Genome assembly of the ectoparasitoid wasp Theocolax elegans

The ectoparasitoid wasp Theocolax elegans is a cosmopolitan and generalist pteromalid parasitoid of several major storage insect pests, and can effectively suppress a host population in warehouses. However, little molecular information about this wasp is currently available. In this study, we assembled the genome of T. elegans using PacBio long-read sequencing, Illumina sequencing, and Hi-C methods. The genome assembly is 662.73 Mb in length with contig and scaffold N50 values of 1.15 Mb and 88.8 Mb, respectively. The genome contains 56.4% repeat sequences and 23,212 protein-coding genes were annotated. Phylogenomic analyses revealed that T. elegans diverged from the lineage leading to subfamily Pteromalinae (Nasonia vitripennis and Pteromalus puparum) approximately 110.5 million years ago. We identified 130 significantly expanded gene families, 34 contracted families, 248 fast-evolving genes, and 365 positively selected genes in T. elegans. Additionally, 260 olfactory receptors and 285 venom proteins were identified. This genome assembly provides valuable genetic bases for future investigations on evolution, molecular biology and application of T. elegans.