Mango pulp weevil

Mango pulp weevil is a small insect also known as Sternochaetus frigidus.

Adults

• Small insects with long snouts.
• About 6-9mm long, thick bodied and mottled brown in colour.

Larvae

• Plump, whitish, legless grubs, with a well-defined brown to black head.
• They have 5 growth stages (instars).

Pupae

• Up to 10mm in length, and vary from white to pale red in colour.

Eggs

• The tiny eggs are about 0.6 x 0.3mm, roughly elliptical and white to pale yellow in colour.

Plant stage and plant parts affected

Flowering and fruiting mango trees are affected as mango pulp weevil predominantly feed on fruit.

Plant damage

Mango pulp weevil causes premature fruit drop and loss of marketable fruit. Infested fruit may have no outward visible signs that the pest is present within, until the adult weevil tunnels its way out of the fruit.

Mango pulp weevil looks very similar to mango seed weevil which is already present is some parts of Queensland. A trained entomologist is required to tell them apart. The most obvious difference between them is that mango seed weevil feeds on and in the mango seed, while mango pulp weevil feeds inside the flesh, or pulp, of the fruit.

If you suspect mango pulp weevil, don't hesitate to report it.

Mango pulp weevil is found in South Asia (north-east India and Bangladesh) and South-East Asia (Brunei Darussalam, Indonesia, Malaysia, Myanmar, Papua New Guinea, the Philippines, Singapore and Thailand).

It has not been found in Australia.

Mango (Mangifera indica)

• The larvae hatch from eggs laid on fruit and tunnel through the flesh forming a chamber next to the seed.
• From there each larva continues to tunnel through the mango flesh leaving brown granular faeces behind.
• The larva eventually develops into a pupa which remains in a chamber, until it develops into the adult weevil.
• The adult weevil emerges from the fruit by boring a hole out through the mango skin.
• Mango pulp weevil has been reported to produce 1 generation per year, with the species completing the egg to adult life cycle in 35–53 days.
• Adult weevils can survive inside fallen mango fruit and can overwinter under loose bark or in crevices in the tree trunk, or in leaf litter and other fallen plant material.

Mangoes are an important crop in Queensland. The Australian mango industry produces about 60,000 tonnes of fruit annually, providing a gross value of production at the farm gate of about $180 million per year. The majority (67%) of these mangoes are grown in Queensland (sources: Australian Mangoes, Plant Health Australia).

Mango pulp weevil has been reported to have a high economic impact on Asian mango industries because it causes premature fruit drop and loss of marketable fruit. If mango pulp weevil established in Australia, domestic and export market access could be disrupted, and costly control measures may be required.

Home gardeners with mango trees would also be affected as the larvae infest mango fruit making them unsuitable for people to eat.

Mango pulp weevil completes much of its life cycle within mango fruit, and infested fruit can look normal on the outside. This pest could spread long distances by people moving infested fruit or plant material. The Australian Government closely regulates approved imports and monitors for illegal plant movement to prevent exotic pest entry to Australia.

Where mango pulp weevil is known to occur, orchard infestations tend to be localised. Adult weevils can fly, but generally do not spread far after they emerge from infested fruit.

Look for mango pulp weevil during the fruiting season.

Be suspicious if there is more fruit drop than usual.

You will need to cut fruit open to expose the inside of the fruit and seed to look for mango pulp weevil. Look for burrowing damage, insect faeces, larvae, pupae and adult weevils in the fruit flesh.

Mango pulp weevils will be found in the mango fruit flesh whereas the mango seed weevils tunnel through the flesh to get to the seed, which is their main food and where they cause most damage.

If you suspect mango pulp weevil, contact Biosecurity Queensland on 13 25 23, and they will advise how to take action.

• Protect your farm from emergency plant pests
• Understand good farm biosecurity
• Visit the farm biosecurity website

Mango pulp weevil is prohibited matter under the Biosecurity Act 2014.

Report suspected mango pulp weevil to Biosecurity Queensland immediately on 13 25 23 or contact the Exotic Plant Pest Hotline on 1800 084 881.

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