UC Riverside

Bumble bee colony development is shaped by reproductive and behavioral transitions within the nest, as well as broader ecological conditions that influence colony members across landscapes. Broadly, nests are founded by independent queens, who perform all essential tasks during the earliest stages of nest development, including foraging, egg laying, incubation, and feeding. As workers emerge, colonies transition into a eusocial phase, during which workers assume many in-nest and out-of-nest tasks and queens begin to specialize in reproduction. This dissertation examines the early stages of bumble bee colony development and explores how social and environmental variation may shape colony function beyond this initial stage. In Chapter One, I investigate how social context influences queen reproductive plasticity during early colony development by examining whether brood and workers regulate queen egg-laying, as well as the timing of this regulation. In Chapter Two, I extend this focus on plasticity by examining brood care behaviors after worker emergence. Specifically, I experimentally remove workers from colonies at different sizes and quantify changes in queen-provided brood care. Finally, in Chapter Three, I examine worker body size variation in a local species (Bombus vosnesenskii) to determine whether morphology varies across broad landscape features in California. Collectively, this work demonstrates that bumble bee colony development is shaped by dynamic interactions among social context, queen behavior and environmental conditions. By exploring these three facets, this dissertation provides insights into how bumble bee colonies develop and respond to social and environmental variation.