Landscape effects on bumble bee (Hymenoptera: Apidae) colony performance and fitness in New York State

Abstract

Pollinators such as bumble bees are in decline as a result of many factors, including loss of habitat. Initiatives to improve and restore pollinator habitat have become increasingly popular. However, to most effectively conserve pollinators, we need a better understanding of which habitats are limiting to their survival and growth at the landscape scale. Our study examined the performance of the common eastern bumble bee, Bombus impatiens (Cresson), in four common landscapes (natural, suburban, conventional agriculture, and organic agriculture). In the summers of 2016 and 2017, 64 commercial bumble bee colonies were deployed across 16 sites (4 in each landscape) and their growth (weight and bee abundance) and fitness (caste production), and survival were monitored weekly. Across both years, colonies in suburban landscapes were approximately 28-30% lighter, had 13-15% less bee abundance, produced 38-40% fewer worker cells, and 45-50% fewer drones cells. Colonies in suburban landscapes also experienced queen death at a rate two-times faster. In 2016, 100% of the colonies in suburban landscapes were removed due to queen death, which was six days earlier than the overall average across all landscapes. In 2017, over 50% of the suburban colonies had queens die before the overall average across all landscapes. Our study adds to the growing literature highlighting the influence of the landscape context on pollinator populations, particularly in suburban environments. Overall, our results suggest that suburban landscapes are suboptimal for B. impatiens while agricultural landscapes were not detrimental to colony growth or survival. Future research is needed to identify mechanisms that are responsible for the reduced performance of bumble bee colonies in suburban landscapes, especially regarding floral resources, pesticides, and pathogens.