Lightbrown apple moth - Natural enemies and diseases

Lightbrown apple moth in New Zealand is attacked by a range of parasites and by predators and diseases, which make a major contribution to control, particularly if broad-spectrum insecticides are avoided. With the introduction of selective insect growth regulator chemicals and organic production methods for leafroller control, these natural enemies are now playing a greater part in leafroller management in orchards. Biological control has been supplemented by the introduction of natural enemies from Australia, where lightbrown apple moth is a native.

The greatest mortality occurs to young larvae hatching from egg batches and before they have settled (spun shelters) on the leaves. These losses are probably due to a number of predators, including spiders and predatory bugs, as occurs in Australia. The most widespread and abundant parasitoid is Dolichogenidea tasmanica, a braconid parasitic wasp about 2-3 mm long, which attacks young (1st and 2nd stage) lightbrown apple moth caterpillars. From 19 to 50% of the larvae may be parasitised in lightbrown apple populations in apple orchards. There are at least four closely related species of Dolichogenidea obtained from leafrollers in New Zealand, including Dolichogenidea carposinae and Dolichogenidea sp. 3, formerly referred to as Apanteles sicarius.

Other natural enemies and diseases include (this is not an exhaustive list):

Ancistrocerus gazella - this predatory eumenid wasp paralyses and collects caterpillars of lightbrown apple moth. The caterpillars are stored in the nest cells as food for the wasp larvae.

Anystis baccarum (L.) - a bright red or orange predatory mite (whirligig mite) which feeds on eggs and young larvae.

Birds - a number of bird species feed on the larval, pupal, and adult stages, including the silvereye, Zosterops lateralis.

Brachymeria phya (Walker) and Brachymeria teuta (Walker) - chalcid wasps introduced from Australia. These pupal parasitoids are encountered only occasionally.

Diadegma sp. - ichneumonid wasps which attack a small percentage of the caterpillars of lightbrown apple moth.

Entomophthora sp. - a fungus which causes sporadic outbreaks of disease in caterpillars during favourable wet weather conditions, especially in late summer.

Eugregarine parasites - these protozoans occur in the gut, and sometimes the body cavity, of lightbrown apple moth caterpillars. They tend to delay larval maturation but do not appear to cause death.

Eulophid wasps - two genera of these parasitoids (Sympiesis sp. and Zealachertus sp.) attack a small percentage of the caterpillars of leafrollers. Several wasps are produced from each caterpillar.

Eupsenella sp. - bethylid wasps which attack the 3rd and 4th stage caterpillars.

Forficula auricularia L. - the common earwig that feeds on young caterpillars is considered an important predator of lightbrown apple moth in Australia.

Goniozus jacintae, a bethylid wasp introduced from Australia. This commonly attacks the 3rd and 4th stage caterpillars. Goniozus sp. was introduced in the period 1967-1969 and examination of the voucher specimens has shown that this included G. jacintae which was already present in the country. G. jacintae was probably introduced in 1922 and may have been self-introduced with lightbrown apple moth from Australia.

Glabridorsum stokesii (Cameron) - an Australian species introduced to New Zealand in the 1970s. It is now well established in the North and South Islands. This ichneumonid wasp parasitises the pupal stage of lightbrown apple moth and Oriental fruit moth.

Glyptapanteles demeter (Wilkinson) - a braconid wasp (about 2 mm long) which frequently parasitises 1st and 2nd stage caterpillars.

Nematodes - parasitic nematodes have been reported to occur in larvae of lightbrown apple moth.

Nucleopolyhedrosis virus - a disease which kills the larvae. This is widespread in orchard soils and at low levels in natural populations. It has been tested as a spray for control of lightbrown apple moth, with some success.

Orius vicinus (Ribault) - a predatory bug which feeds on eggs and young larvae.

Pales funesta (Hutton) and Pales feredayi (Hutton) - minor parasitic tachinid flies which attack caterpillars of lightbrown apple moth, and emerge later from the pupal stage.

Pentatomid bugs - including Oechalia schellenbergii (Guerin Meneville) and Cermatulus nasalis (Westwood). These predatory bugs feed on caterpillars of lightbrown apple moth.

Sejanus albisignata (Knight) - a predatory bug which feeds on eggs and young larvae. The nymphs of the bug are brick red in colour while the adult is black with two characteristic white flecks, one each side of the wings midway down the back.

Spiders - a range of species feed on the caterpillar stages and adults. Spiders are considered important predators of lightbrown apple moth in Australia, especially the theridiid Achaearanea veruculata, which also occurs in New Zealand. Serological tests with spiders in Australia have shown that 53% of Thomisidae, 46% of Theridiidae, and 41% of Salticidae preyed on lightbrown apple moth larvae. All these families of spiders are well represented in New Zealand. Spiders encountered in Auckland apple orchards include Achaearanea veruculata, Ixeuticus martius (Amaurobiidae), Trite planiceps and Trite sp. (Salticidae), several Diaea spp. (Thomisidae) and Clubiona sp. (Clubionidae). Laboratory tests demonstrated that all these spiders would feed on leafroller caterpillars. Spiders of the families Theridiidae, Oxyopidae, Clubionidae, and Epeiridae were recorded as predators of lightbrown apple moth in Canterbury.

Trichogrammatids - minute parasitic wasps which attack the eggs causing them to turn black. Three species have been identified: Trichogramma sp., Trichogramma (Trichogrammanza) funiculatum and Trichogrammatoidea bactrae fumata.

Trigonospila brevifacies (Hardy) - a parasitic tachninid fly introduced from Australia in the 1970s. This fly is well established in New Zealand throughout the North Island and has been recovered in the north of the South Island. It lays eggs (usually singly) on lightbrown apple moth caterpillars and later forms a fly puparium inside the lightbrown apple moth pupa.

Vespula spp. - the common and german wasps have been recorded as predators of lightbrown apple moth larvae.

Xanthopimpla rhopaloceros Kreiger - an ichneumonid wasp introduced from Australia in the 1970s and widespread throughout the North Island. It has also been recovered in Nelson. It parasitises lightbrown apple moth pupae.