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A diagnostic LAMP assay for rapid identification of an invasive plant pest, fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae)

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posted on 2022-07-29, 05:38 authored by A Agarwal, L Rako, MK Schutze, ML Starkie, WT Tay, Brendan RodoniBrendan Rodoni, MJ Blacket
Fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae), is a highly polyphagous invasive plant pest that has expanded its global geographic distribution, including recently into much of Australia. Rapid diagnostic tests are required for identification of FAW to assist subsequent management and control. We developed a new loop-mediated isothermal amplification (LAMP) assay based on the mitochondrial cytochrome c oxidase subunit I (COI) gene for accurate and timely diagnosis of FAW in the field. The specificity of the new assay was tested against a broad panel of twenty non-target noctuids, including eight other Spodoptera species. Only S. frugiperda samples produced amplification within 20 min, with an anneal derivative temperature of 78.3 ± 0.3 °C. A gBlock dsDNA fragment was developed and trialled as a synthetic positive control, with a different anneal derivative of 81 °C. The new FAW LAMP assay was able to detect FAW DNA down to 2.4 pg, similar to an existing laboratory-based real-time PCR assay. We also trialled the new FAW assay with a colorimetric master mix and found it could successfully amplify positive FAW samples in half the time compared to an existing FAW colorimetric LAMP assay. Given the high sensitivity and rapid amplification time, we recommend the use of this newly developed FAW LAMP assay in a portable real-time fluorometer for in-field diagnosis of FAW.

Funding

We thank the Australian Department of Agriculture, Water and Environment (DAWE) for funding this research (Project Identification Number 188450, completed May 2021). Elizabeth McCrudden (DAWE) and Martin Bluml (AgVic) assisted with project management. Linda Semeraro (AgVic), Lixin Eow (AgVic) and Isabel Valenzuela (AgVic) provided the Victorian CHS surveillance FAW and related species samples for this project. We thank Subramaniam Siva (QDAF) for providing the FAW specimens and other related species collected from FAW pheromone traps in Queensland. CSIRO specimens of Spodoptera exigua, S. orchrea, S. ornithogalli, S. litura and S. littoralis were provided by DAWE, while S. cosmoides and S. eridania were provided by Prof. Cecilia Czepak (Federal University of Goias, Brazil; IBAMA Permit Number: 18BR028445/DF). We thank David Britton and Todd Greenwood (DAWE) for providing specimens of S litura from Papua New Guinea for LAMP testing; and Elizabeth McCrudden (DAWE) and Bobbie Hitchcock (DAWE) for reviewing the project report and providing helpful suggestions for this study. We also thank Dr Andreas Zwick (CSIRO) for discussion on the taxonomic status of Leucania loreyi.

History

Publication Date

2022-12-01

Journal

Scientific Reports

Volume

12

Issue

1

Article Number

ARTN 1116

Pagination

15p.

Publisher

Springer Nature

ISSN

2045-2322

Rights Statement

© The Author(s) 2022. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.