Chromosome-level genome assembly of the common straight swift, Parnara guttata, provides insights into adaptive evolution on its rice host.

Background

The common straight swift, Parnara guttata, a leaf-feeding rice pest, is widely distributed in Asia, particularly in China, Japan and South Korea. The larvae feed on leaves and bind them together into rolled shelters, reducing photosynthesis and rice heading. However, the lack of a high-quality genome has limited investigation into environmental adaptation in P. guttata and the development of integrated pest management strategies.

Results

Here, we generated a chromosome-level reference genome for P. guttata by integrating PacBio HiFi long reads with Hi-C technology. The final assembly was 484.88 Mb with a scaffold N50 of 32.96 Mb, and 99.41% of the sequences were anchored to 16 chromosomes. BUSCO analysis showed a completeness of 99.2%. Repetitive sequences accounted for 36.9% of the genome, and 15 241 protein-coding genes were annotated. Comparative genomic analyses indicated expansions in gene families related to muscle development, lipid metabolism, detoxification and immunity. We also found tandem expansions of CYP6/CYP9 and UGT33/UGT39/UGT40 genes, together with positive selection in ATP-binding cassette transporters. Midgut transcriptome analysis further identified several highly expressed candidate detoxification genes, including tandemly duplicated P450 and UGT genes, as well as PgCCEg206. By contrast, fewer chemosensory genes were identified in P. guttata than the other lepidopteran rice pests.

Conclusion

The high-quality P. guttata genome provides a valuable resource for studying skipper butterfly evolution and offers new insights into genomic features potentially associated with detoxification and adaptation to its Poaceae host. © 2026 Society of Chemical Industry.