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

Experiment 1: Species

Research Question Will co-infecting species of fungi reduce BFOD’s potential as a biocontrol? Probably not.

Experiment 2: Strains

Research Question Will co-infecting strains of fungi reduce BFOD’s potential as a biocontrol? No.

Experiment 2 contd. Fast Virulent

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