Cocoa pod borer

Alert

Have you seen Cocoa pod borer?

Be on the lookout and report signs to Biosecurity Queensland on 13 25 23 or contact the Exotic Plant Pest Hotline on 1800 084 881.

Early detection and reporting are key elements in controlling Cocoa pod borer.

The cocoa pod borer (Conopomorpha cramerella) can cause significant yield loss in cocoa and rambutans.

The pest was found on a cocoa plantation in Far North Queensland in 2011 and has been eradicated.

Scientific name

Conopomorpha cramerella

Other names

  • Cacao moth
  • Cocoa moth
  • Javanese cocoa moth
  • Rambutan borer
  • Ram-ram borer

Description

Adults

  • The adult is a mosquito-sized moth, approximately 5–7mm long, belonging to the family Gracillariidae.
  • Moths are brown with bright yellow patches at the tips of the forewings, and have long antennae that are swept backwards when at rest.
  • Moths are active during the early evening and night, resting on the underside of branches and leaves during the day.

Larvae

  • Larvae (i.e. caterpillars) are translucent to creamy white or greenish.
  • 1–10mm long depending on their age.

Pupae

  • Oval shaped cocoon that is formed in a cocoa pod crevice or green dried leaves or other debris.

Eggs

  • Tiny, barely visible to the naked eye and are coloured yellow to orange.

Plant stage and plant parts affected

  • Young, green cocoa pods are particularly susceptible to attack.

Damage to cocoa

  • Larvae feed inside cocoa pods on the material that surrounds the individual cocoa seeds.
  • The larval feeding causes the seeds to stick together, which produces undersized seeds and poor-quality cocoa beans.
  • The fruit pulp becomes hard and the normal fermentation process used to produce the cocoa flavour can be adversely affected.
  • Other symptoms of damage include entry and exit holes on the husk created by tunnelling larvae, and overall premature or uneven ripening of pods.

Damage to rambutan

  • The pest tunnels into leaves, stems and occasionally the fruit, making it unmarketable.

Distribution

Known to occur in Brunei, China, India, Indonesia, Malaysia, Papua New Guinea, the Philippines, Samoa, Sri Lanka, Taiwan and Thailand.

Hosts

The main commercial hosts are cocoa (Theobroma cacao) and rambutan (Nephelium lappaceum).

Other reported hosts include:

  • kola nut (Cola spp.)
  • nam nam (Cynometra cauliflora)
  • wrinkle pod mangrove (Cynometra iripa)
  • langsat (Lansium domesticum)
  • pulusan (Nephelium mutabile)
  • Fiji longan
  • Pacific lychee
  • taun
  • tava
  • kasai (Pometia pinnata)
  • wild rambutan (Xerospermum spp.).

Life cycle

  • The adult female moth generally lays eggs on the surface of cocoa pods that are 2–6 weeks from the first signs of yellowing or on other host fruit.
  • Larvae hatch from the eggs after approximately 3 days (temperature dependant), and tunnel through the husk into the pulp around the beans, then into the placenta that holds the beans together.
  • Larvae moult as they grow. There are 4–6 instars (stages of larval growth).
  • The larvae exit the pod through holes made in the husk wall after approximately 2–3 weeks.
  • Larvae spin a cocoon and pupate (change into an adult moth) either in a crevice on the fruit surface, or on the ground amongst dried leaves, weeds, or other ground litter.
  • Adults emerge from the cocoons about 1 week later.
  • They are poor fliers, and are most active at night when they mate and lay eggs.
  • Adults are short-lived. While they can survive up to 30 days, about 1 week is the average lifespan.
  • In cocoa, fruit is required to complete the life cycle. However, in rambutan, there are records of the pest also damaging leaves and young stems.

Impacts

Cocoa production is a boutique industry in Far North Queensland. Australian rambutan production is estimated to be around 750 tonnes with a gross value of $6 million annually, of which 75% is grown in Far North Queensland. Both industries have the potential to expand.

Cocoa pod borer damages cocoa and rambutan fruit, causing significant yield loss. In cocoa, fruit damage makes the processing of cocoa pods difficult and reduces cocoa bean quality. In rambutan, the pest tunnels into leaves, stems and occasionally fruit, making it unmarketable. Growers would experience increased pest control costs and cocoa pod borer could affect market access for rambutans.

Backyard growers would also suffer cocoa and rambutan fruit loss due to cocoa pod borer.

How it is spread

People moving cocoa pods or other infested host fruit, or plant material infested with cocoa pod borer eggs, pupae or moths, could spread cocoa pod borer to new areas and even introduce this pest into Australia.

The Australian Government closely regulates approved imports of plant material and monitors for illegal plant movement to prevent the introduction of exotic plant pests.

The adult moths are poor fliers, so generally spread in infested areas is believed to be slow.

Monitoring and action

Monitor cocoa pods for uneven ripening and/or for tiny borer holes (though these are very small and hard to see). If detected, cut the pods open and examine them for the presence of borer caterpillars and/or internal borer damage within the pod.

It is also effective to examine pods for internal damage and borers during cocoa pod splitting and processing.

Examine fallen rambutan fruit for tiny borer holes. If detected, cut open the fruit to look for larvae (caterpillars).

If detected, report immediately to Biosecurity Queensland.

Control

Cocoa pod borer was eradicated from Queensland by disrupting the life cycle of the pest. This included removing host material, applying insecticides, altering agronomic practices and putting strict biosecurity measures in place on the infested property.

A district wide area freedom surveillance program was completed to prove the pest is no longer present in Queensland. Based on available literature, it is believed that Australia is the only country to have achieved national eradication of the pest.

Legal requirements

If you think you have found cocoa pod borer, you must take all reasonable and practical steps under your control to minimise any associated risks. This is called a general biosecurity obligation (GBO).