Genetic structure and insecticide resistance characteristics of fall armyworm populations invading China.

Lei Zhang ,Bei Liu ,Christopher M Jones ,Shengyuan Zhao ,Emmanuelle D’alençon ,Kongming Wu ,Bo Liu ,Kenneth Wilson ,Xinming Yang ,Dandan Zhang ,Wei Fan ,Guirong Wang ,Wengang Zheng ,Jie Liu ,Weipeng Quan ,Xinyue Liang ,Conghui Liu ,Pengjun Xu ,Swapan Chakrabarty ,Donald L Kachigamba ,Kiwoong Nam ,Amy J Withers ,Chao Wu ,Judith A Smith ,Minghui Jin ,Xiaolin Liu ,Yuying Jiang ,Zaiyuan Li ,Wanqiang Qian ,Gilson Chipabika ,Yutao Xiao

doi:10.1111/1755-0998.13219

Abstract

The rapid wide‐scale spread of fall armyworm (Spodoptera frugiperda) has caused serious crop losses globally. However, differences in the genetic background of subpopulations and the mechanisms of rapid adaptation behind the invasion are still not well understood. Here we report the assembly of a 390.38‐Mb chromosome‐level genome of fall armyworm derived from south‐central Africa using Pacific Bioscience (PacBio) and Hi‐C sequencing technologies, with scaffold N50 of 12.9 Mb and containing 22,260 annotated protein‐coding genes. Genome‐wide resequencing of 103 samples and strain identification were conducted to reveal the genetic background of fall armyworm populations in China. Analysis of genes related to pesticide‐ and Bacillus thuringiensis (Bt) resistance showed that the risk of fall armyworm developing resistance to conventional pesticides is very high. Laboratory bioassay results showed that insects invading China carry resistance to organophosphate and pyrethroid pesticides, but are sensitive to genetically modified maize expressing the Bt toxin Cry1Ab in field experiments. Additionally, two mitochondrial fragments were found to be inserted into the nuclear genome, with the insertion event occurring after the differentiation of the two strains. This study represents a valuable advance toward improving management strategies for fall armyworm.

Highlights

IntroductionThe pest was first detected in Africa in 2016 (Goergen et al, 2016) and spread to 44 African countries within two years
After interaction analysis based on a total of 78 Gb data obtained through Hi-C sequencing, 143 contigs were concatenated to 31 linkage groups with a scaffold N50 of 12.9 Mb, accounting for 96.3% of total genome length (Fig. 1)
The results showed that all the samples, including the four from Africa, had more than 70% of the genetic background of the American C-strain (ASW) genotype

Summary

Introduction

The pest was first detected in Africa in 2016 (Goergen et al, 2016) and spread to 44 African countries within two years. It was detected in India in 2018, and it has spread to several southeastern Asian countries (Nagoshi et al, 2020). Such rapid spread poses a global threat to food production. There is no absolute mating barrier between the two strains and productive hybridization has been confirmed in both laboratory and field studies (Dumas et al, 2015; Nagoshi, Meagher, Nuessly, & Hall, 2006)

Methods

Results

Conclusion