The Dynamics of Multiple Infection in Pyrenophora semeniperda Trevor Davis and Julie Beckstead, Gonzaga University, Department of Biology
Cheatgrass Invasion • Native to Eurasia • Transported in crop seed • Found in all U.S. states • Outcompetes natives • Alters fire cycle • Persistent seedbank
Pyrenophora semeniperda • Fungus: “BFOD” • Possible biocontrol • Naturally occurring • Seed Pathogen • Generalist • High infection and death rates in cheatgrass
Multiple Infections • Species and strains • Common in nature • Complicated: competition, toxins, genetics, growth rate, virulence. • Varied response • May affect BFOD
Research Questions • Will co-infecting species and strains of fungi reduce BFOD’s potential as a biocontrol? • What characteristics of two co-infectors’ relationship determines their response to one another?
Materials and Methods • Double inoculation • Species and strains • Blotter-plate bioassays • Analyze seeds and stromata
Research Question • Will co-infecting species of fungi reduce BFOD’s potential as a biocontrol? Probably not.
Research Question • Will co-infecting strains of fungi reduce BFOD’s potential as a biocontrol? No.
Experiment 2 contd. Virulent Fast
Research Question • What characteristics of two co-infectors’ relationship determines their response to one another? Virulence > Growth Rate
Conclusions • Co-infectors will not affect BFOD’s performance as a biocontrol. • Minimal (<30% impact) • Reduction in virulence offset by high inoculum load • Inoculation combined with other methods
Conclusions contd. • Co-infections may be useful • Combine strains for application • Example: virulent kills, fast-growing “eats” • Lessens risk of non-target death • Location-specific genotypes
Acknowledgements • Dr. Julie Beckstead • Dr. Susan Meyer • Dr. David Boose • Dr. Ann Kennedy • Sandra Dooley • Laura Street • Kellene Bergen • Lindsay Poston • Lauren Miller • Kristina Bair • Stephen Harrison