Fruit-spotting bug

Similar to banana-spotting bug (Amblypelta lutescens lutescens).

Scientific name

Amblypelta nitida

Description of adult

Adult bugs are green-brown and about 15mm long. When disturbed, they may fly away, somersault to lower branches or quickly hide on the plant behind fruit or under leaves. The fruit-spotting bug is usually a slightly darker green than the banana-spotting bug.

Immature stages

Fruit-spotting bug eggs are 1.7mm long and somewhat triangular with rounded corners in cross-section, pale green in colour when first laid, turning darker with a slight opalescence as they age. They are laid singly on flowers, fruit or foliage. The bugs pass through 5 nymphal stages before they become adults. The first instar is green and black, and has an ant-like appearance. Later instars are orange-brown or green.

They have prominent antennae and two scent gland openings on the upper surface of the abdomen. Wing buds appear in the third instar. A distinctive feature of the nymphs of both fruit-spotting species is the second last segment of the antenna, which is black and conspicuously flattened. The scent gland openings on the abdomen of A. lutescens are more prominent because they are highlighted with white circles.

Life history

An adult female lays only a few eggs each day, but during its life may lay more than 150  eggs. The eggs hatch in 6–7 days and development from egg to adult averages around 42 days in summer. The insects pass through 3–4 generations a year: 1 in spring, 1 or 2 in summer and 1 in autumn. Adults of the autumn generation survive the winter and begin a new generation when temperatures increase in spring. The adults tend to infest certain groups of trees forming 'hot spots' in orchards.

Distribution

A native insect that occur throughout coastal and sub-coastal areas of Queensland. It is common on the Atherton Tableland but relatively rare on the coast north of Gympie.

Host range

Fruit-spotting bug is a pest of avocados, guavas, macadamia nuts, pecan nuts, lychees, mangoes and many exotic tropical and subtropical tree crops.

Damage

Major, frequent pests in certain areas, especially where orchards are situated close to alternative native or ornamental hosts.

Both adults and nymphs feed by piercing fruit and sucking the juice from the tissue. They insert their long mouthparts into the fruit and in feeding, exude saliva containing enzymes that break down the cells of green fruit such as avocado. This causes deep-set breakdown of significant areas of tissue.

In lychees and longans, the losses result when fruit drops because the bugs have fed on the developing seed.

Brown lesions on the seed and small black 'pin pricks' on the internal white surface of the skin are evidence of bug feeding. In excess of 90% of green fruit may be lost in heavy infestations. Mature fruit is less attractive to the bugs but may be damaged. This fruit does not fall and although the damage may not be detected at harvest, it has little effect on fruit quality.

Control

Examine five green fallen fruit under 20 trees widely spaced throughout the crop. Dissect green fruit that have fallen from the tree immediately after fruit set and for a further month.

Cultural

Be aware of the relationship of natural bug breeding areas to the orchard, and localised damage. If possible, avoid planting trees close to areas of scrub.

Biological

A number of egg parasitoids have been recorded, and assassin bugs and spiders prey upon the bugs.

Chemical

If bug feeding damage is evident, apply a spray and repeat 2–3 weeks later if damage continues. Two sprays should be sufficient, but continue to monitor fallen fruit and respray if necessary. Choose a chemical that is less damaging to parasites and predators.

Chemical registrations and permits

Check the Australian Pesticides and Veterinary Medicines Authority database for chemicals registered or approved under permit to treat this pest on the target crop in your location. Always read the label and observe withholding periods.