Effects of the agricultural landscape on native bees and insect pests in recently established pollinator habitat

Kangas, Madeline Nicole

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Description

Title

Effects of the agricultural landscape on native bees and insect pests in recently established pollinator habitat

Author(s)

Kangas, Madeline Nicole

Issue Date

2020-12-09

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

Miller, James R

Committee Member(s)

• Ratcliffe, Susan
• Harmon-Threatt, Alexandra

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)

• Conservation Reserve Program
• CP-42
• native bees
• agroecosystem
• pollinator conservation
• insect pests
• integrated pest management

Abstract

Bees require pollen and nesting resources, however the availability of habitat that continuously provides these has declined with the conversion of land to monocrop agriculture. Production agriculture is a hostile environment for bees that need food outside the timeframe of a crop’s flowering period, and habitat loss has been a major driver of bee decline. In response to bee decline, conservation measures have been employed across the agricultural landscape. One of the largest private lands conservation programs in the United States, the Conservation Reserve Program (CRP), has within the last decade added an initiative called Conservation Practice 42 (CP-42) Pollinator Habitat Establishment. In this program, farmland is taken out of production and converted to diverse flowering vegetation in an effort to restore habitat for pollinators. Yet, little research has been conducted on whether these programs are successfully promoting diverse bee communities and whether there are adverse effects on surrounding cropland by way of supporting agricultural insect pests. To address these unknowns, I have studied the native bee and insect pest communities of CP-42. Chapter 1 of my thesis provides a review covering habitat loss in agricultural landscapes and the challenges to recreating habitat. This review is followed by two studies conducted in East-Central Illinois, a region dominated by the production of corn (Zea mays) and soybeans (Glycine max), but with increasing adoption of CRP. Chapter 2 and 3 are ecological studies conducted on recently established CP-42 sites. In Chapter 2, I collected bees on 16 CP-42 sites and 7 nature preserves, which acted as references for potential bee diversity in the region, during the 2018 and 2019 growing seasons. I found that mean native bee abundance and richness was similar between the two types, although there were twice as many CP-42 sites as preserves. Local flower diversity impacted bees more than landscape composition and distance to the nearest nature preserve. It is possible then that either the production agriculture landscape may be more penetrable to bees than previously thought or that natural areas are more degraded than previously thought. In Chapter 3, I explored the presence of agricultural insect pests in CP-42 and compared them to abundances found in adjacent soybean fields and established economic thresholds for treatment. I surveyed for ten pest groups on a subset of fields from Chapter 2 (n=7 CP-42 sites paired with one soybean field each). Of the ten target pests, nine were present in our study. Grasshoppers (Caelifera) and Japanese beetles (Popillia japonica) made up more than half of the total observations with Japanese beetles being most prevalent in soybean fields and grasshoppers in CP-42 sites. Although nine insects were present, none occurred in abundances equal to or greater than the economic thresholds. Moreover, the combined abundances of insects in CP-42 and soybean fields also failed to meet the threshold recommended for intervention. In combination, these results suggest that 1) CP-42 sites can promote an abundant and rich community of bees despite their isolation within row-crop agriculture, and 2) CP-42 is not adversely affecting surrounding cropland by supporting economically damaging abundances of insect pests. Continued adoption of pollinator conservation measures even in resource-poor landscapes holds potential to increase native bee diversity and mitigate bee population declines.

Graduation Semester

2020-12

Type of Resource

Thesis

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Copyright 2020 Madeline Kangas

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