lentils, faba beans, chickpeas Bean yellow mosaic virus in faba beans, lupins Alfalfa Mosaic virus (AMV) in lentils, lupins, chickpeas
  • Impact on yield through the transmission of viruses.
  • Early infestation and virus transmission has the greatest impact on crops.
  • Infestations during flowering, reduce pod set and pod fill.
Oat aphid Winter cereals Pasture grasses Barley yellow dwarf virus (BYDV)
  • Early infestation and virus transmission poses greatest threat to yield.
  • Direct feeding by aphids can retard plant growth, but the impact on yield in not well understood.
Corn aphid Sorghum Winter cereals Pasture grasses Barley yellow dwarf virus (BYDV) Sorghum: Adults and nymphs suck sap and produce honeydew. Honeydew can cause grain stickiness at harvest if aphids persist. Cereals: Aphids feed on stems, leaves and heads, but the impact on yield is not well understood. Very early infestations can retard plant growth
Rose grain aphid Winter cereals Grasses Barley yellow dwarf virus (BYDV)
  • Later season infestation.
  • Colonies common on leaves.
  • Impact on yield unclear.
Russian wheat aphidrwa1 Barley and wheat highly susceptible. Oats tolerant. Other winter cereal crops intermediate. Grasses. Not known to build up in sorghum Can transmit BYDV, but not as effective a vector as the other cereal infesting aphid species. Yield loss as a result of reduced photosynthetic capacity of infested plants. Whitening of leaves and rolling reduce effective leaf area. In very severe infestations, seedlings may die. Infestation at head emergence can result in rolling of the flag leaf, trapping the emerging head and significantly affecting yield.
Soybean aphid Soybeans Not known to transmit virus within Australia. In China, soybean aphid transmits soybean mosaic virus, which can cause yield loss and decreased seed quality.
  • Infested plants can have distorted leaves
  • May be covered in sooty mould.
  • Heavy infestations can reduce yield and delay harvest maturity