The citrus red mite, Panonychus citri, is known for its ability rapidly to evolve resistance to insecticides/acaricides and to adapt to hosts that produce toxins. In this study, we constructed an unprecedented four gigabase pair transcriptome of P. citri, which was assembled into 64 149 unique transcripts, the functions of which were annotated by five public databases. A total of 116 unique transcripts were identified as representatives of potential involvement in the detoxification of xenobiotics. Genes recorded to encoding insecticide/acaricide target proteins were also obtained from the P. citri transcriptome. In order to explore novel candidate genes potentially involved in the pesticide detoxification of P. citri, we also constructed digital gene expression libraries of short-term transcriptome responses of P. citri to pesticides, which resulted in the identification of 120 unique transcripts potentially associated with insecticide/acaricide detoxification. Our study will facilitate molecular research on pesticide resistance in citrus red mites, as well as in other phytophagous mites.

The citrus whitefly, Dialeurodes citri (Ashmead), is one of the three economically important whitefly species that infest citrus plants around the world; however, limited genetic research has been focused on D. citri, partly because of lack of genomic resources. In this study, we performed de novo assembly of a transcriptome using Illumina paired-end sequencing technology (Illumina Inc., San Diego, CA, USA). In total, 36,766 unigenes with a mean length of 497 bp were identified. Of these unigenes, we identified 17,788 matched known proteins in the National Center for Biotechnology Information database, as determined by Blast search, with 5731, 4850 and 14,441 unigenes assigned to clusters of orthologous groups (COG), gene ontology (GO), and SwissProt, respectively. In total, 7507 unigenes were assigned to 308 known pathways. In-depth analysis of the data showed that 117 unigenes were identified as potentially involved in the detoxification of xenobiotics and 67 heat shock protein (Hsp) genes were associated with environmental stress. In addition, these enzymes were searched against the GO and COG database, and the results showed that the three major detoxification enzymes and Hsps were classified into 18 and 3, 6, and 8 annotations, respectively. In addition, 149 simple sequence repeats were detected. The results facilitate the investigation of molecular resistance mechanisms to insecticides and environmental stress, and contribute to molecular marker development. The findings greatly improve our genetic understanding of D. citri, and lay the foundation for future functional genomics studies on this species.