Assessing the Effects of the Conservation Reserve Program on Cavity-Nesting bees in Colorado

Morphew, Alexandra

Undergraduate Honors Thesis

Assessing the Effects of the Conservation Reserve Program on Cavity-Nesting bees in Colorado Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/undergraduate_honors_theses/0g354f58r

Abstract

The conversion of natural habitat for agricultural use continues to be a prevalent threat to wild pollinator populations, although the establishment of semi-natural habitats in agroecosystems can successfully bolster bee populations. Conservation Reserve Program (CRP) plantings provide a unique opportunity to understand the effects of conservation efforts on wild bee populations. To assess the conservation value of CRP plantings for native pollinators, I analyzed the contents of trap nests deployed in 29 field sites over the 2014 flowering season, including 18 CRP grassland plantings and 11 rangelands in northeastern Colorado. I compared the abundance and diversity of cavity-nesting bees between site types, and explored mechanisms driving reproduction and performance of the most common native cavity-nesting bees. Despite significantly higher plant species richness on rangeland sites, CRP plantings supported greater wild bee abundance and Megachile spp. fecundity, although there was no difference in genus richness between the two land types. Additionally, there was no significant difference in the body size of native female Megachile brevis. Only one introduced species was present in our samples (Megachile rotundata), and was not found in rangeland sites, suggesting that rangeland plant communities may play an important role in supporting native bee species. These results indicate that compared with rangelands, the Conservation Reserve Program provides significant benefits to wild bee populations. Further studies should investigate the persistence of these patterns over multiple flowering seasons and potential mechanisms driving cavity-nesting bee population dynamics within these agroecosystems.

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