There are two similar fruit-spotting species that damage horticultural crops.

The fruit-spotting bug (Amblypelta nitida) is usually a slightly darker green and is less common than the banana-spotting bug (Amblypelta lutescens lutescens).

Both adults and nymphs feed by piercing and sucking. They insert their long mouthparts into plant tissue and cause deep set breakdown. Feeding results in sunken black spots due to tissue damage from introduced enzymes. Banana is not a favourable host for breeding and these pests will only attack commercial bananas if deprived of their normal hosts.

On crops such as cashews, terminal growth can be affected. Damage occurs mainly from October through March and often continues into May. Some varieties are more susceptible than others e.g. the carambola variety Thai Knight is particularly susceptible.

Small fruits, which have just set, are usually shed, while slightly larger fruit may be retained but form a 'dimple' where the damage has occurred.

Injured fruit remaining on the tree are usually unmarketable due to the large lesions that develop around the feeding site. The bugs are more prevalent in coastal orchards, particularly those close to rainforest or scrub. Orchards that are more openly situated have a lower incidence of bugs.

Damage is often confused with that caused by Queensland fruit fly. It is important to diagnose the cause of the damage accurately so that the most appropriate control measure may be applied. Bug damage is more common on the top halves of fruit. Considerable fruit damage can result from the feeding of a relatively small number of bugs. Fruit fly damage can be usually determined by cutting through the entry point and searching for the curved white 3 mm long eggs or for the white-cream carrot shaped maggots of the fruit fly.

Control

Examine five trees at each of six widely spaced locations throughout the crop. Spray when damage is noted.

Apart from positioning the orchard as far as possible from uncleared scrub areas, little can be done to alleviate bug incidence.

Egg parasites are being investigated for biological control of these pests. Green tree ants and assassin bugs can exert considerable control.

Considerable fruit damage may result from the feeding of a relatively small number of bugs that are difficult to detect on the tree. Orchard history and experience dictate the frequency of sprays applied to control the pest. Sprays need to be applied every 2, 3, or 4 weeks depending on the orchard's location and history of attack. Ensure thorough coverage. Mature orchards with touching canopies should be thinned to facilitate spraying as well as to increase the area of fruiting canopy.

The adults are greyish-brown moths with silvery marbling on the forewings; 16 mm in length and about 40 mm across the outstretched wings. The hind-wings are translucent white.

Eggs are laid on the leaves by the night-flying moth in clusters of up to 300 and are covered with a matt of grey-brown hairs from the body of the female. Young larvae are gregarious (hence the name cluster caterpillar) and feed on the lower leaf surface, causing a window effect.

The young larvae are translucent green with black heads. Older larvae are solitary and have conspicuous black triangles in a line along each side of the body. Mature larvae pupate in the soil.

Young larvae feed in close groups and destroy one side of the leaf leaving the opposite side intact.

Damaged areas appear clear at first but quickly turn brown. When larger and more solitary larvae feed on the rolled up 'cigar leaf' a 'shot hole' effect becomes apparent when this leaf expands. On rare occasions large solitary larvae feed on fruit causing superficial scarring.

 

Fruit Piercing Moth (Eudocima sp.)

There are three widely occurring species of fruit piercing moth: Eudocima salaminia, E. fullonia, E. jordani and E. materna. The adult moths are large and stout-bodied, with a wingspan of 100 mm. The forewings can be mainly brown, cream or green. Hind wings are yellow orange, with black patches and spots.

Major and sporadic. Several genera of noctuid moths are fruit piercing but the most damaging are Eudocima fullonia, E. materna, E. jordani andE. salaminia.

Moths feed at night by penetrating the skin of the ripe or ripening fruit with their strong proboscis and sucking the juice. Internal injury consists of a bruised, dry area beneath the skin. Secondary rots develop at the puncture site. Secondary-moth feeders often visit fermenting fruit, taking advantage of the access holes the fruitpiercing moths drill. Early summer to early autumn is the most important period.

Not determined, but would depend on individual fruit value. Nightly inspections with a strong torch are recommended when fruit is nearing maturity. The red eyes of the moths will reflect the light from a torch, aiding detection.

Netting trees or bagging fruits is very effective. Early harvest, where it doesn't jeopardise maturity standards, will help to reduce losses.

Several native parasitic wasps are known but have limited impact during summer.

No satisfactory chemical control measure is known. Hand collection of moths and various traps have had limited success.

Two Spotted Mite(Tetranychus urticae)

Two-spotted mite is a minor, widespread and irregular pest. Mite activity can usually be expected following continuous hot weather.

The mite problem is often induced by excessive use of insecticides against other pests which kills the natural enemies of two-spotted mites, allowing their numbers to increase.

Two-spotted mites form colonies on lower leaf surfaces, especially near the junction of the petiole and leaf blade. Initial symptoms are a bronzing or whitening of the upper leaf surface near the leaf stalk. Fine webbing is visible on the lower leaf surface. Heavy infestations will result in leaf desiccation, leaf drop, and yield loss.

Chemical control: Not cost effective. For current chemical control options

Conservation of natural enemies: Broad-spectrum sprays applied against other pests disrupt activity of natural enemies and induce mite outbreaks.

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The vast majority of the bananas currently grown and consumed were not conventionally bred but are selections made over probably thousands of years from naturally occurring hybrids. Cultivated bananas are very nearly sterile and as a consequence are not propagated from seed but rather through vegetative propagation, primarily suckers as well as more recently micropropagated or tissue cultured bananas. These factors, very old selections, near sterility and vegetative propagation, mean that these bananas have not been genetically improved either for resistance or improved quality and are becoming increasing in affected by serious pests and diseases.

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