A single, adult Fall armyworm (FAW,
Spodoptera frugiperda) was detected in April 2021 in a surveillance trap near Wynyard in north-west Tasmania. This is the first time this pest has been detected in Tasmania.
FAW is an invasive tropical and subtropical pest native to the American tropics. It has rapidly spread across Australia following initial detections and establishment in the north of the country. It was first detected in far north Queensland in January 2020 and was subsequently detected in northern Western Australia and the Northern Territory, making its way south into New South Wales later in 2020 and being detected in Victoria during December 2020.
FAW is reported to feed on more than 350 plant species, including maize, cotton, rice, sorghum, sugarcane, wheat, and vegetable and fruit crops, and has caused significant economic losses in tropical and subtropical regions overseas.
As a precautionary measure, in early 2020, Biosecurity Tasmania declared FAW an Unwanted Quarantine Pest under the Plant Quarantine Act 1997. This means that in the event it is intercepted in traded plants or plant products at the border, regulatory intervention can be undertaken.
What is the risk for Tasmania?
FAW is native to tropical and subtropical regions of the Americas and is most likely found in warm, moist regions where it thrives. So why has it been found in cool temperate Tasmania?
The reason why FAW has spread so quickly from northern Australia is due to its ability to disperse long distances in wind currents. Due to this ability, it is likely to migrate into Tasmania and other southern states from the warmer northern states, particularly during the warmer months. However, such migrations into Tasmania are likely to be seasonal and any populations that are initiated during the warmer months are likely to die back in the cooler months. As populations increase interstate, incidences of FAW in Tasmania are also likely to increase due to increased migration.
However, due to its preference for warmer temperatures (see climate suitability map below), it is unlikely to thrive or establish permanent populations in the cool temperate Tasmanian climate.
FAW larvae can affect leaves, shoots, stems and fruit. Plants of different ages, seedlings to mature plants, can be affected.
FAW larvae initially feed on leaves, creating pinholes and windows in leaf tissue, and giving leaf margins a tattered appearance. In grass-like plants, they often feed within the leaf whorl (where leaves radiate from or wrap around the stem or stalk). Insect frass (droppings) is a sign that larvae are present. FAW larvae can also eat buds and tunnel into and feed on fruit. Larger larvae can cut plants off at the base.
Eggs are usually laid on the under surface of leaves in clustered masses of 100-200, covered with a ‘felt like’ layer of scales. The eggs are pale yellow.
FAW larvae are between 6 mm (early stages) and 36 mm (late stages) in length, green or brown with black lines along the body and around the spiracles. They have numerous black hairs.
Adults moths are 32-40 mm in length from wing tip to wing tip, with a brown or grey forewing and a white hind wing. The wings of male fall armyworm moths are more patterned than those of the females. Males also have a distinct white spot on each of their forewings.
FAW larvae and adults, and the plant damage caused by FAW, can be confused with a number of armyworm species that are present in Tasmania. Entomologists at Biosecurity Tasmania will identify any suspected FAW specimens at no cost. Alternatively, for those who are keen to improve their insect identification skills, links to excellent identification resources are provided in the further information section below.
Biosecurity Tasmania have two light traps at Stony Rise and Prospect which have been monitored for FAW since the original incursion into northern Australia. Following the detection in Victoria in December 2020, Biosecurity Tasmania and Serve-Ag established 13 FAW specific bucket pheromone traps across Northern Tasmania.
To enhance surveillance, Biosecurity Tasmania are encouraging growers and members of the public to help detect FAW. The most likely way of detecting FAW is looking for damage and late stage larvae in infested host plants. There are over 350 host plants including economically important cultivated crops such as maize, corn, and wheat and other vegetable and fruit crops. A full list of known hosts can be found here
Any suspect specimens should be submitted to Biosecurity Tasmania.
Sample collection and submission
- Collect late stage larvae (larger larvae) with host plant material (preferred). Adult moths or eggs can be collected if available.
- Larvae and host plant material can be placed in a zip lock sandwich bag (securely locked). If applicable, collect larvae on each host plant into a different zip lock bag. If collected, adult moths should be placed in an appropriately sized sturdy container (e.g. plastic sample container from chemist or small jar) and immediately placed in the freezer. A piece of crumpled paper towel can be included in the container. This prevents moths losing scales which are important for identification purposes.
- Write on the front of the bag or container in permanent black marker the name of the host plant, collection date, collection location address and the name of the collector.
Place all of the sample bags inside one larger zip lock bag (to ensure all insects are contained) and place inside a padded envelope or similar with a completed sample submission form:
Plant Diagnostic Services - Sample Submission Form (454Kb)
Forward samples to the nearest Biosecurity Tasmania entomology laboratory or seek further sample collection and submission advice from Plant Diagnostic Services:
South: New Town Laboratories, 13 St Johns Avenue, New Town 7008
North: Mt Pleasant Laboratories, 165 Westbury Road, Prospect 7250
North-West: Stony Rise Government Offices, Rundle Road, Devonport 7310
There is a large amount of information on FAW available online. The following links provide excellent information on FAW identification:
- The NSW Department of Primary Industries have made a series of YouTube webinars covering (1) biology, hosts and damage, (2) diagnostics and identification, (3) surveillance, control options, and a Q&A session. The webinars can be accessed directly here:
- Australian Department of Primary Industries and Regional Development fall armyworm webpage (includes a presentation on fall armyworm identification):