Effects of Nematode Genetic Diversity on Management of Potato Pests

CSANR Project 104

Status: Complete

Project Summary

Market forces are driving conventional Columbia Basin potato growers towards less-chemically-intensive pest management approaches, such as biological control. Insect-killing, entomopathogenic nematodes (EPNs), which live in the soil, have great potential for controlling insects with belowground life stages — such as the Colorado potato beetle. Our initial results suggest that EPNs can be incredibly abundant in WA potato fields where pesticide use is reduced, for example under organic management. We now know that two species, Heterorhabditis bacteriophera and Steinernema feltiae, dominate these EPN communities. However, the taxonomy of these nematodes is poorly understood, and our preliminary experiments suggest that genetic diversity within EPN species is as important for strong potato beetle control as is diversity at the species level. Here, we propose to combine a comprehensive collection of EPN strains from WA potato fields with cutting-edge genomics approaches for describing genetic diversity among these strains. Critically, field experiments will be used to relate genetic diversity within EPNs to the ability of these nematodes to control potato beetle pests in regions with varying climatic conditions. Our research will address two of the main 2012 priorities of the BioAg program, “Biological intensive and organic approaches to sustainable management of pests” and “Innovation and diversification to increase the resiliency and sustainability of farming and food systems in the face of climate change.” More fundamentally, we are fostering the development of the emerging field of “ecological genomics”, wherein the tools of modern molecular biology are used to understand the community ecology of natural pest control.

Annual Entries

2012

Principal Investigator: William Snyder
Progress Report: http://www.tfrec.wsu.edu/pdfs/P2792.pdf
Grant Amount: $39,876

2013

Principal Investigator: William Snyder
Additional Investigators: David Crowder
Axel Elling
Zhen Fu
Progress Report: http://csanr.wsu.edu/wp-content/uploads/2012/06/104Snyder.pdf

Publications

Jabbour, R, DW Crowder, EA Aultman and WE Snyder. 2011. Entomopathogen biodiversity increases host mortality. Biological Control 59:277‐283.
Crowder, DW, TD Northfield, R Gomulkiewicz and WE Snyder. 2012. Conserving and promoting evenness: Organic farming and fire‐based wildland management as case studies. Ecology 93:2001‐2007.

Additional Funds Leveraged

This project has allowed PI Snyder to develop molecular biology expertise in his laboratory, and in turn
this has allowed him to successfully compete for a large federal grant in this area. We learned this fall
that our USDA Organic Transitions (USDA‐ORG) proposal, which includes a molecular‐biology
component led by BIO‐Ag postdoc FU and PI Snyder, was funded at the full requested amount of $747,
955. Snyder is PI of the new USDA‐ORG grant. Also, BIO‐Ag co‐PIs Snyder, Elling and Fu will be
submitting a proposal to USDA‐NIFA’s Foundational Program this fall, with preliminary data from the
BIOAg project forming the core of this new proposal.

Impacts and Outcomes

∙        Short‐Term: We now have identified the species of EPN that occur in Washington organic potato
fields,  and  have  determined  that  significant  genetic  diversity  exists  within  these  populations.
Furthermore, combining genetically‐different EPN strains leads to higher mortality of pest insects. Thus,
the genetic diversity among EPNs that organic farming promotes, seems likely to improve natural pest
control.

∙        Intermediate‐Term: Our key intermediate‐term goal is to successfully compete for federal grant
funding to further investigate genetic differences among EPN species, identify genes that correspond to
important traits tied to a worm‐strains ability to kill hosts, and develop the means to search for these
traits in nematodes in potato fields. We next hope to begin the design and testing of bio‐pesticides that
combine beneficial and complementary nematode traits.

∙        Long‐Term: Our ultimate goal is to provide new commercial bio‐pesticides that effectively control
potato beetles, and to provide a model approach for understanding why natural enemies complement
one another that can be applied to other pests or cropping systems.