Download Abundance of Epigeal Arthropods in Organic Feed

Abundance of Epigeal Arthropods in Organic Feed and Forage Systems
Christina A. Mullen and Mary E. Barbercheck
Department of Entomology, Pennsylvania State University, University Park, PA 16802 E-mail: [email protected]
Introduction
The soil surface (epigeal) arthropod community can
mediate critical agroecosystem processes, e.g.,
decomposition, N-mineralization, and biological control.
We expect to find the greatest number of epigeal
arthropods in systems with minimal disturbance (i.e.,
tillage) and high soil quality (e.g., SOM). Tillage can
directly kill ground-dwelling arthropods, and high SOM can
subsidize the soil food web, providing resources to support
arthropod predators. Here we present results for early
season arthropods in conventionally-tilled and no-till corn
in the Starts 1 (2010) and 2 (2011) of the RAMP
experiment.
Methods
We randomly placed three pitfall traps in
each treatment plot. The traps were
collected after 72 hr and returned to the lab,
Bird’s eye view of
where arthropods were removed, preserved
a pitfall trap in the
and identified to arthropod order and family.
field.
Ground beetles (Carabidae) were identified
down to species.
Common Soil Surface Arthropods in Organic Forage
Systems
Araneae
(Spiders)
Diptera
(Flies)
Opiliones
(Harvestman)
Carabidae
(Ground
Beetles)
Homoptera
(Aphids/ Plant Hoppers)
Staphylinidae Hymenoptera
(Rove Beetles) (Ants/Wasps)
Hemiptera
(True bugs)
Total Arthropods
1200
2010
1000
800
600
400
2011
Other
Pollinators
Parasites
Ominivores
Herbivores
Detritivores
Predators
200
0
System 3
System 4
System 3
System 4
Year and Cropping System
Figure 1. Total number of arthropods per system (n=12 traps/system) in
Systems 3 (no-till) and 4 (conventional till) in Start 1 (28 June 2010) and Start
2 (18 July 2011).
Mean Proportion of Epigeal Arthropods in Field Corn
Mean Proportion (%)
Total Arthropods per Corn Cropping System
2010
2011
Predators
Detritivores
Herbivores
Ominivores
Parasites
Pollinators
Other
System 4
System 3
System 4
Cropping System
Figure 2. Mean proportion by tropic group of arthropods (n=12 traps/system) in Systems 3
(no-till) and 4 (conventional till) in Start 1 (28 June 2010) and Start 2 (18 July 2011).
Table 1. Percent abundance of predominant predators (n=12 traps/system) in
Systems 3 (no-till) and 4 (conventional till) in Start 1 (28 June 2010) and Start 2 (18
July 2011).
Percent Abundance
2010
2010
2011
2011
Among Predators (%)
System 3
System 4
System 3
System 4
Araneae
44.3
30.7
62.2
38.0
Carabidae
28.8
35.2
21.4
24.2
Staphylinidae
20.7
20.0
8.1
27.4
Table 2. Percent abundance of Carabidae species by their trophic group (n=12
traps/system) in Systems 3 (no-till) and 4 (conventional till) in Start 1 (28 June 2010)
and Start 2 from (18 July 2011).
Trophic
2010201020112011Species
Group System 3 System 4 System 3 System 4
Agonum muelleri
Omnivore
2.08
Agonum placidum
Omnivore
0.69
Agonum puntiforme
Omnivore
9.03
2.08
Amara spp
Omnivore
9.03
1.39
Anisodactylus sanctaecrucis
Omnivore
5.56
74.68
40.00
Bembidion quadrimaculatum
Carnivore
1.27
0.00
Bembidion rapidum
Carnivore
2.78
Bradycellus rupestris
Carnivore
9.72
16.67
Chalenius tricolor tricolor
Omnivore
1.39
1.39
Cyclotrachelus furtivus
Carnivore 22.22
22.22
Elaphropus incurvus
Carnivore
0.69
Hapalus spp
Omnivore
2.08
1.39
Omnivore
Harpalus affinus
0.69
Harpalus herbivagus
Omnivore
0.69
Harpalus pensylvanicus
Omnivore
15.00
Harpalus rubripes
Omnivore
1.39
Poecilus chalcites
Omnivore
0.69
6.33
Poecilus lucublandus
Omnivore
5.06
30.00
Pterostichus melanarius
Omnivore
0.00
Scarites quadriceps
Omnivore
1.27
Stenolophus comma
Omnivore
11.39
15.00
Trechus apicalis
Carnivore
0.69
Unknown
0.69
2.78
-
Orthoptera
(Grasshoppers/ Crickets
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
Photo Credits: Steven Jacobs (Araneae); Canadian Biodiversity Information Facility (Carabidae); Gerald J. Lenhard, Bugwood.org
(Staphylinidae); Gary Alpert, Bugwood.org (Diptera); Clemson Univ. – USDA Cooperative Extension Slide Series, Bugwood.org (Hemiptera);
Frank Peairs, Bugwood.org (Homoptera); Joseph Berger, Bugwood.org (Hymenoptera); David Cappaert, Bugwood.org (Orthoptera and
Opiliones); Cathy Nardozzo (pitfall)
System 3
Results
• A total of 1845 and 1640 arthropods were captured in corn
systems in 2010 and 2011, respectively (Fig. 1) .
• Beneficial (predators, detritivores, parasitoids, pollinators) were
more predominant than potential pest (herbivores) insects, with
predators being the most abundant of the beneficial insects (Fig.
2).
• Araneae (spiders) was the largest order of arthropods in the pitfall
traps (Table 1).
• The second largest order was Coleoptera, with the Carabidae
(ground beetle) and Staphylinidae (rove beetle) representing the
largest percentage of predatory beetles.
• Ground beetle species diversity changed dramatically from 2010
to 2011 (Table 2).
Conclusion
• The insect community was dominated by beneficial insects.
• We did not observe damaging levels of plant-feeding insects
despite the absence of insect-control inputs.
Acknowledgements
This research was funded by a USDA CSREES-ICGP Risk
Avoidance and Mitigation Program competitive grant 2007-03085 to
Mary Barbercheck, Jason Kaye, Dave Mortensen, Jayson Harper,
Nancy Ellen Kiernan.
Research Assistants: Salvatore Anzaldo, Barb Brodzina, Thomas
Coulter, Reid Garner, Chloe Greenberg, Karim Hemaday, Joseph
Herbstritt, Lauren Hill, Caroline Kindall, Andrew Russell, Matt Zanella