Weed Seed Predation Potential of Common Northwest Seed Predator

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Weed Seed Predation Potential of Common Northwest
Seed Predator

• Nicole Marshall
• Bio Resource Research
• -Environmental Molecular Toxicology
• -Plant Growth and Development
• Dr. Ed Peachey
• Department of Horticulture
• Oregon State University

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Background

• Economic Impacts of Weeds
• Hand weeding 500 - 10,000/ acre
• Several times a season
• Necessity for some crops
• Soil ecology undisturbed
• Herbicide treatments 0.50 - 77/ acre
• Large environmental impact
• Loss of biodiversity (vital organisms)
• Requires repeated treatments
• Leaves a chemical footprint
• Increase soil seed bank
• Tillage/ cultivation deeply bury
• weed seeds
• Unavailable for predation

www.ipm.iastate.edu/.../livingmulch.html
www.omafra.gov.on.ca/.../field/intro.htm
oceanworld.tamu.edu
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Background

• Pterostichus melanarius
• (Carabid beetle)

• 12 - 18 mm
• Common in cultivated soils
• Groundcover and
• sufficient moisture
• Nocturnal
• Predation of weed seeds
• Predation of aphids/ slugs

www.fcps.edu/.../common_black_ground_beetle.htm
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BackgroundWeed Species of Interest
Hairy Nightshade (Solanum sarrachoides)

• Red Root Pigweed (Amaranthus retroflexus)

www. Malag.aes.oregonstate.edu/wildflowers
www. Twig.tamu.edu/keyindex.htm
Ed Peachey
www.acornorganic.org (Steve Hurst-USDA)
www.cdfa.ca.gov
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Proso Millet (Panicum milaceum L.)
Wild Carrot Queen Annes Lace
(Daucus carota)
www.omafra.gov
www.solvinzankl.de/.../galerie/seed/index.htm
www.dianasgrove.com/aboutus/wildflowers.html
Oxeye Daisy (Chrysanthemum
leucantheumum)
www.mobot.org
www.solvinzankl.de/.../galerie/seed/index.htm
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Project Purpose

• Determine the efficacy and preference of
  seed predator populations on the available
  weed seed bank

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Hypothesis

• Carabid beetles show preferential predation of
  varying weed seed species

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Methods

• Evaluate seed predation potential
• of a key Northwest seed predator in the
• laboratory/greenhouse
• Varying media
• Varying weed seed species
• Individual predation ( , )
• Pterostichus melanarius collected at OSU
  Horticulture
• Research Farm and my garden using
  pitfall traps

http//users.skynet.be/fa213618/Pterostichus-melan
arius-01.jpg
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Methods

• Predation potential using varying media
• 5 varied media
• 6 beetles (density)
• 1 weed seed species
• Observe for isothiocyanate interference
• Observe behavior

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Results
Standard error bars
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Methods

• Carabid predation potential using varying weed
  seeds
• 1 media
• 6 beetles (density)
• 5 weed species
• Observe behavior

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Results
Seeds predated/ beetle/ day calculated using
(total seeds added) - (total seeds cached/
germinated) - (total seeds cached/germinated next
to Petri)
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Observations

• Burrowing behavior
• 45 to surface
• Cohabitation
• Under Petri platters (also seen in field)
• Caching behavior
• 1 - 2 from Petri platter
• Below surface in burrow
• Large millet seeds
• Imbibed seeds in soil

• Use of external digestion
• Hydrolytic enzymes
• Seeds (large seeds)
• Weak beetles
• Other edibles
• Preference for slug eggs over seeds
• Corn pollen grains
• Other behavior
• Surfaced for feedings

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Methods

• Beetle Hotel
• Individual carabid predation potential
• 1 beetle
• Sexed ,
• 1 weed species

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Results
Standard error bars
www.dkimages.com/discover/ Home/Animals/Invert...
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Observations

• Burrowing behavior
• Males head in
• Females hind end in
• Offspring protection
• Egg laid on surface
• Predation vs. caching
• Greater predation
• No caching

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Anticipated/ Future Outcomes

• Explore predation possibilities of other key
  seed predators
• Diverse biologically-based rotational strategies
  in cropping systems

• Conserve weed seed predators
• Reduce impact of invasive and economically
  significant weeds
• agricultural
• natural systems
• Reduce insecticide/ herbicide use
• conserve biological diversity
• increase weed seed predation

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Special Thanks..

• HHMI and Ernest and Pauline Jaworski
• Dr. Ed Peachey (mentor- Horticulture)
• Dr. Kevin Ahern (HHMI and Jaworski)
• Dr. Andy Moldenke (Entomologist)
• Dr. Dan McGrath (Entomologist)
• Alysia Greco (lab tech and assistant)
• Jessica Green (graduate student)