Fall armyworm: what threat does it pose, and what tools do we have to manage it?

Take home message

Since its arrival in Australia, Fall armyworm (FAW) has been active in the tropics, impacting maize and sweetcorn crops. FAW infestation of maize in North Qld (Burdekin, Bowen regions) has been continuous, from emergence to maturity. Consequently, crop growth rates and yield potential are significantly impacted. Infestations during cob-fill result in significant reductions in yield and grain quality, as a result of secondary infections entering the cobs.

FAW larvae have proved extremely difficult to control with insecticides. The frequency of egg lays, and the hidden feeding sites of larvae (in the whorl, under wrapper leaves, in leaf axils, in silks and cobs) makes chemical control only partially effective.

FAW has been observed feeding in other crops (sorghum, millet, summer pulses), but to date these crops have experienced only minor feeding damage.

It is very clear that affected industries cannot rely on insecticides alone to manage FAW. To date, little effective natural enemy activity has been observed. Whilst selective insecticides have been used preferentially, in maize these are limited to 2 applications per crop, and the broad-spectrum options are highly disruptive to natural enemies.

In maize, FAW has been managed effectively in other countries for many years with transgenic Bt crops a primary means of controlling FAW. Bt provides continuous control of larvae through the vegetative stages (in particular), and in feeding in sites where they cannot be easily contacted with conventional insecticides.

Managing FAW without transgenic crops will be a major challenge for Australian growers, particularly in tropical regions where FAW are attacking crops from emergence to maturity.

In regions where crops are infested by FAW for only part of the growing season, or sporadically in outbreak years, the challenges are less, but not insignificant.

The effective management of FAW will rely on a combination of timely detection (regional trapping information and crop scouting), suppression of populations by natural enemies and deployment of insecticides and other options to control larvae in the crop.

Useful resources

The Beatsheet Blog

Find information on FAW in the “Key Pests and Management” page. Includes information on identification, webinars, pheromone trap network data.

From the “Resources” page, you can access the DARABUG2 development model. This tool provides predicted development rates of FAW (and other species). Useful for calibrating yourself in terms of the rate of development of eggs, larvae and pupae.

The GRDC Fall Armyworm portal provides access to a range of important information for Australian grain growers.

A list of current permits for FAW insecticide options is searchable at the APVMA  PUBCRIS portal.

Follow @bwilson_71 (Twitter) for insights into an agronomist’s first-hand experience with FAW in north Qld.

Contact details

Melina Miles
Queensland Department of Agriculture and Fisheries
Mb: 0407 113 306
Email: Melina.Miles@daf.qld.gov.au