Chromosome-scale genome of the polyphagous pest Anastrepha ludens (Diptera: Tephritidae) provides insights on sex chromosome evolution in Anastrepha

The Mexican fruit fly, Anastrepha ludens, is a polyphagous true fruit fly (Diptera: Tephritidae) considered 1 of the most serious insect pests in Central and North America to various economically relevant fruits. Despite its agricultural relevance, a high-quality genome assembly has not been reported. Here, we described the generation of a chromosome-level genome forthe A. ludens using a combination of PacBio high fidelity long-reads and chromatin conformation capture sequencing data. The final assembly consisted of 140 scaffolds (821 Mb, N50 = 131 Mb), containing 99.27% complete conserved orthologs (BUSCO) for Diptera. We identified the sex chromosomes using 3 strategies: (1) visual inspection of Hi-C contact map and coverage analysis using the HiFi reads, (2) synteny with Drosophila melanogaster, and (3) the difference in the average read depth of autosomal vs sex chromosomal scaffolds. The X chromosome was found in 1 major scaffold (100 Mb) and 8 smaller contigs (1.8 Mb), and the Y chromosome was recovered in 1 large scaffold (6.1 Mb) and 35 smaller contigs (4.3 Mb). Sex chromosomes and autosomes showed considerable differences of transposable elements and gene content. Moreover, evolutionary rates of orthologs of A. ludens and Anastrepha obliqua revealed a faster evolution of X-linked, compared with autosome-linked, genes, consistent with the faster-X effect, leading us to new insights on the evolution of sex chromosomes in this diverse group of flies. This genome assembly provides a valuable resource for future evolutionary, genetic, and genomic translational research supporting the management of this important agricultural pest.