Unveiling the submerged secrets: bumblebee queens' resilience to flooding

Abstract

In a previous study, an experimental oversight led to the accumulation of water filling a container housing diapausing bumblebee queens. Surprisingly, after draining the water, queens were found to be alive. This observation raises a compelling question: can bumblebee queens endure periods of inundation while overwintering underground? To address this question, we conducted an experiment using 143 common eastern bumblebee (Bombus impatiens) queens placed in soil-filled tubes and subjected to artificially-induced diapause in a refrigerated unit for seven days. Tap water was then added to the tubes and queens (n=21/treatment) were either maintained underwater using a plunger-like apparatus or left to float naturally on the water’s surface for varying durations (8h, 24h, or 7 days) while remaining in overwintering conditions. Seventeen queens served as controls. After the submersion period, queens were removed from water, transferred to new tubes with soil, and kept in cold storage for 8 weeks. Overall queen survival remained consistently high (89.5 ± 6.4%) across all treatments and did not differ among submersion regimes and durations. These results demonstrate the remarkable ability of diapausing B. impatiens queens to withstand submersion underwater for up to one week, indicating their adaptations to survive periods of flooding in the wild.