Whole genome resequencing of pink stem borer (Part 1/4)

Understanding the genetic basis of adaptive evolution following habitat
expansion can have important implications for pest
management. The pink stem borer (PSB), Sesamia inferens
(Walker), is a destructive pest of rice that was historically restricted
to regions south of N34° latitude in China. However, with changes in
global climate and farming practices, the distribution of this moth has
progressively exceeded its traditional limit of 34° N and encompassed most
regions in North China. However, the evolutionary processes and local
adaptative changes of this species, are not yet fully
understood. Here, we employed genome resequencing to genotype
over 1 million of high‐quality SNPs and 20,000 SVs from 14 geographical
populations across China. Three highly differentiated genetic groups were
formed, corresponding to Northern and Southern China regions and the
Yunnan-Guizhou Plateau. The pairwise genetic distance between locations
was highly correlated with geographic and environmental distance. Our
estimates of evolutionary history indicate asymmetric migration with
varying population sizes across three genetic groups. Selective sweep
analyses highlight the strongly selected insect cuticle GRP genes enhanced
desiccation adaptability of the northern group and SETMAR gene associated
with range expansion and local adaptation in the Shandong population.
Based on an integrated analysis of transcriptome and enGWAS, we also
identified the CYP321A7 gene as being involved in the PSB
adaption to desiccation climates. Our findings revealed the
phylogeography, demographic dynamics and evolutionary forces of PSB and
identified potential candidate genes to explore the genetic adaptation to
novel environments, which have significant implications for the
development of effective strategies to control this pest.