Location: Wheat, Sorghum and Forage ResearchTitle: Evaluation of tetraploid switchgrass populations (Panicum virgatum L.) for host suitability and differential resistance to four cereal aphids Author
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/3/2013
Publication Date: 2/1/2014
Publication URL: http://handle.nal.usda.gov/10113/58368
Citation: Koch, K.G., Fithian, R., Heng-Moss, T.M., Bradshaw, J.D., Sarath, G. 2014. Evaluation of tetraploid switchgrass populations (Panicum virgatum L.) for host suitability and differential resistance to four cereal aphids. Journal of Economic Entomology. 107:424-431. Interpretive Summary: Large scale deployment of switchgrass for bioenergy purposes will require detailed understanding of a number of factors that can affect the sustainability of crop production. One factor that can be expected to play a detrimental role in harvestable yields of biomass is insects. There is limited information on the responses of switchgrass plants to feeding by piercing-sucking insects such as aphids. In this work the relative resistance or susceptibility of several switchgrasses to herbivory by a range of different cereal aphids was evaluated. Results indicate that some switchgrass display broad resistance to several aphids, whereas others are more susceptible to injury from specific aphids such as greenbugs and the yellow sugarcane aphid. These results will be foundational to continuing studies to understand cellular mechanisms underlying differential resistance in switchgrass germplasm that can be utilized for bioenergy.
Technical Abstract: Switchgrass, Panicum virgatum L., is being developed as a bioenergy feedstock. The potential for large-scale production has encouraged its evaluation as a host for important grass pests. Eight no-choice studies were performed for two developmental stages of two switchgrass cultivars (Kanlow and Summer) and two experimental strains, KxS, and SxK produced by reciprocal mating of these cultivars followed by selection for high yield. Plants were evaluated for host suitability and damage differences to herbivory by four important cereal aphids, Sipha flava (Forbes), Schizaphis graminum (Rondani) (biotype I), Rhopalosiphum padi (L.), and Diuraphis noxia (Mordvilko). All switchgrasses were found to be unsuitable feeding and reproductive hosts to R. padi and D. noxia, which were unable to establish on the plants. However, both S. flava and S. graminum were able to establish on all switchgrasses tested. Differential levels of resistance to S. flava and S. graminum were detected among the switchgrasses by both cumulative aphid days (CAD) and plant damage ratings. Kanlow was consistently rated as highly resistant based on CAD and damage ratings for both aphid species, while Summer was consistently among the most susceptible to both aphids at both developmental stages, with relatively high damage ratings. The resistance of the KxS and SxK populations in relationship to their Summer and Kanlow parents indicted that they inherited some resistance to S. graminum and S. flava from their Kanlow parent. These studies provide valuable baseline information concerning the host suitability of switchgrass to four cereal aphids and the plant-insect interactions within a system that has been largely overlooked and indicate that there are genetic differences among switchgrass populations for resistance to some insects.