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).
Amblypelta lutescens lutescens
|Description of adult|
Adult bugs are yellow-green-brown and about 15 mm long. When 'disturbed', they may fly away, somersault to lower branches or quickly hide on the plant behind fruit or under leaves.
The eggs are 1.7 mm long and somewhat triangular with rounded corners. They are pale green in colour with a slight opalescence, and they are laid singly on flowers, fruit or foliage.
There are five nymphal stages before the adult. Early stages are ant-like, orange-brown with prominent antennae and have two scent gland openings on the upper surface of the abdomen. Later stages are greener and have wingbuds. The nymphs of both species have antennae with a black and conspicuously flattened second last joint.
Banana-spotting bug nymphs are a lighter red than the fruit-spotting bug and have distinctive light red stippling surrounding the pair of large black spots on the abdomen. The scent gland openings on the abdomen are more prominent because they are ringed with white.
An adult female lays only a few eggs each day, but during its life may lay more than 150 eggs. They hatch in 6-7 days and their development from egg to adult averages 34-38 days in summer. The insects pass through 3-4 generations a year: one in spring, one or two in summer and one in autumn. Adults of the autumn generation survive the winter and begin a new generation when temperatures increase in spring. In north Queensland breeding is continuous.
This native species occurs throughout coastal and sub-coastal areas. During the 1980's banana-spotting bug became very common in southern Queensland, causing extensive damage to many fruits.
The banana-spotting bug damages avocados, bananas, cashews, custard apples, macadamia nuts, papaws, guavas, lychees, passionfruit, pecans, citrus, the exotic tropical tree crops grown along the coastal strip and on the fringing ranges and tablelands from Brisbane to Cape York. Wild hosts include umbrella tree, cockie apple, corky passion vine, white cedar, rough leafed fig, and malay rubber vine.
Major and frequent.
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.
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.
Chemical registrations and permits
Check the Australian Pesticides & Veterinary Medicines Authority chemical database and permit database for chemicals registered or approved under permit to treat this pest on the target crop in your State/location. Always read the label. Always observe withholding periods.