Undergraduate Honors Theses

Thesis Defended

Spring 2015

Document Type

Thesis

Type of Thesis

Departmental Honors

Department

Ecology and Evolutionary Biology

First Advisor

Cesar Nufio

Abstract

Bees (family: Apidae) are important ecologically and economically as primary pollinators of many natural and agricultural systems. Given current concerns about declining numbers of bees, many survey-oriented studies are being conducted to understand factors that contribute to the loss of bees and to direct conservation efforts. For these studies to be informative, researchers must be aware of biases associated with different sampling methods. Given their effectiveness at capturing a large number of insect individuals, blue vane traps are becoming a widely used method for sampling bees.

We investigated sampling biases associated with blue vane traps versus the more commonly used pan traps at two different high elevation sites in the Front Range of Northern Colorado. At each site, (1) sampling efficiency (number of species and abundance of bees associated with each method) were compared and (2) the overlap in species sampled by each method determined. We also examined the degree to which potential biases in the bees sampled by each method was associated with life history characteristics of the bees (level of sociality, floral specialization, nesting habits, and body size). At both surveyed sites, blue vane traps captured roughly 4 times more individuals and 1.5 times more species than paired sets of pan traps. Individual-based rarefaction curves, a calculation of species richness per individual sampled, however, showed that for an equal number of individuals sampled by both methods, pan traps would actually sample more species. To survey an equal number of individuals between trap types, it is recommended to employ 4 times as many sets of pan traps than blue vane traps. The degree of similarity between species associated trap types was approximately 20%. Differences in species associated with each trap type were not caused by bee sociality, floral specialization, nesting habits, or body size. Given the differences in sampling efficiency and the low overlap of species captured by the two sampling methods, caution is suggested when comparing studies that employed only one of these methods. Rather, the use of both methods is suggested to better represent the species present within a given area.

Included in

Entomology Commons

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