Abstract: 【Aim】 The oriental fruit moth, Grapholitha molesta is an important worldwide fruit pest. The midgut of insects plays an important role in digestion, immune response, growth and development. The aim of this study is to establish the larval midgut transpcriptome database of G. molesta, and to tap its genetic information. 【Methods】 The larval midgut transcriptome of G. molesta was sequenced, assembled and subjected to bioinformatics analysis by using a high throughput sequencing platform (Illumina HiSeq X Ten), and then the SSR molecular markers from the larval midgut were identified by using the transcriptome data. 【Results】 A total of 96 419 unigenes in the larval midgut transcriptome of G. molesta were obtained, and 57 300 unigenes were annotated in the public databases. All unigenes were assigned to 55 functional sub-categories of three categories (biological processes, cellular components and molecular function) using Gene Ontology, and a lot of unigenes were annotated to be related to cellular process, cell and cell part, and binding. The results of KOG showed that 10 090 sequences were classified into 25 gene families, with the most annotated to the general function. In the KEGG database, 10 250 unigenes were annotated to 232 metabolic pathways, and the number of genes annotated to ribosomes was the most. In addition, using MISH software, 12 690 SSR loci were searched in 10 600 unigenes, and six SSR loci were developed by PCR. 【Conclusion】 In this study we successfully assembled the larval midgut reference transcriptome of G. molesta, which provides a theoretical basis for pest control targeting the midgut.

Key words: Grapholitha molesta, midgut, transpcriptome, SSR, molecular marker, Illumina HiSeq