A transcriptome survey spanning life stages and sexes of the Harlequin bug, Murgantia histrionica

Authors: Sparks, Michael; RHOADES, JOSHUA - University Of Maryland; NELSON, DAVID - University Of Tennessee; Kuhar, Daniel; LANCASTER, JASON - Virginia Polytechnic Institution & State University; LEHNER, BRYAN - Virginia Polytechnic Institution & State University; THOLL, DOROTHEA - Virginia Polytechnic Institution & State University; Weber, Donald; Gundersen-Rindal, Dawn

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/18/2017
Publication Date: 5/25/2017
Citation: Sparks, M., Rhoades, J.H., Nelson, D.R., Kuhar, D.J., Lancaster, J., Lehner, B., Tholl, D., Weber, D.C., Gundersen, D.E. 2017. A transcriptome survey spanning life stages and sexes of the Harlequin bug, Murgantia histrionica. Insects. doi: 10.3390/insects8020055.

Interpretive Summary: The harlequin bug, Murgantia histrionica, is an invasive species and a very destructive pest of such cole crops as cabbage, cauliflower and broccoli, in particular among farming operations in southern states of the continental United States. Outbreaks of this insect often occur following mild winters. To maintain this pest’s population size at manageable levels without excessive use of synthetic chemical pesticides, it is desirable to develop environmentally friendly biomolecular control methods. These in turn depend on the availability of reliable gene sequence data to identify candidate genes to target for disruption in the organism. This study reports on the first collection of such data generated specifically for the harlequin bug. In it, a number of gene families implicated in chemical insecticide detoxification and resistance are characterized, and a number of genes having remarkable expression level differences between juvenile and adult insects are identified. These results will directly assist in producing effective, biologically-based biocontrol methods for this nuisance species and will be used by scientists and those interested in stink bug biocontrol.

Technical Abstract: The harlequin bug, Murgantia histrionica (Hahn), is an agricultural pest in the continental United States, particularly in southern states. Reliable gene sequence data are especially useful to the development of species-specific, environmentally friendly molecular biopesticides and effective biolures for this insect. Here, mRNAs were sampled from whole insects at the 2nd and 4th nymphal instars, as well as sexed adults, and sequenced using Illumina RNA-Seq technology. A global assembly of these data identified 72,540 putative unique transcripts bearing high levels of similarity to transcripts identified in other taxa, with over 99% of conserved single-copy orthologs among insects being detected. Gene ontology and protein family analyses were conducted to explore the functional potential of the harlequin bug’s gene repertoire, and phylogenetic analyses were conducted on gene families germane to xenobiotic detoxification, including glutathione S-transferases, carboxylesterases and cytochrome P450s. Genic content in harlequin bug was compared with that of the closely related invasive pest, the brown marmorated stink bug, Halyomorpha halys (Stål). Quantitative analyses of harlequin bug gene expression levels identified genes differentially expressed between life stages and/or sexes, and a number of these were experimentally validated using quantitative real-time PCR.