Integrated Pest Management

BOLLWORM
LEPIDOPTERA: NOCTUIDAE: Helicoverpa armigera

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    DAMAGE SYMPTOMS   MONITOR
    LIFE CYCLE   ECONOMIC THRESHOLD
    SEASONAL CYCLE   CONTROL OPTIONS
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Identification

Photo

Adults have large wings covered in scales.
The pest life stage is the caterpillars.
Caterpillars have chewing mouthparts and feed on plants.

 

Check Your Diagnosis

 

Photo

 

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    DAMAGE SYMPTOMS   MONITOR
    LIFE CYCLE   ECONOMIC THRESHOLD
    SEASONAL CYCLE   CONTROL OPTIONS
        CHECK POINTS

 

Data Sheet

Damage Symptoms

on fruit

PHOTO

on leaves

 

on blossom

Photo

on twigs

 

1. On Fruit

Feeding damage Want to know more?
  • Feeds on fruitlets and blossoms.
  • Seldom seen on larger fruit
  • Injury sustained on fruitlets, grows with the fruit. Severe injury to fruit must be culled.

2. On Leaves

Never observed in Vaalharts

3. On Blossoms

Feeding damage Want to know more?
  • Feeds on blossoms and small fruitlets
  • Now is the time to take action against bollworm infestations

4. On Twigs

None

Life Cycle

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)
   

Diagram of life cycle

Photos of life cycle

Complete metamorphosis: moth egg larvae pupa = 150 days

Larvae is the caterpillars that attack the citrus blossoms

  Must know Extra info
EGGS
  • Eggs are laid singly on blossoms or on young leaves.
  • Freshly laid eggs are whitish-yellow but turn darker as the larva grows.
 
LARVA
  • Six instars
  • Drops to the soil to pupate.
  • Larvae are cannibalistic
  • Extremely active
  • Fourth and fifth instars look like the adult with three longitudinal bands
PUPA
  • overwinter in soil
  • Cold spells beneath freezing can kill the pupae of the bollworm
  • Temperature plays a major role in emergence of the moths
MOTHS
  • Males are pale olive gray with reddish brown antennae. Body length = 16-18 mm
  • Females are darker in color than the males
  • Moths feed on nectar
  • Moths are attracted to light traps
  • Males live 8 days and females 11 days
  • Moths fly at night.
  • The females are attracted to the scent and color of blossoms
  • First flying moths are mostly from the overwintering pupae
  • First flights are in August
  • Egg laying in September and emergence of larvae in mid-September to coincide with blossoms

 

Seasonal Cycle in Vaalharts

Graph
Bollworm is only a pest in spring in the Vaalharts region

The reason for the short infestation time is that the whole region has a uniform and short blossoming period for all varieties of citrus

The first emergence of bollworm is mid September

The infestation length can be from a week to a month, depending on the level of the pest population

  • Multivoltine: several generations per year

 

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

 

Natural Enemies

Photo Photo Photo Photo

 

 

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

Management

 
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