Genome of the webworm Hyphantria cunea unveils genetic adaptations supporting its rapid invasion and spread

Abstract

Background: The fall webworm Hyphantria cunea is an invasive and polyphagous defoliator pest that feeds on nearly any type of deciduous tree worldwide. The silk web of H. cunea aids its aggregating behavior, provides thermal regulation and is regarded as one of causes for its rapid spread. In addition, both chemosensory and detoxification genes are vital for host adaptation in insects. Results: Here, a high-quality genome of H. cunea was obtained. Silk-web-related genes were identified from the genome, and successful silencing of the silk protein gene HcunFib-H resulted in a significant decrease in silk web shelter production. The CAFE analysis showed that some chemosensory and detoxification gene families, such as CSPs, CCEs, GSTs and UGTs, were expanded. A transcriptome analysis using the newly sequenced H. cunea genome showed that most chemosensory genes were specifically expressed in the antennae, while most detoxification genes were highly expressed during the feeding peak. Moreover, we found that many nutrient-related genes and one detoxification gene, HcunP450 (CYP306A1), were under significant positive selection, suggesting a crucial role of these genes in host adaptation in H. cunea. At the metagenomic level, several microbial communities in H. cunea gut and their metabolic pathways might be beneficial to H. cunea for nutrient metabolism and detoxification, and might also contribute to its host adaptation. Conclusions: These findings explain the host and environmental adaptations of H. cunea at the genetic level and provide partial evidence for the cause of its rapid invasion and potential gene targets for innovative pest management strategies.

Genome sequence and silkomics of the spindle ermine moth, Yponomeuta cagnagella, representing the early diverging lineage of the ditrysian Lepidoptera

“…Yet, both measurements suggest that genome size of Y. cagnagella is larger than average (1C = 430 Mb) or the ancestral size (1C = 489 Mb) proposed for Lepidoptera 36 . This high value can be explained by expansion of repeats, as nearly half of the assembly was annotated as repetitive elements, and/or by large intron size as suggested by Chen et al 37 in the webworm Hyphantria cunea . The primary genome assembly length was 978.3 Mb, which was significantly larger than expected genome size and probably the result of haplotype retention caused by high levels of heterozygosity revealed in the sample by k-mer analysis.…”

RNAi-Mediated Silencing of the Chitinase 5 Gene for Fall Webworm (Hyphantria cunea) Can Inhibit Larval Molting Depending on the Timing of dsRNA Injection

“…The identification of novel management strategies is urgently required to control this pest. In recent years, RNAi-based pest management has been increasingly studied as a novel insect control strategy and the publication of genome and transcriptome sequencing for H. cunea also provided a molecular basis for H. cunea control [ 20 , 21 , 22 ]. However, potentially effective genetic targets and innovative strategies to control this invasive pest are still lacking.…”

Caterpillars Detoxify Diterpenoid from Nepeta stewartiana by the Molting Hormone Gene CYP306A1

“…litura larvae (Figure ). Moreover, a few studies have found that expression levels of CYP306A1 are elevated after insects have ingested certain plant-specialized metabolic products; however, this evidence is confined to transcript levels in vivo, and evidence to verify the connection between CYP306A1 and detoxification is lacking. CYP306A1 has also been found to metabolize 7-ethoxy coumarin and 7-benzyloxymethoxy resorufin in the past .…”