Melon thrips

Have you seen melon thrips symptoms?

The melon thrips has a restricted distribution in Queensland. It has been detected in a number of areas in coastal North and South East Queensland. (See the quarantine restriction section below for details.)

Be on the lookout for melon thrips. If you see symptoms outside these areas, report them to us on 13 25 23 immediately.

Melon Thrips

Figure 1: Melon thrips

Melon thrips damage to eggfruit

Figure 2: Melon thrips damage to eggfruit

General information

Melon thrips (Thrips palmi) is a pest of fruit and vegetables in South East Asia, Japan, Florida and the Caribbean. It can stunt susceptible plants and deform fruits when its normal biological control is disturbed.

It was detected in the Northern Territory in 1989 and Queensland in 1993, and has since been found in various parts of Queensland. Several states have restrictions for imports of host produce from within 100 km of outbreaks of the pest.

What does it look like?

The melon thrips is a small (1.3 mm long), cigar-shaped insect (see Figure 1) that can barely be seen with the naked eye. The pest is pale green to orange and found mostly on the undersides of leaves. It can also be found on fruit and in flowers. On cucurbits, the pest will mostly be found towards the tip of a runner.

Because the melon thrips needs to be properly managed to minimise damage, it is important for the Department to identify the pest. The thrips is a very small insect that needs a specialist for correct identification. If the pest is not correctly identified, incorrect chemicals may be used, which can worsen the problem, leading to crop loss and increasing the chances of melon thrips spreading.

Damage

The melon thrips damages plants by killing surface cells with its piercing and sucking mouthparts during feeding. At low levels, there may be no visible sign of damage. In high numbers, melon thrips produce silvering, yellowing and bronzing of affected areas. Leaves may crinkle and die; growing tips may become stunted, discoloured and deformed; and fruits may abort or develop scar tissue (see Figure 2). The overall effect is a loss of plant vigour and a reduction in marketable produce.

Which crops or plants are most seriously affected?

The melon thrips can affect a variety of fruits, vegetables, ornamental plants and weeds. It is particularly damaging to eggplant, capsicum, chilli, rockmelon, cucumber, squash, zucchini, and French bean. Weed hosts include pigweed, amaranthus, gomphrena and potato weed, as well as a variety of cucurbit and solanum family plants, such as the tall weed shrub, devil's fig (Solanum torvum).

Management

Although the melon thrips is difficult to control, growers in the Northern Territory and Queensland have successfully managed the pest through a variety of measures including using plastic mulch (preferably silver), controlling weeds that are alternative hosts, breaking production cycles of susceptible crops and using windbreaks.

In the past, the overuse of insecticides has increased the problem, probably by killing natural enemies.

Quarantine Restrictions

There are no quarantine restrictions for movement of melon thrips hosts within Queensland. However, South Australia, Western Australia and the Northern Territory restrict the introduction of host crops and plants from within a 100 km radius of a detection of the pest.

Inspection for pest freedom and methyl bromide fumigation are two procedures available for meeting the restrictions, which now apply to most horticultural production areas in Queensland. See restricted area maps for coastal North Queensland and South Queensland.

There may be other pests of quarantine concern and businesses sending restricted items interstate must first contact the destination state or territory department of agriculture or primary industries for the current entry conditions.

Last updated 03 September 2012