# Trio-sequencing Reveals High Germline Mutation Rates in the Colorado Potato Beetle (Leptinotarsa decemlineata)

## TL;DR

This study finds that the Colorado potato beetle has a high germline mutation rate, which may explain its rapid evolution of pesticide resistance.

## Contribution

The paper provides the first quantification of germline mutation rates in beetles and links it to evolutionary dynamics.

## Key findings

- The germline mutation rate in CPB is 5.8 × 10−9 per site per generation, twice the median for insects.
- Mutation rate in insects is positively associated with genome-wide GC content.
- One CPB female's brood can introduce nearly 141 new mutations into coding regions each generation.

## Abstract

Germline mutation rates are fundamental to evolution, yet they remain unquantified for beetles (Coleoptera), the most speciose order including major pests. We sequenced genomes from 16 trios of the Colorado potato beetle (Leptinotarsa decemlineata, CPB)—a pest that has evolved resistance to many insecticides. We estimated a germline mutation rate of 5.8 × 10−9 (95% CI: 4.7 × 10−9, 7.2 × 10−9) per site per generation in CPB, a rate 2-fold higher than the median for other insects. Across 13 insect species, mutation rate was positively associated with genome-wide GC content (PGLS). The increased mutation rate in CPB is also consistent with drift-barrier expectations. Based on this mutation rate and the beetle’s fecundity, we estimate that the brood from just one CPB female can introduce nearly 141 new mutations into the coding regions each generation. These findings inform CPB’s rapid pesticide resistance evolution and fill a key gap in arthropod genomics and evolution.