Light brown apple moth

Description

Adult moths are bell shaped, light brown and about 10 mm in length. Females have a wingspan of 18 – 20 mm, while males are much smaller. Females are distinguishable by the presence of a dark spot in the centre of their folded wings, whilst males have a dark band across their folded wings. Being weak flyers, LBAM infestations usually come from background populations within the orchard, or move in from nearby infected plants.

Light brown apple moth eggs are laid onto the upper leaf surface or near soft tissue, such as growing points. Eggs are pale green and laid in flat overlapping masses, consisting of 25 - 50 eggs, hatching within 1 – 2 weeks. Small (1 mm), pale yellow larvae emerge and once mature, larvae can reach 18 mm in length and appear green with fine hairs over their body. Larvae go through six stages of growth before maturity, progressing into pupae which are green – brown, emerging as moths a few weeks later.

Young larvae which hatch from eggs laid in early autumn, survive winter on ground cover plants, fallen leaves or under bark. The larvae continue to feed throughout winter completing their development, transforming into pupae during early spring and summer, before emerging as adult moths. Depending on temperature, there can be three or four generations each year.

Light brown apple moth larvae feed on fruit, leaves and flower buds. In oranges, they cause a halo type scar around the stem end and fruit drop. While in apples, damage is often seen as surface damage to the fruit, which can cause a layer of corky tissue to form as the fruit matures, making it unmarketable. Stings, which are small and round are caused by larvae biting through the fruit. Internal damage occurs when young larvae enter via the calyx, although this is rare. Young larvae also feed on leaf tissue producing windows, however this rarely causes any economic damage.

Control

Light brown apple moths can be effectively managed by combining cultural, biological and chemical control methods. The use of selective insecticides supports natural predator populations, such as spiders, lacewings, earwigs and parasitoids. Growers should limit the use of broad-spectrum insecticides where possible to preserve these natural predator populations.

Light brown apple moths are selective where they feed, preferring to feed in sheltered positions. Therefore, thinning fruit can help reduce damage and assists in better spray coverage. Weeds, such as dock and capeweed, are sources of food and shelter during winter, therefore controlling them will help reduce LBAM populations.

Mating disruption can be used to effectively manage LBAM. It works by flooding the target zone with synthetic female pheromones released from dispensers, which effectively decreases the success rate of males finding local females and therefore reduces the production of viable eggs. For best results, dispensers should be put out during August, and a large area needs to be treated for effective results.

Early season monitoring allows growers to manage populations prior to crop losses occurring. Pheromone based traps are commonly used to lure male moths, which generally indicates the arrival of female moths. If high numbers of moths are consistently being trapped, fruit and growing tips should be monitored for the presence of larvae or pupae.

If LBAM is detected, an application of an insecticide may be necessary. Vayego® is a novel new insecticide with efficacy on multiple life stages, has long residual activity and is proven to reduce fruit damage in pome fruit. Vayego® is registered for the control of LBAM in pome fruit and can be applied up to three times if required.

References

Department of Agriculture and Primary Industries and Regional Development (DPIRD) (2020), ‘Epiphyas fruit moths in Western Australia – light brown apple moth and western fruit moth’, Agriculture and Food, Epiphyas fruit moths in Western Australia – light brown apple moth and 'western fruit moth' | Agriculture and Food

Hertherington, S and Munroe, A (2009), ‘Integrated pest management for Australian apples and pears’, The State of New South Wales, Industry and Investment NSW, Apple and Pear Limited p 73 -78, https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0009/321201/ipm-for-australian-apples-and-pears-complete.pdf

Mo, J (2006), ‘Light brown apple moth in citrus’, NSW Department of Primary Industries, Primefact 216, Light brown apple moth in citrus (nsw.gov.au)