Temperature influences desiccation resistance of bumble bees

Authors: BOTSCH, JAMIESON - Oak Ridge Institute For Science And Education (ORISE); Daniels, Jesse; BUJAN, JELENA - Ruder Boskovic Institute; Roeder, Karl

Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/3/2024
Publication Date: 5/9/2024
Citation: Botsch, J.C., Daniels, J.D., Bujan, J., Roeder, K.A. 2024. Temperature influences desiccation resistance of bumble bees. Journal of Insect Physiology. 155. Article 104647. https://doi.org/10.1016/j.jinsphys.2024.104647.
DOI: https://doi.org/10.1016/j.jinsphys.2024.104647

Interpretive Summary: Few studies have examined the interactive effects of temperature and humidity on desiccation resistance in bees, despite their ecological and economic importance. Here, we crossed temperature (20, 25, and 30°C) with humidity (<5, 50, >95% RH) manipulations and measured survival, water loss, and water content of the common eastern bumble bee, Bombus impatiens. We found that both higher temperature and lower humidity increased water loss, while warmer temperatures reduced survival and lower humidity decreased water content. This study raises important questions about the mechanisms underpinning water loss in bumble bees and how those bees will perform in a warming and drying climate.

Technical Abstract: Ongoing climate change has increased temperatures and the frequency of droughts in many parts of the world, potentially intensifying the desiccation risk for insects. Because resisting desiccation becomes more difficult at higher temperatures and lower humidity, avoiding water loss is a key challenge facing terrestrial insects. However, few studies have examined the interactive effects of temperature and environmental humidity on desiccation resistance in insects. Such studies on bees (Hymenoptera: Apoidea: Anthophila) are especially rare, despite their ecological and economic importance. Here, we crossed temperature (20, 25, and 30°C) with humidity (<5, 50, >95% RH) manipulations and measured time to mortality, water loss rates, and the water content at mortality of bumble bees (Bombus impatiens). We found that both higher temperature and lower humidity increased water loss rates, while warmer temperatures reduced survival time and lower humidity decreased water content at mortality. Additionally, we observed large intraspecific variation in water balance traits between colonies, and larger individuals survived longer and had slower water loss rates under desiccating conditions. This study raises important questions about the mechanisms underpinning water loss in bumble bees and suggests that frequent access to nectar may be especially important for bumble bees’ water balance and survival in a warming and drying climate.