A survey and historical comparison of the Megachilidae (Insecta: Hymenoptera) of Itasca State Park, Minnesota

Abstract

The University of Minnesota Insect Collection holds a rich collection of bees from Itasca State Park, Minnesota, in 1937 and 1938. This collection formed the historical baseline data for comparison with a new survey conducted from 2011-2013. Bees were collected with timed net surveys and trap nests at eight different sites within the park. Megachilidae were the focal family for the current study, due to their importance as commercial pollinators and their unique nesting habits. Species richness and diversity of Megachilidae in the new survey were both significantly lower than that of the historical collection, and remained lower (but not significantly) when species accumulation curves were extrapolated to estimate the true species richness. Eleven species in the historical collection were not rediscovered, while three species not previously collected in Itasca State Park were found in 2011-13. Some possible explanations for this apparent decline are discussed.