The Colorado potato beetle (Leptinotarsa decemlineata) is one of the most notorious insect pests of potatoes globally. Here, we generated a high-quality chromosome-level genome assembly of L. decemlineata using a combination of the PacBio HiFi sequencing and Hi-C scaffolding technologies. The genome assembly (−1,008 Mb) is anchored to 18 chromosomes (17 + XO), with a scaffold N50 of 58.32 Mb. It contains 676 Mb repeat sequences and 29,606 protein-coding genes. The chromosome-level genome assembly of L. decemlineata provides in-depth knowledge and will be a helpful resource for the beetle and invasive biology research communities.

The Colorado potato beetle is a notorious agricultural pest with remarkable adaptability and insecticide resistance. This study conducted comprehensive transcriptome analysis across multiple developmental stages and tissues, focusing on the cytochrome P450 monooxygenase gene family. Using RNA-seq data from 65 datasets, we identified significant transcriptional reprogramming during key developmental transitions, particularly from egg to first instar larva and from third instar larva to adult, reflecting critical biological processes, including feeding initiation and metamorphosis. We identified 3616 tissue-specific genes, with the testis exhibiting the highest transcriptional specialization (1182 genes). Genome-wide screening revealed 78 P450 genes distributed across four major clans with an uneven chromosomal distribution. Expression analysis demonstrated six distinct clusters with tissue and developmental stage-specific patterns. Evolutionary analysis identified five P450 genes under strong positive selection. Analysis of mRNA sequence polymorphisms revealed developmental stage and tissue-dependent patterns, with elevated mutation frequencies in early developmental stages and specific tissues. These distinct tissue and developmental stage-specific mutation patterns in P450 transcripts highlight the dynamic regulation of detoxification genes. Our findings advance the understanding of the molecular mechanisms underlying the beetle’s ecological success and provide valuable targets for developing novel pest management strategies.

The harlequin ladybird, Harmonia axyridis , is a predatory beetle used globally to control pests such as aphids and scale insects. Originating from East Asia, this species has become highly invasive since its introduction in the late 19th century to Europe and North America, posing a threat to local biodiversity. Intraguild predation is hypothesized to drive the success of this invasive species, but the underlying mechanisms remain unknown. In this study, a feeding assay revealed that while harlequin ladybirds survive feeding on seven-spotted ladybird eggs, the reverse is not true. However, seven-spotted ladybirds that had fed on harlequin ladybird eggs were able to survive the feeding assay when treated with penicillin. Microbiome sequencing and whole genome analysis of harlequin ladybird eggs revealed a newly discovered pathogenic bacterium strain named Serratia harmoniae. The median lethal concentration (LC50) of S. harmoniae was found to be 2.1 × 10 ⁵ times higher in the harlequin ladybird compared to the seven-spotted ladybird. The high tolerance observed in harlequin ladybirds was attributed to harmonine, specifically produced in the fat body of this species. Silencing three key genes in the harmonine biosynthesis pathway— Spidey , Sca2 , and Desat— reduced the production of the compound, leading to increased S. harmoniae levels and higher mortality. Treating RNAi-altered individuals with penicillin reversed this effect, successfully reducing S. harmoniae presence and increasing insect survival. Taken together, these findings demonstrate that S. harmoniae , a newly identified pathogenic bacterium carried by harlequin ladybirds, interacts with harmonine to confer an interspecies competitive advantage over native ladybird species in nonnative regions.

Insect metamorphosis involves significant changes in insect internal structure and is thus a critical focus of entomological research. Investigating the morphological transformation of internal structures is vital to understanding the origins of adult insect organs. Beetles are among the most species-rich groups in insects, but the development and transformation of their internal organs have yet to be systematically documented. In this study, we have acquired a comprehensive dataset that includes 27 detailed whole-body tomographic image sets of Harmonia axyridis, spanning from the prepupal to the pupal stages. Utilizing this data, we have created intricate 3D models of key internal organs, encompassing the brain, ventral nerve cord, digestive and excretion systems, as well as the body wall muscles. These data documented the transformation process of these critical organs and correlations between the origin of adult and larval organs and can be used to enhance the understanding of holometabolous adult organ genesis and offers a valuable reference model for investigating complete metamorphosis in insects.

Insect metamorphosis is a captivating aspect of animal research. To address the controversy regarding the developmental correspondence between hemimetabolous and holometabolous insects, we utilized non-destructive micro-computed tomography (CT) imaging and RNA-seq to examine wing growth and transcriptome profiles across juvenile stages in the Locusta migratoria, Harmonia axyridis, and Plutella xylostella, with distinct metamorphic strategies. Micro-CT revealed that over 88% of wing volume increase in ladybirds and moths occurs during the prepupal-pupal transition, similar to locust nymphs. Developmental transcriptome clustering demonstrated that gene expression patterns more closely resembled those between ladybird/moth prepupae/pupae and locust nymphs, whereas holometabolous larvae exhibited distinct profiles. Notably, gene expression specificity increased across juvenile stages with more recent species divergence. Genes highly expressed around the prepupal/pupal stages accumulated higher evolutionary rates. These integrated findings unveil commonalities in juvenile stage development among the locust, ladybird, and moth, providing insights into the evolution of metamorphosis within neopteran insects.