Pollen Quantification
Pollen loads were assessed by comparing non-bee insect visitors to the
genus of bee with the largest pollen loads, Halictus , using a
generalized linear model (GLM) using quasi-poisson distribution. A GLM
was used in place of a linear model to account for the non-normal
distribution of data. As the data were also overdispersed, a
quasi-poisson distribution was chosen (Ver Hoef and Boveng 2007). The
pollen counts for each respective genus were used as response variable.
Each non-bee genus was treated as a factor and included as explanatory
variables. Visualizations of pollen loads, and insect abundance were
presented using TreeMaps generated in R (version 2.5-5). To assess total
available pollen contribution, data from observations were combined with
pollen counts from collected specimens, total pollen = observed
abundance x average pollen count. The percentage of total pollen was
calculated by taking the average pollen load for each insect taxon and
dividing it by the absolute sum of total pollen counts.