Mango leaf gall midge

Mango leaf gall midge is also known as Procontarinia pustulata. It is a relatively newly described species of gall midge in the family Cecidomyiidae.

Adults

• The adult insect is very small, 1–2mm long.
• Similar looking to a mosquito.
• Black eyes, a grey head and antennae, a yellow thorax and abdomen, and tiny grey hairs on its body.

Larvae

• Yellow.
• About 1–1.2mm long.

Pupae

• Not known.

Eggs

• Tiny and laid within the plant tissue.

Galls

• Round, blister-shaped.
• Approximately 2–3mm in diameter and 0.4–0.7mm high.
• Visible on both sides of the leaf.
• When galls are close together they can form larger and more varied shapes in the leaf.
• Can be green, yellow, red or brown to brown-black in colour depending on their age. Young galls may have a yellow halo.
• Different coloured galls can be found on the same leaf.
• When the adult insect leaves the gall, it makes a small exit hole.
• The galls eventually fall out, leaving holes (sometimes called shot holes) in the leaf tissue.

Plant stage and plant parts affected

Mango leaf gall midge affects mango leaves, with tender young leaves and shoots the most susceptible to galling.

Plant damage

• In severe infestations, over 100 galls can be found on a single leaf.
• Infestations can cause leaf deformation, reduced photosynthesis and leaf drop, resulting in reduced fruit production.

Mango scab (caused by a fungus) could be confused with mango leaf gall midge because scab also causes roundish raised leaf spots that can be visible on both sides of the leaves. Scab is generally brown-black, sometimes with a yellow halo, and usually turns grey with age.

Mango leaf gall midge has galls that can be different colours such as green, yellow, red or brown to brown-black (depending on their age) on the same leaf.

If you are unsure or suspect mango leaf gall midge, report it.

Mango leaf gall midge was detected on the eastern Torres Strait Islands in 2006. By 2008 the pest's distribution had expanded across the Torres Strait Islands and had reached the mainland in the remote northern Cape York Peninsula area (within the far northern biosecurity zone 1 (PDD, 333KB)). The pest has not been detected further south, and is not present in Queensland's mango production areas.

Also found in Papua New Guinea.

There are other exotic mango gall midge species of Procontarinia that are not found in Australia.

Mango (Mangifera indica) is the only known host.

• The adult female fly lays her eggs in susceptible mango plant tissue such as new leaves.
• The larva hatch from the egg inside the leaf.
• A distinctive hollow gall forms around the larva.
• Each gall contains a single developing larva.
• Once mature, the larva exits the gall chamber through an exit hole.
• Pupation occurs in soil beneath the infested tree.
• Multiple generations of mango leaf gall midges may be produced each year.

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. Queensland grows 67% of the national crop.

Mango leaf gall midge is a threat to commercial mango production but, due to having only been found recently, its impact is currently unknown. Some mango varieties may be more susceptible to attack than others. Severe infestations may cause leaf deformation and leaf drop resulting in reduced fruit production. Severe infestations may kill younger trees. Older trees may fail to recover from repeated attacks.

Similar types of mango gall midge overseas are reported to cause crop losses ranging from 10–52% in India, 30–40% in Indonesia and Papua New Guinea, and 40–50% in the Philippines and South East Asia.

If mango leaf gall midge were to establish in a mango production area, other states and territories or other countries may restrict import of mangoes.

Mangoes are common backyard trees in Queensland, so home gardeners would also be affected.

Adult mango gall midges can fly and spread naturally in localised areas from mango tree to mango tree. Their spread may be enhanced by strong winds. There are large distances between host mango trees on Cape York Peninsula which helps limit natural spread of this pest.

Mango leaf gall midge can also be spread by human-assisted movement of infested plant material and in infested soil (pest carriers).

The Far northern biosecurity zones 1 and 2 (PDF, 333KB) have been established to restrict the movement of far northern pests, such as mango leaf gall midge, and pest carriers to the rest of Queensland.

Inspect mango trees for misshapen leaves and increased leaf fall. Examine the leaves for the presence of blister-shaped galls and shot-holes. Inspect stems, fruit and flowers for similar symptoms.

If you find evidence of mango leaf gall midge outside of the far northern biosecurity zone 1, you must report the incident as soon as possible to Biosecurity Queensland on 13 25 23.

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

The far northern biosecurity zones (PDF, 333KB) have been established to prevent the spread of far northern pests like mango leaf gall midge.

It is illegal to move:

• a far northern pest such as mango leaf gall midge
• far northern pest carriers, such as mango plants, mango fruit, and soil or other growing mediums in which a mango plant has been grown
  • from far northern biosecurity zone 1 to a place outside of that zone
  • from far northern biosecurity zone 2 to a place outside that zone unless it is into far northern biosecurity zone 1.

Far northern pests and their carrier may be moved using a biosecurity instrument permit.

For information about biosecurity instrument permits, call the Customer Service Centre on 13 25 23 or email qld.plantquarantine@daf.qld.gov.au.