Pollinators, pumpkins and primers, oh my! a preliminary exploration of wild Bombus impatiens population trends in Pennsylvania

In Pennsylvania, Bombus impatiens (the Common Eastern Bumble Bee) is a pollinating bee species active in both natural and managed landscapes. Because of the potential economically significant pollination services provided by Bombus impatiens in agriculture, there is interest in understanding the population dynamics of Bombus impatiens.

We have completed several measures on Bombus impatiens actively foraging in dozens of commercial pumpkin fields throughout Pennsylvania over the course of 3+ years. For one measure, we collected 200 bumble bee specimens from each field in order to conduct microsatellite fragment (microsat) analysis to determine the number of unique bumble bee colonies represented in each of the 200 samples. Thus far, we have completed preliminary analysis on a total of 4 collections of bumble bee samples that were taken from 2 farms in Lancaster County, PA from 2013 and 2014. For this preliminary analysis, we used 10 primers at different loci to establish bumble bee sisterhoods. We determined that several of these primers needed to be substituted in order to provide a more accurate determination of sisterhoods. We further optimized the established micosat analysis protocols in order to get more consistent results. Once these changes were accounted for, we were able to produce data comparing colony numbers by year and by farm.

Additionally, in those same pumpkin fields we measured the rate as which Bombus impatiens visited pumpkin flowers throughout the pumpkin bloom season. Future work will compare visitation rates and colony numbers to establish any potential correlations. We will also complete analysis on the remaining bumble bee collections taken from additional pumpkin fields during additional years in order to approximate population trends for the agriculturally significant subset population of Bombus impatiens in Pennsylvania.