Immigration of Sogatella furcifera from the Greater Mekong Subregion into northern China revealed by 2b-RAD sequencing

Background The white-backed planthopper (WBPH), Sogatella furcifera
(Horváth) (Hemiptera, Delphacidae), is a migratory pest of rice in Asia.
Shandong Province, in northern China, is located on the migration pathway
of WBPH between southern and northeast China. The potential sources of
WBPH in northern China are poorly understood. We studied the sources of
WBPH in Shandong Province by determining the population genetic structure
of WBPH in 18 sites distributed in Shandong and in six regions of the
Greater Mekong Subregion (GMS). We used mitochondrial gene and
single-nucleotide polymorphism (SNP) markers (2b-RAD sequencing) for
analysis. Results All of the WBPH populations studied in the seven regions
had low genetic diversity. Pairwise F ST values ranged from -0.061 to
0.285, while F ST based on SNP data ranged from -0.007 to 0.009. These two
molecular markers revealed that 4.40% (mtDNA) and 0.19% (SNP) genetic
variation could be explained by the interpopulation variation, while the
rest came from intrapopulation variation. The populations in the seven
geographic regions comprised four hypothetical genetic clusters (K = 4)
not associated with geographic location. Eighty-four of 129 individuals
distributed across the given area were designated as recent migrants or of
admixed ancestry. Although the substantial migration presented, a weak but
significant correlation between genetic and geographic distances was found
(r = 0.083, P = 0.004). Conclusion GMS was the main source of WBPH in
Shandong, while other source populations may also exist. The genetic
structure of WBPH is shaped by both migration and geographic barriers.
These results help clarify the migration route and the source of WBPH in
northern China.