Patterns of genetic variation among geographic and host-plant associated populations of the peach fruit moth Carposina sasakii (Lepidoptera: Carposinidae).

BACKGROUND: Populations of herbivorous insects may become genetically differentiated because of local adaptation to different hosts and climates as well as historical processes, and further genetic divergence may occur following the development of reproductive isolation among populations. Here we investigate the population genetic structure of the orchard pest peach fruit moth (PFM) Carposina sasakii (Lepidoptera: Carposinidae) in China, which shows distinct biological differences when characterized from different host plants. Genetic diversity and genetic structure were assessed among populations from seven plant hosts and nine regions using 19 microsatellite loci and a mitochondrial sequence. RESULTS: Strong genetic differentiation was found among geographical populations representing distinct geographical regions, but not in host-associated populations collected from the same area. Mantel tests based on microsatellite loci indicated an association between genetic differentiation and geographical distance, and to a lesser extent environmental differentiation. Approximate Bayesian Computation analyses supported the scenario that PFM likely originated from a southern area and dispersed northwards before the last glacial maximum during the Quaternary. CONCLUSIONS: Our analyses suggested a strong impact of geographical barriers and historical events rather than host plants on the genetic structure of the PFM; however, uncharacterized environmental factors and host plants may also play a role. Studies on adaptive shifts in this moth should take into account geographical and historical factors.

Development and Characterization of Novel Microsatellite Markers for the Peach Fruit Moth Carposina sasakii (Lepidoptera: Carposinidae) Using Next-Generation Sequencing.

The peach fruit moth Carposina sasakii is an economically important pest on dozens of fruits from Rosaceae and Rhamnaceae in Northeast Asia. We developed novel microsatellite markers for C. sasakii from randomly sequenced regions of the genome using next-generation sequencing. In total, 95,153 microsatellite markers were isolated from 4.70 GB genomic sequences. Thirty-five polymorphic markers were developed by assessing in 63 individuals from two geographical populations. The allele numbers ranged from 2 to 9 with an average value of 4.60 per locus, while the polymorphism information content ranged from 0.075 to 0.696 with an average value of 0.407. Furthermore, the observed and expected heterozygosity varied from 0.000 to 0.677 and 0.062 to 0.771, respectively. The microsatellites developed provide abundant molecular markers for investigating genetic structure, genetic diversity, and existence of host-plant associated biotypes of C. sasakii.

The mitochondrial genome of the garden pea leafminer Chromatomyia horticola (Goureau, 1851) (Diptera: Agromyzidae).

Here we report the mitochondrial genome sequence of the garden pea leafminer Chromatomyia horticola (Goureau, 1851) (Diptera: Agromyzidae) (GenBank accession no. KR047789). This is the first species with sequenced mitochondrial genome from the genus Chromatomyia. The current length with partial A + T-rich region of this mitochondrial genome is 15,320 bp with an A + T content of 77.54%. All the 13 protein-coding, two rRNA, and 22 tRNA genes were sequenced, except for the A + T-rich region. As in most other sequenced mitochondrial genomes of Diptera, there is no rearrangement compared with the pupative ancestral arrangement of insects. All protein-coding genes start with the ATN start codon except for the gene cox1, which uses abnormal TTG. The A + T-rich region is located between rrnS and trnI with a sequenced length of 503 bp. Phylogenetic analysis using the Bayesian method based on the first and second codon positions of the 13 protein-coding genes recovered the monophyly of Agromyzidae with one species of Chromatomyia and four species of Liriomyza in our study. The superfamily Oestroidea (with Agromyzidae in analysis) is sister to the Opomyzoidea.