Phylogenomic analysis and molecular identification of true fruit flies.

The family Tephritidae in the order Diptera, known as true fruit flies, are agriculturally important insect pests. However, the phylogenetic relationships of true fruit flies, remain controversial. Moreover, rapid identification of important invasive true fruit flies is essential for plant quarantine but is still challenging. To this end, we sequenced the genome of 16 true fruit fly species at coverage of 47-228×. Together with the previously reported genomes of nine species, we reconstructed phylogenetic trees of the Tephritidae using benchmarking universal single-copy ortholog (BUSCO), ultraconserved element (UCE) and anchored hybrid enrichment (AHE) gene sets, respectively. The resulting trees of 50% taxon-occupancy dataset for each marker type were generally congruent at 88% nodes for both concatenation and coalescent analyses. At the subfamily level, both Dacinae and Trypetinae are monophyletic. At the species level, Bactrocera dorsalis is more closely related to Bactrocera latifrons than Bactrocera tryoni. This is inconsistent with previous conclusions based on mitochondrial genes but consistent with recent studies based on nuclear data. By analyzing these genome data, we screened ten pairs of species-specific primers for molecular identification of ten invasive fruit flies, which PCR validated. In summary, our work provides draft genome data of 16 true fruit fly species, addressing the long-standing taxonomic controversies and providing species-specific primers for molecular identification of invasive fruit flies.

Unraveling the complex evolutionary history of lepidopteran chromosomes through ancestral chromosome reconstruction and novel chromosome nomenclature.

BACKGROUND: Lepidoptera is one of the most species-rich animal groups, with substantial karyotype variations among species due to chromosomal rearrangements. Knowledge of the evolutionary patterns of lepidopteran chromosomes still needs to be improved. RESULTS: Here, we used chromosome-level genome assemblies of 185 lepidopteran insects to reconstruct an ancestral reference genome and proposed a new chromosome nomenclature. Thus, we renamed over 5000 extant chromosomes with this system, revealing the historical events of chromosomal rearrangements and their features. Additionally, our findings indicate that, compared with autosomes, the Z chromosome in Lepidoptera underwent a fast loss of conserved genes, rapid acquisition of lineage-specific genes, and a low rate of gene duplication. Moreover, we presented evidence that all available 67 W chromosomes originated from a common ancestor chromosome, with four neo-W chromosomes identified, including one generated by fusion with an autosome and three derived through horizontal gene transfer. We also detected nearly 4000 inter-chromosomal gene movement events. Notably, Geminin is transferred from the autosome to the Z chromosome. When located on the autosome, Geminin shows female-biased expression, but on the Z chromosome, it exhibits male-biased expression. This contributes to the sexual dimorphism of body size in silkworms. CONCLUSIONS: Our study sheds light on the complex evolutionary history of lepidopteran chromosomes based on ancestral chromosome reconstruction and novel chromosome nomenclature.

A chromosome-level genome assembly of tomato pinworm, Tuta absoluta.

The tomato pinworm, Tuta absoluta, or Phthorimaea absouta, is native to South America, but quickly spread to other regions of world, including Europe, Africa, and Asia, devastating to global tomato production. However, a lack of high-quality genome resources makes it difficult to understand its high invasiveness and ecological adaptation. Here, we sequenced the genome of the tomato pinworm using Nanopore platforms, yielding a genome assembly of 564.5 Mb with contig N50 of 3.33 Mb. BUSCO analysis demonstrated that this genome assembly has a high-level completeness of 98.0% gene coverage. In total, 310 Mb are repeating sequences accounting for 54.8% of genome assembly, and 21,979 protein-coding genes are annotated. Next, we used the Hi-C technique to anchor 295 contigs to 29 chromosomes, yielding a chromosome-level genome assembly with a scaffold N50 of 20.7 Mb. In sum, the high-quality genome assembly of the tomato pinworm is a useful gene resource that contributes to a better understanding of the biological characteristics of its invasiveness and will help in developing an efficient control policy.