Comparative transcriptome analysis of Tamarixia radiata (Hymenoptera: Eulophidae) reveals differentially expressed genes upon heat shock.

Temperature is a key parameter that affects insect population, abundance, and distribution in tropical and subtropical regions. Tamarixia radiata Waterson (Hymenoptera: Eulophidae) is a species-specific ectoparasitoid widely used as a biological control agent for the major citrus pest Diphornia citri Kuwayama (Hemiptera: Liviidea). To date, T. radiata response to high temperature at the molecular level still is unclear. In this study, we conducted a comparative analysis of the transcriptomes of T. radiata exposed at 25 °C and 38 °C for 15 min. A total of 51,072 unigenes were obtained, 22,413 annotated with a mean length of 1054 bp. Differential expression analysis showed that 502 genes were identified, including 476 genes significantly up-regulated and 26 genes down-regulated after heat stress exposure. The Gene Ontology analysis showed that most enriched DEGs are categorized into "cellular process", "metabolic process" and "DNA binding." In addition, "Lysosome," "Longevity regulating pathway-multiple species," and "starch and sucrose metabolism" were highly enriched in Kyoto Encyclopedia of Genes and Genomes pathways. Transcriptome analyses showed that heat stress significantly induced the transcription of the molecular chaperone, immune response, stress signaling transduction, and oxidation resistance, including highly expressed heat shock proteins, ATPases, and detoxifying enzymes. Furthermore, the expression patterns of thirteen genes including heat shock proteins (HSP), glutathione S-transferase (GST) and cytochrome P450 were consistent with the transcriptome results obtained through qRT-PCR. Together, our results provided a comprehensive study of the molecular response of T. radiata to heat stress and provides new insight for the future functional validation of heat resistance-related genes.