# A muscle-centered hierarchical breakdown underlies flight loss during silkworm domestication

## TL;DR

The study shows how silkworms lost flight through muscle-related genetic changes, offering insights into pest control.

## Contribution

The paper identifies a conserved, muscle-centered genetic module responsible for flight loss in Lepidoptera.

## Key findings

- Flight loss in Bombyx mori is due to a breakdown in flight muscle cells and energy production.
- Disruption of the Yki gene worsens wing defects in Bombyx mori.
- The same genetic module is conserved in Helicoverpa armigera, suggesting a target for pest control.

## Abstract

Recurrent loss of complex traits such as insect flight offers insights into evolutionary regression, as seen in Bombyx mori domestication from its flight-capable ancestor B. mandarina. By integrating single-cell and spatial transcriptomics of developing flight organs in both Bombyx species, we reveal that flight loss occurs through a coordinated breakdown centered on flight muscle cells. This stems from disintegration of a multi-tiered genetic module with three interconnected components: failures in mitochondrial energy production (e.g., COX3/ND1), wing vein patterning (involving Dally/CtBP), and flight muscle specification (controlled by Yki). Knocking down key components in B. mandarina induced flightlessness, and perturbing the Hippo effector Yki in B. mori exacerbated wing defects, together highlighting the pathway’s dosage-sensitive nature. Notably, this muscle-centric module is conserved in the migratory pest Helicoverpa armigera, where its disruption similarly impaired flight. Our work establishes trait degeneration as a muscle-centered collapse and identifies a conserved target for precision pest control.

•Single-cell and spatial atlas reveals a muscle-centric basis for flight loss in Lepidoptera•Flight degeneration follows hierarchical disintegration of a three-tiered genetic module•Conserved flight module in Helicoverpa armigera informs precision pest control

Single-cell and spatial atlas reveals a muscle-centric basis for flight loss in Lepidoptera

Flight degeneration follows hierarchical disintegration of a three-tiered genetic module

Conserved flight module in Helicoverpa armigera informs precision pest control

Entomology; Molecular biology; Evolutionary biology; Transcriptomics