Integrated Pest Management

APHIDS
HEMIPTERA: APHIDIDAE: Toxoptera citricida

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Identification

Photo of aphid

 

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  • 2mm long

  • Black or brown soft bodied insects

  • Pear shaped body

  • Winged or wingless

  • Cornicicles protruding from abdomen

Associated with flush
Feed in colonies
In heavy infestations honeydew is visible on fruit

Photo

 

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Data Sheet

Damage Symptoms

on fruit

PHOTO

on leaves

Photo

on blossom

Photo

on twigs

Photo

1. On Fruit

Feeding damage Want to know more?
  • Does not feed directly on fruit
  • feeding of aphids causes honeydew ( clear syrup)
     
  • Honeydew attracts ants, which in turn prevent predation of aphids
  • Sooty mould is a phytosanitary problem on fruit
  • It encourages fruit decay after harvesting
     

2. On Leaves

Feeding damage Want to know more?
  • Mouthparts: pierce sucking
  • Plant feeders
  • Feed on “plantsap”
  • Leaves curl backwards (distorted) because of aphid feeding
  • usually on flush
  • populations decrease as flush hardens
  • feeding of aphids causes honeydew ( clear syrup)
  • Severe infestations can reduce fruit set
  • Honeydew attracts ants , which in turn prevent predation of aphids
  • Sooty mould is a phytosanitary problem on fruit
  • It encourages fruit decay after harvest

3. On Blossoms

Feeding damage Want to know more?
  • can attack blossoms
  • usually on flush
  • populations decrease as flush hardens
  • feeding of aphids causes honeydew ( clear syrup)
  • Severe infestations can lead to blossom drop
  • Can cause deformation of blossoms
  • Honeydew attracts ants, which in turn prevent predation of aphids
  • Sooty mould is a phytosanitary problem on fruit

4. On Twigs = see Leaves

Life Cycle

Gradual metamorphosis: nymphs resemble adult

Drawing of life cycle
  • Development of unfertilized egg
  • No males necessary
  • Winged and wingless adults reproduce
r-strategist:
  • high reproduction (infestation levels rise quickly)
  • low survival (can easily be killed)
  • rebound quickly ( after spraying pest levels can rise fast if all predators are killed)
  • Fly away if food source becomes scarce
 

Seasonal Cycle in Vaalharts

Graph
  • Multiply fast on flush
  • Aphid populations are synchronized with citrus growth flush
  • Populations decrease after flush hardens
  • Multivoltine: several generations per year

 

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Natural Enemies

Photo

Ladybird

Photo

Wasp

Photo

Parasitised
Bodies

Photo

Bee/Fly

  • Ladybirds takes approx. 3 weeks to control aphids in the absence of ants

 

Top Check Your Diagnosis Data Sheet Natural Enemies Management
    DAMAGE SYMPTOMS   MONITOR
    LIFE CYCLE   ECONOMIC THRESHOLD
    SEASONAL CYCLE   CONTROL OPTIONS
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Management

 
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