Phaedrotoma sp.2 Parasitism on Host Liriomyza trifolii Metabolic and Immune Regulations by Transcriptome Analysis

Parasitoids are crucial natural enemies of Liriomyza trifolii, a globally notorious pest. Upon parasitization, host metabolism and immune responses were profoundly disrupted, thereby favoring the development of wasps offsprings. However, the underlying regulatory mechanisms remain elusive. In this study, transcriptome sequencing was utilized to investigate the host metabolic and immune response changes at 4 h, 12 h, and 24 h postparasitization by Phaedrotoma sp.2. We identified 4070 differentially expressed genes, enriched in metabolic (e.g., tricarboxylic acid cycle, insulin synthesis) and immune (e.g., Toll/Imd pathways) pathways, and RT-qPCR further validated core gene expressions involved in these pathways. Physiological analyses revealed that Phaedrotoma sp.2 parasitism altered the host larvae's protein, lipid, and sugar content, inhibited hemocyte spreading, increased hemocyte mortality, and suppressed hemolymph melanization. Collectively, this study sheds light on the host metabolic and immune modulation by Phaedrotoma sp.2 parasitism and provides a novel insight into the mechanisms underpinning their interactions. This discovery lays a solid foundation for the practical application of parasitoids in biological control programs.