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Fall armyworm steps and lessons

Fall armyworm.
Photo: John C. French Sr,

The arrival of fall armyworm (FAW) in 2020 is a timely illustration of the importance of being forewarned and forearmed.

Australia’s biosecurity system at the Commonwealth, state and territory levels was prepared for the arrival of FAW and this allowed immediate actions to be taken, including;

  • issuing of emergency permits for FAW control options;
  • making available FAW identification guides;
  • hosting webinars and training events to update industry;
  • rapidly putting into place networks of pheromone traps for early detection of the FAW moth in new regions to share information; and
  • making diagnostic services available to confirm moth and larvae identifications.

An important step taken by GRDC was to invest in the development of a ‘continuity plan’ for FAW. This plan collated information about the pest’s biology, behaviour and management in similar crops and environments overseas. This information guided actions until further local research could be completed.

Since FAW arrived in Australia, the northern tropics have experienced continuous infestations of maize crops. Crop growth rates and yield are affected, as well as grain quality due to secondary infections entering the cobs.

Seasonal migrations are likely to result in annual southerly distribution of FAW into areas of grain production in southern Queensland, southern Western Australia, New South Wales, Victoria and, in some years, South Australia and Tasmania.

FAW is an extremely challenging pest to manage with insecticides. This is due to the frequency of egg lays and concealed feeding sites of larvae (in the whorl, silks and cobs). This renders chemical control only partially effective. To optimise the cost of insecticide applications, surveillance using moth traps and in-field monitoring for larvae and crop damage is critical as it allows targeting of the most vulnerable life stages.

Another challenging aspect is FAW’s strong track record of developing insecticide resistance. Global reliance on chemical control resulted in resistance to at least 29 insecticide active ingredients in six mode-of-action groups.

In Australia, toxicity profiles of insecticide groups that are available for FAW control have been generated to help develop sustainable management strategies. This work was undertaken by the NSW Department of Primary Industries (DPI) in partnership with the Queensland Department of Agriculture and Fisheries (DAF) and the Western Australian Department of Primary Industries and Regional Development (DPIRD), with support from the Cotton Research and Development Corporation (CRDC).

Over the past two seasons, this information assisted decision-making by growers managing outbreaks and has promoted the recommended thresholds and integrated pest management (IPM) practices outlined in the Fall Armyworm Continuity Plan (link below).

This research also resulted in the development of diagnostic tests for detection of resistance in FAW to IPM-compatible insecticides. Ongoing resistance surveillance will be important to preserve the activity of selective insecticides (with low non-target impacts) and enhance IPM in grains.

These testing procedures will be implemented in a new collaboration between DAF and DPI to deliver resistance surveillance in key crop production regions of Queensland. The results from the project will help to guide further research by public and private agencies to develop and improve FAW management strategies.

Pheromone and lures

A collaborative project led by Macquarie University, with investment from Hort Innovation Australia and GRDC, aims to optimise pheromone blends and reduce by-catch in the lures used in moth surveillance.

Increased lure specificity will reduce the requirement for diagnostic services and could provide a pathway to fully transition surveillance to industry in the longer term. This project has a national focus and involves collaborators at New South Wales Department of Primary Industries, Queensland Department of Agriculture and Fisheries, Western Australian Department of Primary Industries and Regional Development, the Northern Territory Department of Agriculture and Fisheries and CSIRO.

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