Chromosome scale genomes of two invasive Adelges species enable virtual screening for selective adelgicides

Authors: GLENDENNING, ADAM - University Of Connecticut; STEPHENS, COLE - University Of Michigan Medical School; VURUPUTOOR, VIDYA - University Of Connecticut; STERN, DAVID - Howard Hughes Medical Institute; MATHERS, TC - Wellcome Trust Sanger Institute; HOGENHOUT, SA - John Innes Center; CHAGANTI, TESKO - University Of Michigan Medical School; PAULOSKI, NICOLE - University Of Connecticut; CERNAK, TIM - University Of Michigan Medical School; WEGRZYN, JILL - University Of Connecticut; Fetter, Karl

Submitted to: G3: Genes, Genomes, Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/21/2025
Publication Date: 10/3/2025
Citation: Glendenning, A., Stephens, C., Vuruputoor, V., Stern, D., Mathers, T., Hogenhout, S., Chaganti, T., Pauloski, N., Cernak, T., Wegrzyn, J., Fetter, K.C. 2025. Chromosome scale genomes of two invasive Adelges species enable virtual screening for selective adelgicides. G3: Genes, Genomes, Genetics. https://doi.org/10.1093/g3journal/jkaf232.
DOI: https://doi.org/10.1093/g3journal/jkaf232

Interpretive Summary: Adelgids are important pests of conifers globally. The Hemlock Woolly Adelgid (Adelges tsugae) evolved in eastern Asia and was introduced into eastern North American forests in the early 20th century. The Hemlock Woolly Adelgid has proven to be a major pest of the native eastern hemlock tree (Tsuga canadensis), and is pushing nearly all populations of the eastern hemlock towards collapse. The eastern spruce gall adelgid (Adelges abietis) is a pest of multiple species of spruce across North America. Eastern spruce gall adelgids weakens the immune system of host trees, and often increase colonization of other pests and pathogens on the host, increasing host mortality. Reference genomes provide researches a detailed understanding of genes and genetic regulatory networks, enabling the discovery of new management techniques in pest species. Both species of adelgid lacked reference genomes, and this work provides two high quality genomes. Using comparative genomic techniques, we probed the evolutionary history of each genome. We investigated key enzymes for the physiology of adelgids in order to guide potential selection of insecticides for management. The sequence data, reference genome assemblies, and the genome annotations were uploaded to NCBI's public data archives to enable future research in this important pest-host system.

Technical Abstract: Two invasive hemipteran adelgids cause widespread damage to North American conifers. Adelges tsugae (the hemlock woolly adelgid) has decimated Tsuga canadensis and Tsuga caroliniana (the Eastern and Carolina hemlocks, respectively). A. tsugae was introduced from East Asia and reproduces parthenogenetically in North America, where it can kill trees rapidly. A. abietis, introduced from Europe, makes “pineapple” galls on several North American spruce species, and weakens trees, increasing their susceptibility to other stresses. Broad-spectrum insecticides that are often used to control adelgid populations can have off-target impacts on beneficial insects and the development of more selective chemical treatments could improve control methods and minimize ecological damage. Whole genome sequencing was performed on both species to aid in development of targeted pest control solutions and improve species conservation. The assembled A. tsugae and A. abietis genomes are 220.75 Mbp and 253.16 Mbp, respectively, each consisting of nine chromosomes and both genomes are over 96% complete based on BUSCO assessment. Genome annotation identified 11,424 and 14,118 protein-coding genes in A. tsugae and A. abietis, respectively. Comparative analysis across 29 Hemipteran species and 14 arthropod outgroups identified 31,666 putative gene families. Gene family expansions in A. abietis included ABC transporters and carboxypeptidases involved in carbohydrate metabolism, while both species showed contractions in core histone families and oxidoreductase pathways. Gene family expansions in A. tsugae highlighted families associated with the regulation of cell differentiation and development (survival motor protein, SMN; juvenile hormone acid methyltransferase JHAMT) as well as those that may be involved in the suppression of plant immunity (clip domain serine protease-D, CLIPD; Endoplasmic reticulum aminopeptidase 1, ERAP1). Among the analyzed gene families, Nicotinic acetylcholine receptors (nAChRs) maintained consistent copy numbers and structural features across species, a finding particularly relevant given their role as targets for current forestry management insecticides. Detailed phylogenetic analysis of nAChR subunits across adelgids and other ecologically important insects revealed remarkable conservation in both sequence composition and predicted structural features, providing crucial insights for the development of more selective pest control strategies.