Effects of Antheraea pernyi (Lepidoptera: Saturniidae) eggs infected by Serratia marcescens (Enterobacterales: Yersiniaceae) on the fitness and transcriptome of Trichogramma chilonis (Hymenoptera: Trichogrammatidae).

Abstract

To clarify the molecular responses of Trichogramma chilonis (Hymenoptera: Trichogrammatidae) to the diseased gray eggs of Antheraea pernyi (Lepidoptera: Saturniidae), transcriptome sequencing analysis of Trichogramma adults reared on gray eggs and healthy eggs was carried out using high-throughput sequencing on the Illumina HiSeq 2000 platform. Subsequent to RNA-seq, 34,404 assembled unigenes were identified, and 15,405 of these were annotated in the transcriptome libraries of T. chilonis. In addition, 101 differentially expressed genes (DEGs) were detected, including 8 significantly upregulated and 93 significantly downregulated genes. Functional classification revealed that biological process, cellular component, and molecular function categories were significantly enriched. According to the Clusters of Orthologous Groups classification, the DEGs were mainly enriched in "posttranslational modification, protein turnover, chaperone" and "carbohydrate transport and metabolism." Moreover, tryptophan metabolism, arginine and proline metabolism, and nitrogen metabolism were significantly enriched among the metabolic and signaling pathways. Fourteen downregulated genes related to insect growth, development, and immune mechanisms were identified from the annotation results. Under paired-choice conditions, T. chilonis showed a significant preference for healthy A. pernyi eggs over gray ones in terms of parasitism rate. However, no significant differences were observed in offspring emergence rate between the 2 host types. Finally, 8 DEGs were chosen for validation via real-time quantitative polymerase chain reaction, exhibiting expression trends consistent with the RNA-seq data. Taken together, these findings provide a molecular biological basis for understanding the effects of A. pernyi gray eggs on T. chilonis.