Regional and seasonal activity predictions for fall armyworm in Australia

James L Maino; Rafael Schouten; Kathy Overton; Roger Day; Sunday Ekesi; Bosibori Bett; Madeleine Barton; Peter C Gregg; Paul A Umina; Olivia L Reynolds

doi:10.1016/j.cris.2021.100010

Regional and seasonal activity predictions for fall armyworm in Australia

Curr Res Insect Sci. 2021 Jan 23:1:100010. doi: 10.1016/j.cris.2021.100010. eCollection 2021.

Authors

James L Maino¹, Rafael Schouten¹, Kathy Overton¹, Roger Day², Sunday Ekesi³, Bosibori Bett⁴, Madeleine Barton¹, Peter C Gregg⁵, Paul A Umina^{1

6}, Olivia L Reynolds^{1

7}

Affiliations

¹ Cesar Australia, 293 Royal Parade, Parkville, Melbourne, Victoria 3052, Australia.
² CABI, Wallingford, UK.
³ International Centre of Insect Physiology and Ecology, Nairobi, Kenya.
⁴ Plant Health Australia, ACT 2600, Australia.
⁵ School of Environmental & Rural Science, University of New England, Armidale NSW 2351, Australia.
⁶ School of BioSciences, The University of Melbourne, Victoria 3010, Australia.
⁷ Graham Centre for Agricultural Innovation, Wagga Wagga NSW 2650, Australia.

Abstract

Since 2016, the fall armyworm (FAW), Spodoptera frugiperda, has undergone a significant range expansion from its native range in the Americas, to continental Africa, Asia, and in February 2020, mainland Australia. The large dispersal potential of FAW adults, wide host range of immature feeding stages, and unique environmental conditions in its invasive range creates large uncertainties in the expected impact on Australian plant production industries. Here, using a spatial model of population growth and spread potential informed by existing biological and climatic data, we simulate seasonal population activity potential of FAW, with a focus on Australia's grain production regions. Our results show that, in Australia, the large spread potential of FAW will allow it to exploit temporarily favourable conditions for population growth across highly variable climatic conditions. It is estimated that FAW populations would be present in a wide range of grain growing regions at certain times of year, but importantly, the expected seasonal activity will vary markedly between regions and years depending on climatic conditions. The window of activity for FAW will be longer for growing regions further north, with some regions possessing conditions conducive to year-round population survival. Seasonal migrations from this permanent range into southern regions, where large areas of annual grain crops are grown annually, are predicted to commence from October, i.e. spring, with populations subsequently building up into summer. The early stage of the FAW incursion into Australia means our predictions of seasonal activity potential will need to be refined as more Australian-specific information is accumulated. This study has contributed to our early understanding of FAW movement and population dynamics in Australia. Importantly, the models established here provide a useful framework that will be available to other countries should FAW invade in the future. To increase the robustness of our model, field sampling to identify conditions under which population growth occurs, and the location of source populations for migration events is required. This will enable accurate forecasting and early warning to farmers, which should improve pest monitoring and control programs of FAW.

Keywords: Agricultural pest; Dispersal; Fall armyworm; Invasive species; Model; Population dynamics.