Submitted to: Society for Invertebrate Pathology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 4/17/2011
Publication Date: 8/5/2011
Citation: Rowley, D.L., Popham, H.J., Harrison, R.L. 2011. Genetic variation, and biological activity of nucleopolyhedrovirus samples from larvae Heliothis virescens, Helicoverpa zea, and Helicoverpa armigera. Society for Invertebrate Pathology Annual Meeting. pp.62-63.
Technical Abstract: To assess the diversity and relationships of baculoviruses found in insects of the heliothine pest complex, a PCR-based method was used to classify 90 samples of nucleopolyhedrovirus (NPV; Baculoviridae: Alphabaculovirus) obtained worldwide from larvae of Heliothis virescens (Fabricius), Helicoverpa zea (Boddie), and Helicoverpa armigera (Hübner). Partial nucleotide sequencing and phylogenetic analysis of three highly conserved genes (lef-8, lef-9, and polh) indicated that 67 of these samples contained isolates of the H. zea-H. armigera single nucleopolyhedrovirus (Hz/HaSNPV) species group. Eighteen of the samples contained isolates of a multiple NPV from H. armigera, HearMNPV, and five of the samples contained isolates of Autographa californica MNPV (AcMNPV). The Hz/HearSNPV isolates occurred in two separate groups of HearSNPV variants and a third group of HzSNPV variants; this organization was confirmed by sequencing and analysis of an additional seven loci (orf5/orf5b, hr3-orf62, orf26, orf79, orf124/orf117a, orf42, and a part of the region between hr2 and hr3). Some of the samples contained isolates of more than one virus. In bioassays of a selection of isolates against H. zea, the commercially available Gemstar isolate of HzSNPV killed larvae faster than most other Hz/HaSNPV and HearMNPV isolates. Gemstar and two HearMNPV isolates exhibited significantly higher LC50s than the Hz/HearSNPV isolates tested. This study expands significantly on what we know about the variation of heliothine NPV populations and provides novel information on the distinct groups in which these NPVs occur.