Oriental Fruit Moth

Description

Adults are grey – brown and small (6 – 7 mm), with a wingspan of 11 -14 mm. Eggs are laid on the underside of leaves and are grey – white in colour and 0.5 – 0.8 mm in length. Larvae are 10 – 14 mm in length, which are initially white with a black head, turning pink - red as they mature. Pupae are 6 – 7 mm long, yellowish to brown in colour when immature, becoming dark red at maturity. Pupation occurs in sheltered positions such as under bark or leaves. Oriental fruit moths survive winter as dormant larvae under bark, in tree cracks or wounds and in tree debris, preferring to hibernate in older trees with rough bark, rather than smooth barked trees.

Larvae feed on the shoots and tips of young, green actively growing plants, causing them to appear distorted and to dieback. During summer, larvae will selectively bore into mature fruit, however if numbers are high enough, immature fruit can also be affected. Tunnels are formed in the fruit making it unmarketable, but this also provides an entry point for bacteria to enter, often causing fruit to decay. Damage to fruit from OFM is easily distinguishable from mechanical damage, due to the presence of frass which is excreted by the larvae. Oriental fruit moths are favoured by seasons where there is vigorous spring growth.

Control

A sustainable approach to managing OFM should incorporate cultural and chemical methods. Growers should ensure orchards are maintained to reduce limb breakage and vigour as OFM prefer to hibernate in cracks of broken limbs or succulent shoots. Well maintained orchards also allow good spray coverage. Prunings and any unharvested fruit should be removed prior to moth emergence to reduce the likelihood of OFM populations building up. Old orchards which have been bulldozed, can harbour OFM and should be burnt to ensure this source of infestation is eliminated.

Oriental fruit moths are mobile and can fly long distances, therefore engaging with neighbours to ensure they are managing their orchards and actively controlling OFM is important. Growers should be vigilant in disinfecting fruit bins, particularly if they have come from another orchard, as OFM can hibernate in cracks.

Monitoring orchards for the presence of OFM should commence when moth flights begin. Pheromone traps emit pheromones, which attract male moths and are useful at indicating population levels within an orchard. Lure pots attract both male and female moths, however they have a low attraction rate compared to pheromone traps and therefore require a higher number of traps to be effective. Both methods may assist growers to make timely control measures.

Mating disruption is another method used, where an attractant usually released by female moths is emitted into an orchard by dispensers. As a result, male moths become disorientated and cannot find females to mate, reducing the likelihood of eggs being fertilised and therefore keeping populations low.

Trees should be monitored for symptoms such as wilting growth, which can indicate the presence of OFM. Once threshold levels are reached, an application with an insecticide may be required. Vayego® is registered for the control of OFM in stone fruit and applications should commence post petal fall, when predictive models from local agencies indicate egg hatch of a generational peak. Calypso® is also a proven product that is a cost effective solution registered for the control of OFM in pome and stone fruit.

References

Australian Government (2010), ‘Final import risk analysis report for fresh apple fruit from the People’s Republic of China’, page 121, Current version final clean copy 100629.doc (agriculture.gov.au)

Hetherington, S (2005), ‘Integrated pest and disease management for Australian Summerfruit’, pages 57 -62, Integrated pest and disease management for Australian summerfruit (nsw.gov.au)

Jenkins, C (1952), ‘Oriental Fruit Moth’, Journal of the Department of Agriculture Western Australia, Series 3, Department of Primary Industries and Regional Development (DPIRD), Oriental fruit moth (agric.wa.gov.au)

Ullio, L (2009), ‘Common insect pests of nectarines’, NSW Government, Industry and Investment, Primefact 889, Common insect pests of nectarines (nsw.gov.au)