FAW larvae have a pale yellow inverted ‘Y’ on forehead. Image: L. Buss, University of Florida

Fall armyworm discovery puts all industry on alert

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February 21, 2020

The exotic pest fall armyworm (FAW) Spodoptera frugiperda has been detected for the first time in Australia, in the northern Torres Strait and Northern Queensland.

CRDC and Cotton Australia are calling for people to be aware of what the pest looks like and be alert to its presence.

An Insect ID guide to help distinguish FAW from Northern Australian endemic species is available on the CottonInfo website. The guide was developed by QLD DAF’s Sharna Holman, CottonInfo Biosecurity Technical Lead, with CSIRO Health & Biosecurity, Bayer, NAQS, Plant Health Australia and Northern Territory Department of Primary Industry and Resources. FAW has a strong resemblance to other species in Northern Australia, so careful inspection is required of any suspect specimens.

FAW is a tropical/sub-tropical pest that feeds on around 350 plant species. It prefers warm, moist conditions, and cannot tolerate cool winter temperatures. However, it is a strong flyer and highly mobile, and in North America can expand its range by around 2000 km each year from Florida to Canada, during the warmer months.  

In its native range fall armyworm is often referred to as comprising two subpopulations that look the same and can interbreed, but differ in their distribution, host plant preference and certain physiological features. The sample identified in Australia has been identified as the rice-strain (R strain) which has a host preference for rice, millet, pasture grasses and not the corn-strain (C strain) that feeds on corn, cotton, sorghum.

There are species of Spodoptera already present in Australia which can look similar to fall armyworm. Some are pests, such as lawn armyworm and day-feeding armyworm. Spodoptera litura (cluster caterpillar) is native to Australia and is a minor pest in cotton in Northern Australia.

Climate suitability modelling performed by CSIRO and North-West University has shown that FAW can likely thrive in the northern regions of Australia, with the potential to cause economic impact across North Queensland, Northern Territory, Northern WA, and along northern and eastern regions of Australia where it can persist year-round (red and orange shaded areas). In Queensland and NSW, this includes horticultural and sugar cane producing areas.

“During the warmer months, it is likely to migrate southwards, posing a threat to all of the cropping zones throughout Australia (green shaded areas),” CSIRO’s Wee Tek Tay said.

“The northern cotton region is likely to face year-round pressure from FAW, while the southern cotton producing areas are likely to face FAW as a summer migratory pest, much like green mirids.”

CSIRO has completed considerable work to understand its ecology and how to control it including the presence of resistant genes. Genomic work is also being done on native and invasive FAW populations that are moving throughout the world.

“With the different resistance profiles and host races reported from different populations of FAW in North, Central and South America, understanding the origins of the invasive FAW populations at the global and regional scale will be necessary to help develop management and preparedness strategies for both Australia’s agricultural industries and relevant governmental departments,” Wee Tek said.

“CSIRO in collaboration with partners in China, Europe, Brazil and Africa has been investigating resistance profiles of invasive FAW populations and are planning similar work for the Australian FAW.

“In order to understand whether the invasive FAW is susceptible to Bollgard 3 it will be necessary to understand the origins of the global invasive populations to know whether it carries resistance to Cry2Ab and Vip3A.

“We have also been working with the Department of Agriculture, Water and the Environment and various industries to understand the potential biosecurity threat posed by different pathways of entry.”

To report a sighting call the Exotic Plant Pest Hotline 1800 084 881.