Submission Date

7-19-2018

Document Type

Paper- Restricted to Campus Access

Department

Biology

Faculty Mentor

Cory Straub

Student Contributor

Carter Usowski

Comments

Presented during the 20th Annual Summer Fellows Symposium, July 20, 2018 at Ursinus College.

Project Description

Agricultural ecosystems are species poor in comparison to natural ecosystems, and this has led to an increased susceptibility to pest outbreaks. In attempt to control outbreaks, some farmers have implemented the use of pesticides, which have been shown to threaten both human and environmental health. Increasing plant species diversity in agricultural ecosystems has been proposed as an alternative strategy. This may reduce herbivore abundance because herbivores are less efficient at finding preferred plant species when surrounded by non-preferred species (Resource concentration hypothesis) and/or because predatory insects that consume herbivores are more efficient and/or abundant in species-rich systems (Enemies hypothesis). We established a forage crop diversity experiment at the Ursinus College Whittaker Environmental Research Station using four plant species with three levels of plant species richness among treatments- monoculture, biculture, and all four species together. We swept four times throughout the summer, then identified and counted the insects within each collection. I concentrated on two focal pests, the potato leafhopper (Empoasca fabae) and thrips (Thripidae), tracking their change in abundance relative to plant species richness. I predict that increasing plant species richness will reduce pest abundance as predicted by the Resource concentration and Enemies hypotheses.

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