Fall armyworm research, development and extension for horticulture

Since Fall armyworm (Spodoptera frugiperda, FAW) was first detected in Australia in early 2020, a team of researchers at CSIRO and Macquarie University has been working closely with collaborators to develop biological control agents (BCAs) and management strategies to help mitigate FAW damage on Australian agricultural crops. Here’s an update on their latest research.

Susceptibility of FAW populations to chemical insecticides and Bt

We tested Queensland and Western Australian FAW populations against various classes of chemical insecticides and Bacillus thuringiensis (Bt) toxins and compared their reactions to the endemic pest cotton bollworm (Helicoverpa armigera). We found that FAW are less susceptible to alpha cypermethrin, methomyl, diamide, indoxacarb, chlorantraniliprole, Spinosad, and Cry1AC than the cotton bollworm (ACIAR/GRDC). Furthermore, the level of susceptibility of Queensland and Western Australian FAW populations to those chemicals was different, suggesting that the Queensland and Western Australian populations were genetically diverse (JEE). This supports the idea that global invasive FAW populations have different origins (NCB), and likely involved multiple introduction events into Australia (SR), which will have implications for managing the pest at regional and national scales (ARE).

Biological control agents and endemic natural enemies

To find alternative pest control strategies against FAW, our team have been working on developing BCAs to combat this pest.

At CSIRO, we host many BCA collections including nucleopolyhedrovirus (NPV), Bt, and entomopathogenic fungi (EPF). In the last three years, the team from CSIRO and Macquarie University has tested many of those isolates aiming to find endemic BCAs for FAW. To-date, we have identified two isolates of EPF (BNA) and five isolates of Bt that have shown promising results. Those are now undergoing additional testing, analysis for their mode of action (including via genomics), and verification to ensure safety.

We are also working with the Queensland Department of Agriculture and Fisheries (DAF) in processing infected field samples. This is to detect endemic natural enemies of FAW for the further development of management strategies.

RNA interference gene silencing technology

In addition, we are working with Murdoch University in adopting RNA interference (RNAi) gene silencing technology to help combat FAW. This works by silencing their life-critical genes to weaken the insect and allow other management methods to work against them more efficiently. We have now successfully identified target genes and developed application protocols which have shown significant results working against FAW.

Thanks to: Dr. John Roberts (CSIRO); Dr. Wee Tek Tay (CSIRO, Macquarie University); Dr. Tom Walsh (CSIRO, Macquarie University); Tim Hogarty (CSIRO); Demi Cho (CSIRO); Dr. Rahul Rane (CSIRO, Macquarie University, University of Melbourne); Ray Yang (CSIRO, Murdoch University); Dr. Bishwo Mainali (Macquarie University); Prof. Phil Taylor (Macquarie University); Rajendra Regmi (Macquarie University); Rabia Ali (Macquarie University); Bea Apirajkamol (CSIRO, Macquarie University)

Written by: Bea Apirajkamol (CSIRO, Macquarie University) and Wee Tek Tay (CSIRO)

Figure. CSIRO (Dr Wee Tek Tay and Bea Apirajkamol), ASQ (Dr Heidi Parkes and Vasanthaverni Subramaniam) and VegNET Regional Development Officer (David Shorten) inspecting fall armyworm in a sweet corn trial at DAF, Bowen Queensland.