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.

Sogatella furcifera individuals were sampled in various geographic regions (China and Southeast Asia). These comprised six sites in Yunnan Province; four sites in Shandong Province; two sites in Laos, Cambodia, and Vietnam, respectively; and one site in Myanmar and Thailand, respectively. Samples were put in 95% ethanol and stored at -20°C until DNA extraction. Insect DNA was extracted using the TIAMamp Micro DNA Kit (Tiangen, Beijing, China) according to the manufacturer protocol. The 2b-RAD sequencing and genotyping were outsourced to Shanghai OE Biotech Ltd. (Shanghai, China). The genotype data contained information for each locus and each individual were obtained as vcf file.