Gypsy moth genome provides insights into flight capability and virus–host interactions

Abstract

Since its accidental introduction to Massachusetts in the late 1800s, the European gypsy moth (EGM; Lymantria dispar dispar) has become a major defoliator in North American forests. However, in part because females are flightless, the spread of the EGM across the United States and Canada has been relatively slow over the past 150 years. In contrast, females of the Asian gypsy moth (AGM; Lymantria dispar asiatica) subspecies have fully developed wings and can fly, thereby posing a serious economic threat if populations are established in North America. To explore the genetic determinants of these phenotypic differences, we sequenced and annotated a draft genome of L. dispar and used it to identify genetic variation between EGM and AGM populations. The 865-Mb gypsy moth genome is the largest Lepidoptera genome sequenced to date and encodes ∼13,300 proteins. Gene ontology analyses of EGM and AGM samples revealed divergence between these populations in genes enriched for several gene ontology categories related to muscle adaptation, chemosensory communication, detoxification of food plant foliage, and immunity. These genetic differences likely contribute to variations in flight ability, chemical sensing, and pathogen interactions among EGM and AGM populations. Finally, we use our new genomic and transcriptomic tools to provide insights into genome-wide gene-expression changes of the gypsy moth after viral infection. Characterizing the immunological response of gypsy moths to virus infection may aid in the improvement of virus-based bioinsecticides currently used to control larval populations.

Tracking invasions of a destructive defoliator, the gypsy moth (Erebidae: Lymantria dispar): Population structure, origin of intercepted specimens, and Asian introgression into North America

“…In total, we defined 13 clusters whose relationships mirror the geography across the Northern Hemisphere when viewed from above the North Pole (Figure 4b). Our findings support the overall population structure recovered from genomic SNP and microsatellite studies (Picq et al, 2017; Wu et al, 2015; Zhang et al, 2019) and offer new insight into fine‐scale regional structuring.…”

“…The separation was not recovered by genomic SNPs generated from laboratory‐reared colonies that no longer resemble wild populations (Picq et al, 2017). However, whole nuclear genome data from a few field‐collected specimens corroborated the split between U.S. and European samples (Zhang et al, 2019). Additionally, F ST values based on all nuclear loci between the North American and European populations were comparable to or even exceeded values among subspecies (Table 2, e.g., European L. d. dispar versus.…”

Genomics reveals the origins of ancient specimens

“…See Table S1 for complete specimen data. A piece of thoracic tissue from fresh specimens, and either the abdomen or a leg from pinned museum specimens were used for DNA extraction and genomic library preparation according to our protocols developed previously [21][22][23][24] . We used mate-pair libraries to assemble a reference genome of Hesperia colorado from a single wild-collected specimen, also accompanied by RNAseq for gene annotation.…”

Temporospatial modulation of Lymantria dispar immune system against an entomopathogenic fungal infection

“…Lymantria dispar is one of the most devastating defoliators worldwide, feeding on over 300 species of trees in coniferous and deciduous forests. 1,2 The caterpillar has three recognized sub-species: Lymantria dispar dispar, Lymantria dispar japonica, and Lymantria dispar asiatica. The latter two subspecies are generally considered as Asian gypsy moth (AGM).…”