Abstract
AbstractThe fall armyworm (FAW)Spodoptera frugiperdais present in over 70 countries in Africa, Asia, and Oceania. Its rapid dispersal since 2016 when it was first reported in western Africa, and associated devastation to agricultural productivity, highlight the challenges posed by this pest. Currently, its management largely relies on insecticide sprays and transgenicBacillus thuringiensistoxins, therefore understanding their responses to these agents and characteristics of any resistance genes enables adaptive strategies. In Australia,S. frugiperdawas reported at the end of January 2020 in northern Queensland and by March 2020, also in northern Western Australia. As an urgent first response we undertook bioassays on two Australian populations, one each from these initial points of establishment. To assist with preliminary sensitivity assessment, two endemic noctuid pest species,Helicoverpa armigeraandSpodoptera litura, were concurrently screened to obtain larval LC50 estimates against various insecticides. We characterised known resistance alleles from the VGSC, ACE-1, RyR, and ABCC2 genes to compare with published allele frequencies and bioassay responses from native and invasiveS. frugiperdapopulations. An approximately 10x LC50 difference for indoxacarb was detected between Australian populations, which was approximately 28x higher than that reported from an Indian population. Characterisation of ACE-1 and VGSC alleles provided further evidence of multiple introductions in Asia, and multiple pathways involving genetically distinct individuals into Australia. The preliminary bioassay results and resistance allele patterns from invasiveS. frugiperdapopulations suggest multiple introductions have contributed to the pest’s spread and challenge the axiom of its rapid ‘west-to-east’ spread.
Publisher
Cold Spring Harbor Laboratory
Cited by
2 articles.
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