| Title: | Plant genotype and induced defenses affect the productivity of an insect-killing obligate viral pathogen |
| Author(s): | Shikano I; McCarthy EM; Elderd BD; Hoover K; |
| Address: | "Department of Entomology and Center for Chemical Ecology, Pennsylvania State University, University Park, PA 16802, USA. Electronic address: ius15@psu.edu. Department of Chemistry, Indiana University, Bloomington, IN 47404, USA. Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA. Department of Entomology and Center for Chemical Ecology, Pennsylvania State University, University Park, PA 16802, USA" |
| DOI: | 10.1016/j.jip.2017.05.001 |
| ISSN/ISBN: | 1096-0805 (Electronic) 0022-2011 (Linking) |
| Abstract: | "Plant-mediated variations in the outcomes of host-pathogen interactions can strongly affect epizootics and the population dynamics of numerous species, including devastating agricultural pests such as the fall armyworm. Most studies of plant-mediated effects on insect pathogens focus on host mortality, but few have measured pathogen yield, which can affect whether or not an epizootic outbreak occurs. Insects challenged with baculoviruses on different plant species and parts can vary in levels of mortality and yield of infectious stages (occlusion bodies; OBs). We previously demonstrated that soybean genotypes and induced anti-herbivore defenses influence baculovirus infectivity. Here, we used a soybean genotype that strongly reduced baculovirus infectivity when virus was ingested on induced plants (Braxton) and another that did not reduce infectivity (Gasoy), to determine how soybean genotype and induced defenses influence OB yield and speed of kill. These are key fitness measures because baculoviruses are obligate-killing pathogens. We challenged fall armyworm, Spodoptera frugiperda, with the baculovirus S. frugiperda multi-nucleocapsid nucleopolyhedrovirus (SfMNPV) during short or long-term exposure to plant treatments (i.e., induced or non-induced genotypes). Caterpillars were either fed plant treatments only during virus ingestion (short-term exposure to foliage) or from the point of virus ingestion until death (long-term exposure). We found trade-offs of increasing OB yield with slower speed of kill and decreasing virus dose. OB yield increased more with longer time to death and decreased more with increasing virus dose after short-term feeding on Braxton compared with Gasoy. OB yield increased significantly more with time to death in larvae that fed until death on non-induced foliage than induced foliage. Moreover, fewer OBs per unit of host tissue were produced when larvae were fed induced foliage than non-induced foliage. These findings highlight the potential importance of plant effects, even at the individual plant level, on entomopathogen fitness, which may impact epizootic transmission events and host population dynamics" |
| Keywords: | Animals Genotype Host-Pathogen Interactions/*physiology Nucleopolyhedroviruses/*pathogenicity Plant Immunity Soybeans/*genetics Spodoptera/*virology Biological control Epizootic Glycine max Parasite fitness Spodoptera frugiperda multiple nucleocapsid nucl; |
| Notes: | "MedlineShikano, Ikkei McCarthy, Elizabeth M Elderd, Bret D Hoover, Kelli eng 2017/05/10 J Invertebr Pathol. 2017 Sep; 148:34-42. doi: 10.1016/j.jip.2017.05.001. Epub 2017 May 5" |
