Influence of Fungal Endophytes on Insect Herbivore Defense in Canada Wildrye (Elymus canadensis)
Dr. Thomas Bultman
In the past few decades, the relationship between Epichloë and Neotyphodium fungal endophytes and cool season grasses has gained increasing attention from botanists, mycologists, and ecologists alike. With hosts displaying traits that increase their competitive abilities and fitness when infected but occasionally suffering from the taxing fungal reproductive structures, an interesting relationship that is both mutualistic and parasitic can be observed. To determine how this dynamic association affects the variation of Epichloë infection frequency in Elymus canadensis populations across North America, seed samples from multiple populations were taken and tested for endophyte presence via PCR and gel-electrophoresis. Despite predictions, no significant relationship between infection frequency and latitude or longitude could be found, perhaps due to differences in biotic and abiotic factors between tested populations. Rhopalosiphum padi and Spodoptera frugiperda larvae were utilized to test how a diet of Epichloë elymi infected E. canadensis blade tissue affected insect herbivore performance. It was believed that since the E. elymi endophytes were capable of producing peramine and an intermediate ergot alkaloid that both insect species would suffer negative effects. While the S. frugiperda larvae showed less accumulation of dry weight when fed infected tissue, R. padi reproduction was not affected by such a diet. The reason for these results may be due to differences in sensitivity to peramine by the insect species.
A recommended citation will become available once a downloadable file has been added to this entry.