Date of Award

6-2010

Document Type

Union College Only

Degree Name

Bachelor of Science

Department

Biology

First Advisor

Steven Rice

Language

English

Keywords

species, growth, Blue, plants, Lupine

Abstract

In this era of accelerated habitat loss and fragmentation, species with specific requirements for growth tend to suffer the most. One such species is the endangered Karner Blue Butterfly (Lycaeides melissa samuelis), which relies solely on the leaves of the Blue Lupine (Lupinus perennis) for larval fodder. Several experiments have suggested that Blue Lupine growing conditions may affect their suitability for Karner Blues, but results have remained inconclusive. Growth conditions may affect plant suitability through leaf properties—specifically, leaf nutritional quality. We have analyzed leaf tissue properties from Blue Lupine grown under different conditions in the field to (1) determine which treatments (if any) are most effective at increasing host plant suitability, and (2) better define the mechanism by which treatments aid Karner Blue growth and reproduction. Mature Blue Lupine plants were subjected to burning, deadheading, and mowing treatments at different points over a growing season. Leaves from these plants were then fed to captive Karner Blue Butterfly larvae and analyzed for leaf mass area (LMA), nitrogen, carbon, and glucose. We found that only nitrogen and nitrogen:glucose ratios varied differently over time with respect to treatment. Leaves from Blue Lupine that were burned on May 1st and harvested May 23rd through June 5th showed significantly higher nitrogen contents than all other leaves harvested at those times. This extra nitrogen may be responsible for observed increases in oviposition rates and the presence of a third brood in Karner Blues fed leaves from Blue Lupine that had been subjected to burning treatments. Thus, burning, especially early in the growing season, may be an important aspect of Karner Blue management.

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