Comparative analysis of fecundity related traits and transcriptome in two isofemale lines of the egg parasitoid, Trichogramma dendrolimi (Matsumura)

Abstract

The egg parasitoid, Trichogramma dendrolimi, plays an important role as a biological control agent for the control of various lepidopteran pests. The reproductive capacity of T. dendrolimi is essential for both mass-rearing and effective pest control. In this study, a T. dendrolimi line with a high fecundity trait (Td-H) and another with a low fecundity trait (Td-L) were selected from 13 isofemale lines collected across different regions of China. The fecundity trait of Td-H and Td-L females was validated through assessments of oocyte number in the ovary, fecundity, body size, and adult longevity. To investigate the expression patterns of fecundity-related genes in T. dendrolimi, transcriptomes of Td-H and Td-L females were sequenced and compared. A total of 441 differentially expressed genes (DEGs), including 181 up-regulated genes and 260 down-regulated genes, were identified. Moreover, 11 genes were specifically expressed in Td-H females, while 16 genes were exclusive to Td-L females. These DEGs were mainly enriched in categories such as “metabolic process” (102 DEGs), “organelle”(53 DEGs), “catalytic activity” (90 DEGs), and “binding” (174 DEGs) in GO analysis, as well as various metabolic pathways (58 DEGs) and the “Neuroactive ligand-receptor interaction” pathway (22 DEGs) in KEGG analysis. The accuracy of seven up-regulated DEGs and seven down-regulated DEGs in the transcriptome was confirmed using RT-qPCR. These findings will be helpful for investigating the regulatory mechanisms associated with the fecundity traits of T. dendrolimi and provide a reference for improving biological control agents against pests.