Chromosome-level genome of black cutworm provides novel insights into polyphagy and seasonal migration in insects

Background: The black cutworm, Agrotis ipsilon, is a serious global underground pest. Its distinct phenotypic traits, especially its polyphagy and ability to migrate long distances, contribute to its widening distribution and increasing difficulty of control. However, knowledge about these traits is still limited. Results: We generated a high-quality chromosome-level assembly of A. ipsilon using PacBio and Hi-C technology with a contig N50 length of similar to 6.7 Mb. Comparative genomic and transcriptomic analyses showed that detoxification-associated gene families were highly expanded and induced after insects fed on specific host plants. Knockout of genes that encoded two induced ABC transporters using CRISPR/Cas9 significantly reduced larval growth rate, consistent with their contribution to host adaptation. A comparative transcriptomic analysis between tethered-flight moths and migrating moths showed expression changes in the circadian rhythm gene AiCry2 involved in sensing photoperiod variations and may receipt magnetic fields accompanied by MagR and in genes that regulate the juvenile hormone pathway and energy metabolism, all involved in migration processes. Conclusions: This study provides valuable genomic resources for elucidating the mechanisms involved in moth migration and developing innovative control strategies.

Automated summary

This study generated a high-quality chromosome-level assembly of Agrotis ipsilon and found that detoxification-associated gene families were highly expanded and induced after feeding on specific host plants. Knockout of genes encoding induced ABC transporters significantly reduced larval growth rate, indicating their contribution to host adaptation. Comparative transcriptomic analysis also revealed expression differences between tethered-flight moths and migrating moths, involving genes related to sensing photoperiod variations, magnetic fields, and migration processes.