Graduate Program

Biological Sciences

Degree Name

Master of Science (MS)

Semester of Degree Completion

2008

Thesis Director

Ann Fritz

Thesis Committee Member

Eric Bollinger

Thesis Committee Member

Gary Fritz

Abstract

This study compared the occurrence of beetles in the family Silphidae using historical collection records with that of field collections from five different sites within McHenry County. The five sites include: Glacial Park, Woodstock, Silver Creek, Rush Creek, and Coral Woods. Historically, 11 known silphid species have been found in McHenry County, compared with seven species found during this study' collection period.

Percentages of silphid species at each site was calculated, as well as total number of individuals sampled, and two indices of diversity (Shannon-Weiner and Simpson's) were applied to both current and historical collection data. The historical collection (when analyzed using either diversity index) was about twice as diverse as today (H'=2.11; ^=0.14). In terms of study collection sites, overall, those areas of higher human population and development had far fewer species, a trend of species richness being reduced over time in McHenry County.

The most commonly collected species in the historical collections was Necrodes surinamensis (13 individuals) however, none were found in this study, even though this study represents almost ten times the number of specimens collected (859 beetles versus the 86 total historical specimens).

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