Preliminary characterisation of known pesticide resistance alleles in Spodoptera frugiperda (Lepidoptera: Noctuidae) in its invasive Australian range

Abstract

Fall armyworm (Spodoptera frugiperda) has recently been detected in Australia. Globally, S. frugiperda is reported to be resistant to insecticides, including those permitted for its control by the Australian Pesticides and Veterinary Medicines Authority. Consequently, an understanding of the insecticide resistance status of newly migrated S. frugiperda into Australia, as well as an ability to accurately identify newly hatched larvae, would facilitate sustainable management. To aid identification, we developed a real‐time polymerase chain reaction diagnostic assay that can identify S. frugiperda species, irrespective of life stage, and distinguish between the rice and corn strains. We then screened S. frugiperda individuals from Queensland, Western Australia, the Northern Territory and New South Wales for mutations causing target site insensitivity in the acetylcholinesterase (AChE) gene, the voltage‐gated sodium channel gene and the ryanodine receptor gene. In the populations tested, we found that mutation at positions A210S and F290V in AChE were common. These mutations are known to be associated with carbamate and organophosphate resistance in S. frugiperda outside Australia. In contrast, no mutation was found in gene voltage‐gated sodium channel causing pyrethroid resistance or the ryanodine receptor gene associated with diamide resistance. As S. frugiperda is new to Australia, the wide distribution of mutations in the AChE gene associated with organophosphate/carbamate resistance suggests that the original migrated S. frugiperda moths may have carried the mutations from outside Australia. As resistance genes have been detected, it is important to continue to monitor the resistance status of Australian S. frugiperda and further integrate complementary bioassay when available. Finally, as pesticide resistance is possible, it should be additionally considered when making pest management decisions and any spray failure should be followed by a pesticide from a different chemical group.

Invasiveness, biology, ecology, and management of the fall armyworm, Spodoptera frugiperda

“…Local selection caused by intensive insecticide use is the primary driver of evolution of insecticide resistance. However, FAW is a migratory species in which resistance alleles can spread when new areas are invaded (Arias et al 2019;Yainna et al 2021;Nguyen et al 2021).…”

“…A combination of ecological and operational factors makes a perfect storm for FAW resistance evolution in Puerto Rico, including high infestation, more than 10 armyworm generations per year, relative isolation, temperatures favorable for rapid insect development, and up to 29 sprays per season (Storer et al 2012;Gutierrez-Moreno et al 2019) The potential for FAW movement to spread alleles conferring resistance to Bt toxins and other insecticides is a concern, especially as FAW in Africa and Asia share a common origin from the Eastern Hemisphere (Nagoshi et al 2020b). Although some mutations conferring resistance to organophosphates and pyrethroids apparently spread from the Eastern Hemisphere to Australia (Nguyen et al 2021), mutations conferring resistance to Bt toxins in Puerto Rico and Brazil were not detected in Africa ( Van den Berg et al 2021b).…”

Resistance Bioassays and Allele Characterization Inform Analysis of Spodoptera frugiperda (Lepidoptera: Noctuidae) Introduction Pathways in Asia and Australia

“…A total of 1,177 individuals representing 75 populations in Supp Table 2 (online only ) were used to compile the data below. Population identity is as provided in Supp Table 2 (online only ) that combined data from this study (Australia SF20-1 and SF20-4 (generation 0 representing field-collected individuals), PNG, South Korea) and from published studies ( Boaventura et al 2020a , Zhang et al 2020 , Zhao et al 2020 , Guan et al 2021 , Nguyen et al 2021 , Tay et al 2021 , Yainna et al 2021 , Rane et al 2022 ). Susceptible and resistant alleles from the three previously reported loci (i.e., F290V, G227A, A201S) from the ACE-1 gene provided evidence to support multiple independent introductions across the invasive S. frugiperda populations, such as in (b) Indonesia (#2; G227A) and South Korea (#4; F290V), and in (c) China (Hubei province (#10-13); G227A) as indicated by the arrows.…”

Resistance bioassays and allele characterisation inform analysis ofSpodoptera frugiperda(Lepidoptera: Noctuidae) introduction pathways in Asia and Australia

“…A total of 1,177 individuals representing 75 populations in Table S2 were used to compile the data below. Population identity is as provided in Table S2 that combined data from this study (Australia SF20-1 and SF20-4 (generation 0 representing field-collected individuals), PNG, South Korea) and from published studies (Boaventura et al 2020a, Guan et al 2020, Zhang et al 2020, Zhao et al 2020, Nguyen et al 2021, Tay et al 2021, Yainna et al 2021, Rane et al 2022). Susceptible and resistant alleles from the three previously reported loci (i.e., F290V, G227A, A201S) from the ACE-1 gene provided evidence to support multiple independent introductions across the invasive S. frugiperda populations, such as in (b) Indonesia (#2; G227A) and South Korea (#4; F290V), and in (c) China (Hubei province (#10-13); G227A) as indicated by the red arrows.…”