How can green infrastructure affect bumble bee colony health and success?

Legacy cities often experience aging and/or decaying sewer infrastructure. As such, cities commonly have an abundance of vacant land. Thus the use of Green Infrastructure (GI) to supplement existing infrastructure is an appealing option to provide effective wastewater management and potentially improve pollination resources for wild bees. However, the effect of these GI sites on bee health is unknown. Our objective is to determine if green infrastructure improves the health of bumblebee colonies by comparing colonies deployed in GI sites to those deployed to vacant lots (VLs). We hypothesize that bumble bee colonies in GI sites will be healthier than those in vacant lots due to the more abundant pollen and nectar resources present in GI sites. In June 2024, 16 Bombus impatiens colonies were deployed across Cleveland and East Cleveland in GI and VL sites. Colonies were deployed for 45 days and then returned to the lab for processing of health metrics. The number of emerged non-gyne cells were taken as measures of colony growth. Emerged gynes were counted and measured for wet-weight, head width, and radial wing cell length as a measurement of body size. Upon analysis of these data, we expect colonies from green infrastructure sites to have produced more workers, males, and gynes than vacant lot sites. We also expect gynes produced from GI sites to be larger than those from VL sites. This data will help us better predict how bumble bee health is affected by common urban greening methods.