Contrasting patterns of genetic structure and population demography in two Dicraeus species feeding on bamboo flowers in Japan.

This article focuses on the phylogenetic relationships and population genetic structures of two bamboo-feeding insect species, *Dicraeus phyllostachyus* and *Dicraeus nartshukae*, in Japan, leveraging a recent nationwide mass flowering event of bamboo. Using mitochondrial cytochrome oxidase I (COI) gene sequencing and genome-wide single-nucleotide polymorphisms (SNPs) detected by multiplexed inter-simple sequence repeat genotyping by sequencing (MIG-seq), the study found genetic similarity across wide geographic ranges for both species but contrasting population structures: *D. phyllostachyus* showed no clear genetic clustering and evidence of recent population expansion, while *D. nartshukae* exhibited distinct northern and southern genetic groups with limited gene flow between them. The findings suggest that bamboo mass flowering events influence the genetic structure of these florivorous insects through trophic interactions and highlight the importance of comparing closely related species to understand outbreak dynamics and evolutionary history in phytophagous insects.