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
Background
Economic Impacts of Weeds:
Hand weeding: $500 - $10,000/ acre
 Several times
a season
 Necessity for some crops
 Soil ecology undisturbed
www.ipm.iastate.edu/.../livingmulch.html
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
www.omafra.gov.on.ca/.../field/intro.htm
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.

weed seeds
 Unavailable for predation
oceanworld.tamu.edu
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
Background
Weed Species of Interest
Red Root Pigweed
(Amaranthus retroflexus)
www. Malag.aes.oregonstate.edu/wildflowers
Hairy Nightshade
(Solanum sarrachoides)
www. Twig.tamu.edu/keyindex.htm
Ed Peachey
www.acornorganic.org (Steve Hurst-USDA)
www.cdfa.ca.gov
Proso Millet
(Panicum milaceum L.)
Wild Carrot
Queen Anne’s 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
Project Purpose
 Determine the efficacy and
preference of seed predator
populations on the available weed
seed bank
Hypothesis
Carabid beetles show preferential
predation of varying weed seed species
Methods
Evaluate seed predation potential
 of a key Northwest seed predator in the
 laboratory/greenhouse
Varying media
Varying weed seed species
Individual predation ( , )
http://users.skynet.be/fa213618/P
terostichus-melanarius-01.jpg

Pterostichus melanarius collected at OSU
Horticulture
Research Farm and my garden using pitfall traps

Methods
Predation potential
using varying media
5 varied media
6 beetles (density)
1 weed seed species
Observe for
isothiocyanate
interference
Observe behavior

Results
*Standard error bars
Methods
Carabid predation
potential using
varying weed seeds
1 media
6 beetles (density)
5 weed species
Observe behavior
Results
*Seeds predated/ beetle/ day calculated using
(total seeds added) - (total seeds cached/ germinated) - (total seeds cached/germinated next to Petri)
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
Methods
 “Beetle Hotel”
Individual carabid
predation potential
1 beetle
Sexed
,
1 weed species
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Results
*Standard error bars
www.dkimages.com/discover/ Home/Animals/Invert...
Observations
Burrowing behavior:
Males head in
Females hind end in
 Offspring protection
 Egg
laid on surface
Predation vs. caching:
Greater predation
No caching
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
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)