The common cutworm, Spodoptera litura (Lepidoptera: Noctuidae), is a voracious agricultural pest.  To increase understanding of the migration patterns and genetic diversity of different geographic populations of this species, we analyzed genetic variation in nine microsatellite loci among 576 individuals collected from 17 locations in China and one in Myanmar during 2011–2012.  We successfully identified 162 alleles, with an average of 18 alleles per locus and a range of 5 to 34.  The mean observed heterozygosity of the 18 populations ranged from 0.18 to 0.98, and the expected heterozygosity ranged from 0.19 to 0.89.  For the nine microsatellite markers studied, polymorphism information content ranged from 0.18 to 0.88 (mean=0.64).  We found low genetic differentiation among the 18 populations (mean F-statistics (F_ST)=0.05) and high genetic diversity among individuals.  Principle coordinates analysis indicated no significant correlation between geographic and genetic distance (r=0.04).  The value of  N_m (N_m>4)  estimated using coalescent-based methods suggests strong gene flow with migration.  The nine microsatellite markers identified in this study will be beneficial for further investigation of migration patterns and genetic diversity in S. litura.

 

Quantitative reverse transcription polymerase chain reaction (qRT-PCR) is the most commonly-used tool for measurement of gene expression, but its accuracy and reliability depend on appropriate data normalization with the use of one or more stable reference genes.  Adelphocoris suturalis is one of the most destructive pests of cotton, but until recently knowledge of its underlying molecular physiology had been hindered by a lack of molecular resources.  To facilitate research on this pest, we evaluated 12 common housekeeping genes studied in insects (GAPDH, ACT, βACT, TBP, SDH, βTUB, EF1γ, EF1α, EF1δ, RPL32, RPS15, and RPL27) for their expression stability in A. suturalis when subjected to various experimental treatments, including three biotic (developmental stage and sex, tissue type, and metathoracic scent gland for varying developmental stages and sexes) and one abiotic (RNA interference injection) conditions.  Four dedicated algorithms (ΔCt method, geNorm, BestKeeper and NormFinder) were used to analyze gene expression stability.  In addition, RefFinder provided an overall ranking of the stability/suitability of these candidates.  This study is the first to provide a comprehensive list of suitable reference genes for gene expression analyses in A. suturalis, which can serve to facilitate transcript expression study of related biological processes in this and related species.