The small brown planthopper (SBPH), Laodelphax striatellus (Fallén) (Hemiptera: Delphacidae), is an important agricultural pest that has caused serious economic losses in the major rice-producing areas of China. To effectively manage this insect pest, we analyzed its genetic variation, genetic structure and population demographic history. We used nine nuclear microsatellite loci to investigate the genetic diversity and population genetic structure of SBPH at 43 sampling sites in China. High levels of genetic diversity and genetic differentiation among most populations were detected. Overall, neighbour-joining dendrograms, STRUCTURE and principal coordinate analysis (PCoA) revealed no genetically distinct groups and exhibited an admixed phylogeographic structure in China. Isolation by distance (IBD) and spatial autocorrelation analyses demonstrated no correlation between genetic distance and geographic distance. On the other hand, bottleneck analysis indicated that SBPH populations had not undergone severe bottleneck effects in these regions. This study provides useful data for resolving the genetic relationships and migration patterns of SBPH and thus contribute to developing effective management strategies for this pest.

Microsatellite amplification and genotyping 

In this study, nine microsatellite loci for SBPH were used. All of these microsatellite loci were explicitly developed for SBPH. Among those, five loci (LS1, LS3, LS6, LS7 and LS8) were chosen from Sun et al. (2012) while other four loci (LS12, LS13, LS15 and LS16) were selected from Sun et al. (2015). These microsatellite loci were assigned unique fluorophores for fluorescent tagging of DNA in a PCR reaction. For these isolated microsatellites, each PCR reaction mixture contained 1.0 units of EasyTaq DNA polymerase, 2.5 mM dNTP mixture, 1×Easy Taq^®buffer (including 2 mM MgCl2; Transgen), 0.5 µl of DNA template, 0.4 µM each of each primer, which was labeled with fluorochromes (HEX or FAM) (10 pM). Conditions for PCR amplification were as follows: 94 °C for 4 min, 30 cycles at 94 °C for 30 s, 58 °C for 30 s, 72 °C for 30 s and a final extension at 72 °C for 5 min. Following amplification, the products were visualized at Sangon Biotech Co., Ltd. (Shanghai, China) using an ABI 3730XL automated sequencer (Applied Biosystems, Foster City, CA, USA). Microsatellite alleles were analyzed using GeneMapper4.0 software (Applied Biosystems).

Laodelphax striatellus microsatellite data

Microsatellite genotype of 43 Laodelphax striatellus populations sampled in China