Conservation biological control in a multi-strata agroforestry system

Kranz, Adam

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https://hdl.handle.net/2142/98436 Copy

Description

Title

Conservation biological control in a multi-strata agroforestry system

Author(s)

Kranz, Adam

Issue Date

2017-07-20

Director of Research (if dissertation) or Advisor (if thesis)

Miller, James R.

Committee Member(s)

• Molano-Flores, Brenda
• Wander, Michelle
• Hanks, Lawrence

Department of Study

Natural Res & Env Sci

Discipline

Natural Res & Env Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Agroforestry
• Conservation biological control
• Intercropping
• Natural enemies
• Polyculture
• Structural diversity
• Mowing

Abstract

Polyculture agroforestry is a new sustainable agriculture system modelled on the plant structural and species diversity of native oak savanna. Advocates of the system claim that it will advance conservation goals by providing ecosystem services like habitat provision and carbon sequestration, but also provide localized ecosystem services that benefit farmers. Pest control by wild predators and parasitoids could be an especially valuable service in fruits and nuts, the main cash crops in polyculture agroforestry systems. To understand how diverse agroforestry’s unique traits would affect pest control, I evaluated the response of arthropod pest and natural enemy guilds to variations in shrub layer composition and alley mowing. Shrub composition affected guilds on shrubs but had little effect on arthropods in neighboring apple trees. Pest guilds linked to apple damage were not affected by shrub composition, and pest damage rates were unchanged. Mowing did cause arthropods in groundcover to use shrubs and trees as refuge habitat. However, the shrubs and trees that offered suitable refuge were alternate hosts to pest insects. Mowing thus increased abundance of pests but not enemies, likely resulting in higher rates of pest damage rather than the opposite. I found no evidence that either strategy has potential to improve pest outcomes. Overall, I conclude that pest management in polyculture agroforestry systems is likely to be an obstacle for farmers rather than a boon. This fact should be made clear to potential adopters of the system, and future designs should choose crops that are tolerant or immune to pest damage to the extent possible.

Graduation Semester

2017-08

Type of Resource

text

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http://hdl.handle.net/2142/98436

Copyright and License Information

Copyright 2017 Adam Kranz

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